Acute total knee arthroplasty for traumatic proximal tibial fractures: A systematic review

Abstract

BACKGROUND

Proximal tibial fractures (PTFs), including tibial plateau fractures (TPFs), are usually managed with osteosynthesis; however, in elderly patients with pre-injury knee osteoarthritis and osteoporotic bone, performing an acute total knee arthroplasty (aTKA) became a viable management option.

AIM

To explore the indications, patient characteristics, implant selection, and reported outcomes (functional, radiological, complications, and revision rates) after aTKA to manage traumatic PTFs.

METHODS

A systematic literature search of English-language studies reporting on the aTKA for managing PTFs, including TPFs, was conducted across three major databases (EMBASE, PubMed, and Scopus) from inception to December 2024.

RESULTS

Of the 1055 reviewed articles, 14 studies with 174 patients met the inclusion criteria. The mean age was 71.3 years, and 60.9% were females. The incidence of pre-injury knee osteoarthritis ranged from 22.7% to 100%, and 90.8% were TPFs. A medial parapatellar approach was used in all cases, and a posterior-stabilized implant was most commonly used (49.4%). Of 103 patients in whom extras were used, 97.1% had a tibial stem, and 20.4% required metal augments for tibial bone defect reconstruction. After a mean follow up of 28.5 months, the maximum knee flexion as reported from 121 patients had a mean of 110.3 degrees, while the functional outcomes per the Knee Society Function and Knee Scores were reported in 129 patients and had good and fair outcomes, respectively. Complication incidence was 16.67%, with infection as the most common complication, and revision was required in only 3 (2.3%) patients.

CONCLUSION

The aTKA for managing PTFs is an appealing management option with acceptable functional, complication, and revision outcomes. Various implants and extras can be employed based on fracture type, collateral ligament status, and bone defect size. Better-designed studies with a larger number of patients and longer follow up are needed to validate the outcomes of such a management approach compared to other management options.

Key Words: Proximal tibial fracture; Tibial plateau fracture; Total knee arthroplasty; Total knee replacement; Systematic review; Outcomes

Core Tip: Managing proximal tibial fractures, particularly tibial plateau fractures, in elderly patients with osteoporotic bone and pre-existing knee osteoarthritis is challenging. This systematic review evaluated the role of acute total knee arthroplasty as a primary treatment option. Fourteen studies involving 174 patients were analyzed. Most were elderly females with total knee arthroplasty and pre-injury osteoarthritis. Posterior-stabilized implants were commonly used, often with tibial stems and metal augments. Outcomes were favorable, with a mean flexion of 110 degrees and generally good Knee Society Scores. Complications occurred in 16.7%, and revisions in 2.3%. Despite promising results, evidence quality was low, warranting larger comparative studies.

INTRODUCTION

Although proximal tibial fracture (PTFs) represents only about 1% of adult fractures, in the elderly population, they pose a specific challenge to the treating surgeons due to possible osteoporosis, soft tissue fragility, a higher incidence of concomitant pre-injury knee osteoarthritis (OA), and associated medical comorbidities[1-3]. Furthermore, the management becomes more challenging if these were tibial plateau fractures (TPFs), which have an incidence of about 24%, due to articular surface involvement and the possibility of injury-induced bone defects[1,4-6].

The main goal of treating PTFs or TPFs is to achieve anatomical fracture reduction and secure fixation to promote proper union and early patient mobilization for better functional recovery[2,4,7,8]. These goals could be achieved by various management strategies, including conservative management for minimally displaced fractures, open reduction and internal fixation (ORIF) for displaced fractures and those involving the articular surface, and total knee arthroplasty (TKA) either in an acute setting as a definitive management line or in a delayed (secondary) fashion to manage fracture sequelae[2,9-12]. It is worth noting that in the elderly population with PTFs, ORIF failure occurs in about 30% to 97% of the cases[10,13-16].

The TKA conversion rate after TPFs reaches up to 5%[17]. Furthermore, delayed TKA for managing sequelae of TPFs, such as post-traumatic OA, showed higher complication incidence reaching up to 60%[13,18,19]. Therefore, there has been increasing interest in performing acute TKA (aTKA) for managing PTFs in relatively older patients with osteoporotic bone or pre-injury knee OA, which has shown encouraging outcomes compared to other management modalities[13,17,20-22]. The current systematic review aimed to explore indications, patient characteristics, implant selection, and reported outcomes (functional, radiological, complications, and revision rates) following aTKA for traumatic PTFs.

MATERIALS AND METHODS

The current systematic literature review was carried out following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines[23], and it was initially registered in PROSPERO (registration ID: CRD42024627838).

Study eligibility (inclusion and exclusion criteria)

The inclusion criteria were English language studies (randomized controlled trials, cohort studies, case series, and case reports) reporting the outcomes (clinical, radiological, and complications) of performing aTKA as the primary management of traumatic PTFs (intra-articular or extra-articular). We excluded studies not published in English, performed on animal models, other publication types (reviews, editorials, abstracts, technical notes, and commentaries), and studies not including the outcomes of interest, or if those outcomes could not be extracted (studies on femoral and tibial periarticular knee fracture where the outcomes could not be separated).

We developed a search strategy based on the predefined PICO (population, intervention, comparison, and outcome) model. The population of interest was patients with traumatic PTFs (intra-articular or extra-articular). The intervention was TKA as the primary intervention after trauma. Comparison with other management modalities (if present), such as ORIF or non-operative management. The main outcomes were functional, radiological, complications, and revision rate outcomes.

Literature search (information sources and search strategy)

A comprehensive English literature search was performed on December 15, 2024 through three databases (EMBASE, PubMed, and Scopus), using various combinations of the following terms (TKA, total knee replacement, PTFs, and TPFs). The details of the search strategy are presented in Supplementary Table 1.

Selection process

All the results (1055 articles) were downloaded to the EndNote 21 program. The first step was to identify and remove duplicates. Two authors (Althaqafi RMM and Altahir A) performed the screening and initial selection based on the predetermined criteria. Titles and abstracts of the retrieved eligible articles were screened, and their full text was reviewed for final inclusion. Any controversies were resolved through discussion among the authors, and the first author (Khalifa AA) was consulted as needed. The number of citations identified, included, and excluded at each screening step, along with the reasons for exclusion, is presented according to the PRISMA flowchart (Figure 1). The articles for final inclusion were divided equally among the authors; each extracted data from the assigned articles. After finishing data extraction, the authors exchanged their data, and each reviewed the data extracted by their colleague. If a controversy or missing data were present, a discussion between the authors was held to resolve any disagreement.

Figure 1 Preferred reporting items for systematic reviews and meta-analyses flowchart. TKA: Total knee arthroplasty.

Data collection and critical appraisal

The following data were extracted: (1) Articles’ characteristics [author(s), year of publication, country of origin, type of study]; (2) Patient characteristics (age, sex, comorbidities, status of knee OA, and bone quality assessment); (3) Fracture characteristics (mode of trauma, fracture location, and classification); (4) Surgery details (timing, surgical approach, implant type, and if extras were used); and (5) Outcomes (functional, radiological, complications, and revision data). Any further data deemed suitable for reporting was extracted.

ROB assessment

A unified risk of bias (ROB) evaluation was performed for all included studies using the National Institutes of Health Quality Assessment Tool items for observational case series, cohort, and cross-sectional studies (https://www.nhlbi.nih.gov/health-topics/study-quality-assessment-tools), to maintain methodological consistency across observational designs. Each study was assessed across five core domains: Patient selection, clarity of intervention description, validity of outcome measurement, adequacy of follow-up, and statistical/reporting transparency. All ROB items were independently evaluated by two authors (Altahir A and Althaqafi RMM), and all discrepancies were resolved by discussion to reach consensus or by consulting a third author (Khalifa AA).

Statistical analysis

Due to the heterogeneity of study designs and outcome measures, a meta-analysis was not feasible; therefore, only a qualitative (descriptive) synthesis was conducted. However, we used the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system to generate the evidence certainty level.

RESULTS

Studies and patient characteristics

Initially, we had 20 full texts for inclusion; however, in five articles, we could not isolate data on aTKA for managing PTFs because they combined other treatment modalities or distal femoral fractures[3,8,24-26]. In contrast, one article reported on delayed TKA (eight months from the trauma)[27]. We finally included 14 studies for analysis[28-41]. Two studies were published from each of Iran[35,37] and Malaysia[29,41], while one was published from each of the following: Belgium, China, Egypt, Finland, France, Germany, Italy, the Netherlands, Singapore, and the United Kingdom. Study types were as follows: Nine case series, two case reports, two retrospective cohort studies (one compared aTKA vs ORIF, the other compared acute vs delayed TKA), and one cross-sectional study. The 14 articles included 174 patients [68 (39.1%) males and 106 (60.9%) females], with an average age of 71.3 years, ranging from 53 years to 96 years, and all had unilateral fractures.

Seven studies (111 patients)[28,35-40] reported on concomitant preinjury knee OA, with an incidence ranging from 22.7% to 100%. Proper evaluation of the preoperative bone density profile was reported in one study (11 patients)[35], where the patients had an absorptiometry scan evaluation at least 6 months before the injury as a part of their routine rheumatology follow-up, and their mean T-score was -3.8 ± 0.7, the remaining articles reported comments on bone density based on either patients’ history, radiographic or intraoperative data (Table 1).

Table 1 Basic studies, patients’, and fracture characteristics, mean ± SD/n (%).

Ref.	Country	Study type	Total number of patients included in the study	Number of patients who had aTKA	Age	Gender		Comorbidities	Concomitant knee OA	Evaluating abnormal bone profile (author’s remarks)	Fracture details
						Male	Female				Trauma mechanism	Fracture location	Classification
Abdelbadie et al[28], 2020	Egypt	Retrospective cohort study	43 (22 aTKA vs 21 ORIF)	22	67.1 (60-73)	8	14	86.4% of the patients [diabetes (36.4%), HT (35.5%), IHD (27.3%), CLD (4.5%)]	5 (22.7)	NA [9 (40.9) patients were on bisphosphonates]	14 high energy (6 falls, 2 RTA, 6 MCA)	TPFs	Schatzker type II (7, 31.8%), Schatzker type III (8, 36.4%), Schatzker type IV (7, 31.8%)
Asikin et al[29], 2022	Malaysia	Case report	1	1	75	1	0	NR	NR	NA	High energy (MCA)	TPFs	Schatzker type V
Boureau et al[30], 2015	France	Case series	21 (10 distal femur fractures and 11 proximal tibia fractures)	11	79 (68-96)	8	3	NR (ASA III: 6, ASA II: 5)	NR	NA (all patients showed radiologic osteopenia)	NR	TPFs	5 Schatzker II, 2 Schatzker IV, 3 Schatzker V and 1 Schatzker VI
Haufe et al[31], 2016	Germany	Case series	30	30	78.4 (59-93)	13	17	NR	NR	NA	NR	TPFs	AO/OTA: Type B (13), type C fracture (17); 6: 41B2, 5: 41B3, 5: 41C1, 7: 41C2, and 7: 41C3
Hesmerg et al[32], 2024	Netherlands	Retrospective cohort study	68 (34 matched pairs: 12 aTKA vs 22 late TKA)	12	69.0 (65.3-79.5) (median)	1	11	NR [ASA I/II: 8 (66.7%)]	NR	NA	Traffic accident 2 (16.7%), fall from height 4 (33.3%), blunt trauma 1 (8.3%); other 4 (33.3%), unknown 1 (8.3%)	TPFs	Schatzker II (2, 16.7%). Type III (3, 25.0%). Type IV (1, 8.3%). Type V (4, 33.3%). Type VI (2, 16.7%)
Huang et al[33], 2016	China	Case series	6	6	69.5 (58-78)	3	3	NR	NR	NA	All were high energy (traffic accidents and falls from height)	TPFs	4 Schatzker V and 2 Schatzker VI
Kadakia et al[34], 2007	United Kingdom	Case report	1	1	85	0	1	NR: Patient’s chest radiograph showed evidence of previous scarring	NR	NA (operative findings revealed that the bone was mushy and porotic)	Low energy (fell on the knee from standing height)	TPFs	Schatzker type IV
Mirzatolooei et al[35], 2021	Iran	Case series	11	11	54.3 ± 4.7	0	11	RA [all patients were on anti-RA agents, especially corticosteroid (prednisolone) for at least 5 years (range: 5-8)]	11 (100)	It was evaluated by DXA scan 6 months before the surgery; the mean T-score was -3.8 ± 0.7	All were low energy	PTFs	NR
Sabatini et al[36], 2023	Italy	Case series	11	11	76 ± 6 (65-84)	4	7	NR	11 (100)	NA	8 low energy (simple fall), 3 high energy (car accident)	TPFs	AO/OTA: Type B (8), type C fracture (3); one (41B1), 5 (41B3), 2 (41B2), 1 (41C1), 2 (41C2)
Sarzaeem et al[37], 2017	Iran	Case series	30	30	67.6 ± 4.2 (61-78)	19	11	NR	23 (76.7)	NA (7 had osteoporosis)	14 high energy	TPFs + PTFs	AO/OTA: Type A (5), type B (22), type C fracture (3); 5 (41A), 22 (41 B), 3 (41 C)
Sivasubramanian et al[38], 2016	Singapore	Case series	3	3	70.4 (59.2-79.0)	1	2	NR	3 (100)	NA (poor bone stock)	All high energy	TPFs	2 Schatzker II and one Schatzker III
Tapper et al[39], 2020	Finland	Case series	22	22	74 ± 12 (53-88)	6	16	NR	5 (22.7)	NA (deficient bone stock)	13 low energy, 9 high energy	TPFs	6 Schatzker II, 7 Schatzker III, 2 Schatzker IV, 5 Schatzker V, 2 Schatzker VI
Vermeire and Scheerlinck[40], 2010	Belgium	Case series	12	12	73 (58-81)	3	9	NR	5 (41.7)	NA	6 low energy, 6 high energy	TPFs	AO/OTA: Type B (9), type C fracture (3); one 41-B1, 8: 41-B3, 3: 41-C3
Wui et al[41], 2020	Malaysia	Cross-sectional study	10 (6 distal femur, 2 proximal tibial, and 2 combined distal femur and proximal tibial fractures)	2	64 (55-76)	1	1	NR	NR	NA (poor bone quality)	NR	TPFs	AO/OTA: Type C fracture (2); one 41C3.1, one 41C3.3

TKA: Total knee arthroplasty; OA: Osteoarthritis; ORIF: Open reduction and internal fixation; NR: Not reported; NA: Not available; HT: Hypertension; IHD: Ischemic heart disease; CLD: Chronic liver disease; PTFs: Proximal tibial fractures; TPFs: Tibial plateau fractures; AO/OTA: Arbeitsgemeinschaft für Osteosynthesefragen/Orthopaedic Trauma Association.

Fracture details

The mechanism of injury was reported in 11 studies (126 patients)[28,29,32-40]. Of these, 62 (49.2%) had high-energy trauma, while 64 (50.8%) had low-energy trauma. The fracture location was reported in all studies, either by the authors or defined from the fracture classification. Twelve studies included TPFs only[28-34,36,38-41], one study had both PTFs (5 knees) and TPFs (25 knees)[37], and one study had only PTFs (11 knees)[35], giving a total of 158 (90.8%) TPFs and 16 (9.2%) PTFs. The fracture classification was reported in 13 studies[28-34,36-41] (163 patients), of which eight (78 patients) used the Schatzker classification (22 type II, 19 type III, 13 type IV, 17 type V, and 7 type VI). In contrast, five (85 patients) used the Arbeitsgemeinschaft für Osteosynthesefragen/Orthopaedic Trauma Association classification (5 type A, 52 type B, and 28 type C) (Table 1).

Surgery details

The time from injury to surgery was reported in nine studies[28,30,32,33,36,38-41], with a mean of 11.6 days, ranging from 1 day to 107 days. It should be noted that, across eight studies[28,30,33,36,38-41], the range was 1 day to 21 days, while in one study by Hesmerg et al[32], the range was from 15 days to 107 days. The surgical approach was reported in nine studies (108 patients)[28-30,33,35,37-39,41], all of which used a medial parapatellar approach; none reported an extensile approach. The knee prosthesis used in the surgeries were reported in all studies and were distributed according to their constraint level as follows: 86 (49.4%) posterior stabilized, 43 (24.7%) constraint condylar knee, 39 (22.4%) rotating hinge knee, and six (3.5%) cruciate retaining.

Details of the extras required during surgery were reported in 11 studies (103 patients)[28-30,32-34,36,38-41]. A tibial stem was inserted in 100 (97.1%) TKAs, and 26 (25.2%) had femoral stems. For bone defect reconstruction, the following were used on the tibial side: 21 (20.4%) metal augment (wedges or blocks), 15 (14.6%) metaphyseal cones, 14 (13.6%) bone graft, and three (2.9%) bone cement. The status of concomitant ORIF was reported in nine studies (89 knees)[28-30,33,34,36,38-40], of which 18 (20.2%) knees had a concomitant ORIF (Table 2).

Table 2 Surgical and implant details, mean ± SD.

Ref.	Time from injury to surgery (days)	Surgical approach	Type of prosthesis	Bone defect assessment	Use of extras	Concomitant ORIF (number of knees)
Abdelbadie et al[28], 2020	6.5 (1-21)	Medial parapatellar	22 PS	10 (45.5%) contained defect and 12 (54.5%) non contained defect	22 (100%) cementless long tibial stem, 6 (27.3%) bone graft and 4 (18.2%) metal wedge	6 (the fracture fragment was fixed by screws to act as structural bone graft)
Asikin et al[29], 2022	NR	Medial parapatellar	1 PS	NR	1 cementless tibial stem	Yes
Boureau et al[30], 2015	3.9 (1-11)	Medial parapatellar	10 RHK, one CCK	NR	11 cemented tibial stems	none
Haufe et al[31], 2016	NR	NR	24 RHK and 6 PS (MB)	NR	NR	NR
Hesmerg et al[32], 2024	58 (15-107)	NR	8 PS (6 MB), 2 CR, 2 RHK	NR	4 (33.3%) femoral stem, 12 (100%) tibial stem	NR
Huang et al[33], 2016	4 (2-6)	Medial parapatellar	3 PS femur and 3 CCK tibia	5 knees [3 contained and 2 non-contained (mean defect size was 3.2 mm)]	3 (100%) cemented tibial stem, bone defect was filled with polymethyl methacrylate or autologous bone	None
Kadakia et al[34], 2007	NR	NR	1 RHK	NR	Cemented stems in femur and tibia	None
Mirzatolooei et al[35], 2021	NR	Medial parapatellar	11 CCK	NR	NR	NR
Sabatini et al[36], 2023	5 ± 2 (2-9)	NR	6 PS and 5 CCK	NR	11 (100%) tantalum cones, wedges, cementless tibial stems	None
Sarzaeem et al[37], 2017	NR	Medial prepatellar	27 PS and 3 CCK	NR	NR	NR
Sivasubramanian et al[38], 2016	9 (6-12)	Medial parapatellar	2 PS and 1 LCCK	Intraoperatively, significant subchondral bone loss	3 (100%) tibial stems and tantalum cones- one (33.3%) femoral stem	2
Tapper et al[39], 2020	5.8 (1-16)	Medial parapatellar	2 RHK, 16 CCK, and 4 CR	NR	22 (100%) tibial stem, 19 (86.4%) femoral stem; 4 (18.2%) lateral or medial tibial augment, 1 (4.5%) tantalum cone	2
Vermeire and Scheerlinck[40], 2010	Three days (range: 1-6), one patient was operated upon after 2 weeks of trauma	NR	11 PS and 1 CCK	NR	12 (100%) tibial stem (cemented in two), 5 (41.7%) graft impaction, 2 (16.7%) augmentation blocks, one (8.3%) femoral stem	7
Wui et al[41], 2020	6 days and 15 days	Medial parapatellar	2 CCK	NR	2 (100%) tibia stem	NR

NR: Not reported; PS: Posterior stabilized; CR: Cruciate retaining; CCK: Constraint condylar knee; RHK: Rotating hinge knee.

Risk of bias assessment

All the studies demonstrated a high risk of bias, except for the two cohort studies, which showed a moderate risk of bias. This was mainly due to retrospective design, non-consecutive patient inclusion, limited follow-up, and incomplete reporting of complications or long-term outcomes (Table 3).

Table 3 Risk of bias assessment of the included studies.

Ref.	Patient selection	Outcome measures	Intervention description	Follow-up adequacy	Statistical clarity	Overall ROB
Abdelbadie et al[28], 2020	Moderate	Low	Low	Moderate	Moderate	Moderate
Asikin et al[29], 2022	High	Moderate	Moderate	High	Moderate	High
Boureau et al[30], 2015	High	Moderate	Low	High	Low	High
Haufe et al[31], 2016	High	Moderate	Low	High	Moderate	High
Hesmerg et al[32], 2024	Moderate	Low	Low	Moderate	Moderate	Moderate
Huang et al[33], 2016	High	Low	Low	High	Low	High
Kadakia et al[34], 2007	High	Moderate	Moderate	High	Low	High
Mirzatolooei et al[35], 2021	High	Low	Low	Moderate	Moderate	High
Sabatini et al[36], 2023	High	Low	Low	Moderate	Low	High
Sarzaeem et al[37], 2017	High	Low	Low	High	Low	High
Sivasubramanian et al[38], 2016	High	Moderate	Moderate	High	Low	High
Tapper et al[39], 2020	High	Moderate	Low	Moderate	Moderate	High
Vermeire and Scheerlinck[40], 2010	High	Moderate	Moderate	Moderate	Low	High
Wui et al[41], 2020	High	Moderate	Moderate	High	Moderate	High

Assessment was performed using the National Institutes of Health Quality Assessment Tool items for observational case series, cohort, and cross-sectional studies (https://www.nhlbi.nih.gov/health-topics/study-quality-assessment-tools). ROB: Risk of bias.

Outcomes

Postoperative weight-bearing status was reported in ten studies (120 patients)[28,30,31,33,35,37-41]. In seven studies, the authors allowed full weight-bearing (FWB) whenever tolerated[28,30,33,38-41], unless there was a reason for non-weight bearing, such as a concomitant skeletal injury. Meanwhile, in the remaining studies[29,35,37], the authors allowed immediate partial weight bearing. The mean follow-up for reporting the outcomes was 28.5 months, ranging from 1.3 months to 170.4 months.

Functional: The functional outcomes, including knee range of motion (ROM), were reported across all studies using various assessment tools. The knee ROM was reported in 11 studies (121 patients)[28,29,33-41], with a mean maximum knee flexion of 110.3 degrees (range, 90-140). The most commonly used tool for functional assessment was the Knee Society Score (KSS), including both components (knee and function), which was reported in eight studies (129 patients)[28,30,31,35-37,40,41]. Based on the definition of Miralles-Muñoz et al[42], a KSS ≥ 90 was an excellent outcome, 77-89 good, 76-65 fair, and < 65 poor. For the KS-Function Score: ≥ 85 was an excellent outcome, 73-84 good, 72-56 fair, and < 56 poor. The results from the eight studies[28,30,31,35-37,40,41] showed that the KSS component had a mean of 85.8 points (good outcome), with a range of 50 to 100. Meanwhile, the KS-Function Score component had a mean of 70.3 points (fair outcome), ranging from -20 to 100.

Radiological: Radiological outcomes were reported in eight studies (91 patients)[28-30,34,36-38,40]. In five studies (59 patients)[28,30,36,38,40], the final mechanical alignment was documented, and all knees achieved a mean mechanical alignment within the neutral range of ± 3 degrees at the hip-to-knee-to-ankle angle, except for three knees, which showed valgus alignment. In six studies (66 patients)[29,30,34,36,37,40], the authors reported no signs of radiolucencies or implant loosening. Fracture union status was reported in only two studies (4 patients)[29,38].

Complications: Complication incidents were reported in all studies, which occurred in 29 knees, giving an incidence of 16.7%. The most commonly occurring was periprosthetic joint infection (PJI) in 7 (4.02%) knees, followed by deep venous thrombosis in 4 (2.3%) knees, and each of the following occurred in three (1.7%) knees: Femoral periprosthetic fracture, limb malalignment, postoperative stiffness, wound healing issues, and hematoma formation. While implant loosening, retained cement particles, and extension lag occurred in one knee each (0.6%).

Revision: Data on revision were reported in 12 studies (132 patients)[28-30,33-41], and three (2.3%) patients required revision, two had a complete revision, one of them for stiffness and the other for PJI[39], while the third patient had only a debridement, antibiotics, and implant retention procedure for PJI[36] (Table 4).

Table 4 Details of the outcomes as reported in each study, mean ± SD.

Ref.	Follow up (months)	Weight-bearing status postoperatively	Outcomes
			Functional	ROM	Radiological	Complication	Revision
Abdelbadie et al[28], 2020	27.2 (24-32)	20 FWB (two NWB due to concomitant fractures)	Preoperative vs postoperative KS: 50.5 (42-64) vs 83 (50-100), preoperative vs postoperative KS Function Score: 62 (50-65) vs 84 (60-100)	Preoperative vs postoperative knee flexion: 32.6 degrees (20-40) vs 115 degrees (100-140); preoperative vs postoperative extension lag: 10.4 degrees (5-20) vs 1.4 degrees (0-5)	All were corrected to within a mean of ± 3 degrees neutral mechanical axis	Total of 4 (18.2%); 2 (9.1%) valgus alignment, 1 (4.5%) superficial wound infection, 1 (4.5%) femoral PPF	None
Asikin et al[29], 2022	6	PWB (walking frame training started three days postoperatively)	NR	Painless knee ROM of 0 degree to 90 degrees	Complete bone union with no sign of loosening	None	None
Boureau et al[30], 2015	31 (6-9)	FWB	KSS: 127, KS: 84, KS Function Score: 43, OKS: 35.7, preoperative vs postoperative Parker Score: 7.4 vs 5	NR (the authors reported the ROM for the whole group and did not report the ROM of tibia fracture patients separately)	There were no cases of radiolucency through the follow up period-mean HKA angle was 177 degrees (171 degrees to 180 degrees)	Total of 2: 1 stiffness required MUA, and 1 deep infection managed by irrigation drainage and prolonged antibiotic therapy	None
Haufe et al[31], 2016	27 (12-48)	NR	Mean KS: 81.1 (94-54), mean KS Function Score: 74.5 (100 to -20), and mean WOMAC score: 78.6 (96.2-36.7)	NR	NR	Total of 7: 3 wound healing deficit, 1 intraoperative PPF, 1 PJI, 1 retained intraarticular cement, 1 loosening	NR
Hesmerg et al[32], 2024	34.8 (16.8-170.4)	NR	KOOS-PS score 73 (59-93); OKS 43 (30-47), EQ-5D-5 L index 0.87 (0.69-1); EQ-5D VAS 80 (71-94)	NR	NR	One patient had stiffness requiring MUA	NR
Huang et al[33], 2016	32.3 (25-41)	5 FWB and 1 PWB	HSS score: 89.8 (85-94)	Knee flexion: 119.2 degrees (105 degrees to 130 degrees)	NR	None	None
Kadakia et al[34], 2007	6	NR	NR	Painless knee ROM 0 degree to 100 degrees	No loosening	PJI	None
Mirzatolooei et al[35], 2021	24	PWB	Preoperative vs postoperative Tegner Activity Scale: 2.2 ± 1.4 vs 4.3 ± 1.4, KS: 88.7 ± 5.4, KS Function Score: 59.4 ± 8.2, preoperative vs postoperative median HSS scale: 42 (16-58) vs 78 (72-91); preoperative vs postoperative pain severity: 65.2 ± 12.3 vs 35.5 ± 11.3	Preoperative vs postoperative median ROM: 85 degrees (55 degrees to 98 degrees) vs 97 degrees (95 degrees to 110 degrees)	NR	2 DVT	None
Sabatini et al[36], 2023	28 ± 14 (12-48)	NR	KS: 83 ± 16 (48 to 97), KS Function Score: 74 ± 15 (32 to 88); preoperative vs postoperative Parker’s Scale was 7.5 ± 1.4 (5-9) vs 5.6 ± 1.3 (3-8) (P < 0.05); FJS: 66 ± 14, (42 to 94)	Knee flexion was 116 degrees ± 7 degrees (110 degrees to 130 degrees), 10 patients had full knee extension, one patient had an extension lag of 10 degrees	No radiolucency, all had neutral alignment (HKA between ± 3 degrees); based on patellar indices, there were no cases of patella alta; only one patient had a CDI and BPI consistent with a patella baja (CDI = 0.54 and BPI = 0.56)	1 PJI, 1 extension lag of 10 degrees, 1 femoral PPF, 1 DVT	One required DAIR to treat PJI
Sarzaeem et al[37], 2017	54 ± 13 (36-72)	PWB	KS: 90.7 ± 6.5 (67-97), KS Function Score: 69.6 ± 8.8 (41-85); preoperative vs postoperative Tegner Activity Scale: 2.5 ± 1.2 (1-5) vs 3.5 ± 1.3 (2-6); the mean VAS for satisfaction: 8.1 ± 1 (6-10) and VAS Pain Score: 1.5 ± 1.2	Knee flexion range was significantly higher than the contralateral uninjured side: 106 degrees ± 13 degrees vs 120 degrees ± 8 degrees	No case of septic or aseptic loosening	None	None
Sivasubramanian et al[38], 2016	56 (18-82)	FWB	KSS: 88, no pain	Knee flexion: 122 degrees (105 degrees to 132 degrees); no fixed flexion deformity or hyperextension	Radiological fracture union at a mean of 3 months (2 months to 5 months); alignment of within 3 degrees of the mechanical axis was achieved in 2 patients (2.8 varus and 3.0 valgus)	1 valgus alignment of 7.2 degrees	None
Tapper et al[39], 2020	19 ± 16	FWB	KSS score: 160 ± 39; OKS 27 ± 11	Knee flexion: 109 degrees ± 16 degrees; extension deficit in three patients	NR	1 stiffness, 1 PJI	2
Vermeire and Scheerlinck[40], 2010	31 (1.3-81)	7 FWB, 3 PWB, 2 NWB (due to due to concomitant fractures)	Median KS: 78 (50-100), median KS Function Score: 58 (0-100); five patients had no pain at all	Knee flexion: 115.9 degrees (95 degrees to 130 degrees); no patients had hyperextension	Nine patients had a normal knee mechanical alignment (± 3 degrees HKA) and two showed a discrete valgus alignment compared to the contralateral side. No signs of loosening	3 developed a hematoma, 1 DVT, 1 PJI	None
Wui et al[41], 2020	22.3 ± 13.9	FWB	KS: 97 and 88; KS Function Score: 80 and 90	One patient (0 degree to 90 degrees) the other (0 degree to 130 degrees)	NR	None	None

ROM: Range of motion; FWB: Full weight bearing; NWB: Non-weight bearing; KS: Knee Score; PPF: Periprosthetic fracture; PWB: Partial weight bearing; NR: Not reported; MUA: Manipulation under anesthesia; OKS: Oxford Knee Score; WOMAC: Western Ontario and McMaster Universities Osteoarthritis Index; KOOS: Knee Injury and Osteoarthritis Outcome Score; VAS: Visual Analogue Scale; HSS: Hospital of special surgery; HKA: Hip to knee to ankle; PJI: Periprosthetic joint infection; DVT: Deep venous thrombosis; DAIR: Debridement, antibiotic irrigation, and implant retention; CDI: Caton-Deschamps index; BPI: Blackburn-Peel index; KSS: Knee Society Score.

Certainty of evidence (GRADE assessment)

The GRADE analysis showed that all evaluated outcomes, including functional results (KSS), postoperative knee flexion, complication rates, revision rates, and radiological alignment, were supported by very low-certainty evidence, downgraded primarily for serious risk of bias, imprecision, and inconsistency (Table 5).

Table 5 Grading of recommendations assessment, development and evaluation system of the evidence certainty level.

Outcome	Number of studies	Study design	Risk of bias	Inconsistency	Indirectness	Imprecision	Certainty
Functional outcomes (KSS)	12	10 case series + 2 cohorts	Serious	Not serious	Not serious	Serious	⊕◯◯◯: Very low
Range of motion (knee flexion)	12	10 case series + 2 cohorts	Serious	Not serious	Not serious	Serious	⊕◯◯◯: Very low
Complications (overall)	14	10 case series + 2 cohorts	Serious	Serious	Not serious	Serious	⊕◯◯◯: Very low
Revision rate	14	10 case series + 2 cohorts	Serious	Not serious	Not serious	Very serious	⊕◯◯◯: Very low
Radiological alignment	5	All were case series	Serious	Serious	Not serious	Very serious	⊕◯◯◯: Very low

KSS: Knee Society Score.

DISCUSSION

The current systematic review reported the results of 174 patients who had aTKA as their initial treatment for either PTFs or TPFs. Such a procedure was performed when pre-injury knee OA or severe osteopenia jeopardized the stability of the ORIF option. Various knee implants and extras were successfully used, and selection was primarily based on fracture classification and collateral ligament integrity. The aTKA resulted in acceptable functional outcomes, relatively lower complications, and revision rates.

Before discussing the results in more detail, it is mandatory to mention that these results should be interpreted cautiously, given the considerable ROB among the included studies and the overall quality of the evidence generated from those studies.

Indications and timing for aTKA

In the elderly population, some authors recommend ORIF for isolated medial or lateral TPFs without articular surface depression, which revealed acceptable outcomes[4,8,28]. In contrast, a clear indication for performing aTKA to manage PTFs or TPFs is debatable; however, patients with pre-existing knee OA or rheumatoid arthritis, severe osteoporosis, those who cannot follow the restricted western blot instructions, and those with complex fracture patterns are suitable candidates for aTKA[10,20,43].

A scoring system (Total Knee Replacement Indication Scoring System for knee fractures) was proposed by Quattrini et al[8] based on Arbeitsgemeinschaft für Osteosynthesefragen fracture classification after considering the patient age, pre-injury knee OA, medical comorbidities including diabetes, smoking, and malnutrition, and lastly, the Clinical Frailty Scale. Specific points were assigned to each item, and based on the total points, the patient had low, moderate, or high indications for aTKA if the score was 0-5, 5-8, or > 9, respectively.

Gupta et al[3] retrospectively evaluated 182 displaced TPFs in patients older than 60 years; 95.6% were initially treated with ORIF; however, within five years, 12% required secondary TKA. The authors reported that pre-injury knee OA and the severity of articular surface depression were independent risk factors for developing post-traumatic osteoarthritis and requiring TKA, and in the presence of such factors, aTKA should be considered. Interestingly, based on the patient’s pre-injury mobility and independence, Parratte et al[44] proposed that aTKA should be performed in patients with a Parker Mobility Score greater than six points.

Another crucial and controversial issue is how we define an aTKA and when such a surgery should be done after injury. Acute TKA for PTFs or TPFs is agreed upon as if it was the definitive surgery for these fractures to be differentiated from secondary or delayed TKA, which is performed after these fractures were treated, regardless of the type of initial management[21]. In the current review, two studies reported their view on this timing, where the surgery is considered aTKA, if it was performed within three weeks of the injury, according to Vermeire and Scheerlinck[40], while Hesmerg et al[32] extended such an interval to within four months after the fracture.

Furthermore, the timing till surgery is usually measured as the interval between the injury and aTKA; this interval varied in the current review as reported from nine studies[28,30,32,33,36,38-41]. The mean interval was 11.6 days, ranging from 1 day to 107 days; however, in eight studies[28,30,33,36,38-41], the range was from 1 day to 21 days, while in one study by Hesmerg et al[32] the range was from 15 days to 107 days. It is worth noting that the extended interval by Hesmerg et al[32] compared to other studies originated from the fact that the authors grouped patients who had TKA acutely after the injury and those who had TKA as the primary line of management within the first four months, this was clear when looking at the lower limit of the injury to surgery interval, which was 15 days, similar to other studies reporting the time interval to define aTKA.

Such a waiting period might be due to the patient’s medical or local soft-tissue conditions. Although none of the studies reported assessing the soft-tissue envelope or the reason for waiting such an interval, except for the study by Abdelbadie et al[28], which noted that the delay was to allow soft tissue to heal. However, it is well known from the trauma literature that waiting for some time to let the soft tissue heal and settle down is practiced by many surgeons[45].

Surgical details

Many authors suggested that the fundamentals of TKA revision surgery apply to performing an aTKA for managing PTFs, including surgical approaches, implant choice, and the need for extras (such as stems, augments, bone grafts, and so on). Selecting the best surgical strategy primarily depends on fracture extension, collateral ligament status, and the need for bone defect reconstruction[14,20,36,46].

Surgical approach: In the current review, the nine studies[28-30,33,35,37-39,41], that mentioned the surgical approach used the medial parapatellar approach, and none reported the need for an extensile approach. Parratte et al[46] suggested using an extensile approach, namely the extended sub-vastus approach, which is usually used in their revision TKA cases. In contrast, Tampere et al[14] reported that one approach has no advantage over the other, and surgeons should use their familiar approach.

Type of knee prosthesis: Some goals of performing aTKA for managing PTFs are to achieve a stable, pain-free, and mobile joint, allowing the patient to bear weight early and mobilize. These goals should be considered when selecting the proper knee prosthesis to use, especially the constraint level: Non-constraint (posterior stabilized and cruciate retaining), semi-constraint (constraint condylar knee type), and fully constraint (rotating hinge knee)[14,20,21,47]. Although some of the included studies reported that the knee prosthesis constraint level was determined based on collateral ligament status, none reported the exact selection criteria or whether this correlated with the fracture classification. Furthermore, the level of implant constraints varied across studies, with posterior stabilized prostheses used in nearly 50% of patients, which is the implant most commonly used during primary TKA. However, it is generally accepted that the fracture nature is closely related to the integrity of the collateral ligaments, particularly if the fracture directly affects one or both of their attachments. Moreover, rotating hinge knee prosthesis might be suitable for fractures with metaphyseal comminution in osteoporotic bone, marked laxity, or if there is a large bone defect[36,46].

Need for extras: The need for extras while performing aTKA was mainly to support the stability of the tibial implant or bone defect reconstruction. For this issue, Scott et al[48] reported the need to adopt the zonal fixation concept (originally described during revision TKA[49]), where obtaining tibial metaphyseal and diaphyseal fixation should be considered if epiphyseal fixation could not be achieved.

In the current review, of the 11 studies[28-30,32-34,36,38-41] reporting the use of extras (103 knees), 97% inserted tibial stems regardless of stem fixation method (cemented, cementless, or hybrid). Tibial stems offload the metaphyseal area until the fracture fully unites and the bone regains its strength, and surgeons may choose between cemented or cementless stems based on fracture extension and remaining bone stock; however, both techniques seem to work well[29,46,50]. Moreover, to improve metaphyseal area stability or reconstruct fracture-associated bone defects, various reconstruction strategies were used in the current review, namely metal augments (20.4%), metaphyseal cones (14.6%), bone grafts (13.6%), and bone cement (2.91%). The previously used options are well described in the TKA revision literature[49,51].

To ease dealing with the possible fracture-associated bone defects and deciding the needed fixation extent, Scott et al[48] adapted bone defect classification according to the Anderson Orthopaedic Research Institute to the Schatzker fracture classification. They suggested that Schatzker types I, II, III, and IV fractures are considered Anderson Orthopaedic Research Institute type 2A defects (single-plateau, uncontained defect). Therefore, these are amenable to management by acute metaphyseal fixation. In contrast, more severe injuries (Schatzker V and VI fractures) involving both tibial condyles could be considered as type 2B (both plateaus uncontained affecting) or type 3 (severe metaphyseal deficiency) defects, where diaphyseal fixation using stems should be added to the metaphyseal augmentation if aTKA was considered as the management option.

According to Huang et al[33], bone defects < 5 mm could be filled with bone cement, defects between 5 mm and 10 mm could be augmented with autogenous bone graft (usually obtained from the bony cuts), and for defects larger than 10 mm, metal wedges are required, accompanied by bone grafts. Furthermore, bone defect reconstruction should be protected by using a tibial stem. We found that Schatzker type II fractures were the most commonly reported among the included studies, consistent with previous reports[4,52]. However, this type of injury poses a challenge during reconstruction of the lateral plateau bone defect through the medial parapatellar approach (the predominant surgical approach in most studies). To address such a challenge, Scott et al[48] reported that asymmetric metaphyseal cones were used to reconstruct the defect, with promising results.

The need for a concomitant ORIF: The status of concomitant fracture osteosynthesis was reported in nine studies[28-30,33,34,36,38-40] in the current review, including 89 knees; however, it was only performed in 20% of the TKAs. The main benefit of performing a concomitant ORIF using plate and screws or screws alone is most evident when the fracture extends to the metaphyseal segment, where obtaining fracture stability and union at this area will lower the shearing forces and provide future stability of the tibial implant[21,29]. Moreover, osteosynthesis of these fractures could be an alternative to the use of costly extras such as metaphyseal cones[29]. Bohm et al[10] described a stepwise decision-making algorithm for managing osteoporotic fractures around the knee. They suggested optional supplementary fracture fixation for Schatzker type I-II-IV fractures based on the fragment size. Still, they highly recommend fracture osteosynthesis in combination with the tibial stem for bicondylar fractures or metaphyseal involvement (as in Schatzker types V and VI).

Outcomes

Functional: What guards against draining a robust estimate of the functional outcomes in the current review is the diversity of tools used for assessment; however, given the commonly used tool, the KSS, the functional outcomes are considered good and fair per the KS knee and function components, respectively[42,53]. Moreover, a mean knee flexion reaching about 110 degrees was reported in the current review, comparable to the range of motion obtained with primary TKA for knee OA[54].

In a systematic review by Makaram et al[13] comparing outcomes of aTKA vs delayed or secondary TKA (regardless of the initial management) after TPFs, the authors compared 121 in the acute group to 202 in the delayed group. Patients who had secondary TKA were significantly younger than those with aTKA (mean age: 61.3 years vs 72.2 years, P < 0.001). The functional outcomes were better in the aTKA group than in the delayed TKA group; however, the difference did not reach statistical significance [85.2% vs 79.9%, P = 0.359, 95% confidence interval (CI): 16.7 to 6.1]. The same conclusion was found in the study by Hesmerg et al[32]; however, the authors reported comparable functional and patient-reported outcomes in the aTKA patients compared with a matched cohort of elective TKA (for primary knee OA). At the same time, the results were worse when a group of delayed TKA patients was compared with the elective group.

Although we did not include comparisons of aTKA with other management modalities due to a lack of such comparisons within the included studies, Abdelbadie et al[28] compared the results of aTKA with ORIF; they reported similar hospital stay length but significantly better outcomes in the aTKA group as follows: Postoperative knee flexion, 115 degrees vs 95 degrees (P = 0.003), postoperative extension lag, 1.4 degrees vs 5.7 degrees (P = 0.005), postoperative KS-Knee Score 83 vs 70 (P = 0.00), and postoperative KS-Function Score 84 vs 72 (P = 0.00).

In contrast, Gupta et al[6] evaluated outcomes after operative (47 knees) and nonoperative (20 knees) management of TPFs in patients older than 60 years. After a mean follow up of 3.5 years, regardless of their initial management, they reported lower outcomes than a matched cohort of the same age and gender. The TPFs cohort showed significantly worse EQ-5D-3 Utility Scores, although their scores were higher when comparing their pre-injury status. They found a significant decline in the Oxford Knee Score compared with pre-injury levels. The decrease in patient-reported outcomes and functional outcomes could be attributed to delayed weight-bearing, loss of independence, and complications associated with operative management, which are not encountered with aTKA for managing TPFs in this age group.

Radiological: Regarding radiological outcomes, only five studies[28,30,36,38,40] reported postoperative alignment, with most patients achieving neutral mechanical alignment within the accepted range of 180 degrees ± 3 degrees hip to knee to ankle; in contrast, none reported individual component (tibial and femoral) alignment. Furthermore, five studies reported no signs of radiolucencies or implant loosening until the last follow up. These outcomes align with those obtained during primary TKA and after TPFs’ operative management[4,54].

In a study by Donovan et al[4] evaluating the outcomes after managing TPFs in 220 patients having a mean age of 74 years (range 60-100). Low-energy trauma was the leading cause of fractures (71%), and 61% of the fractures involved the lateral tibial plateau. Interestingly, 60% of the patients were treated nonoperatively. Of the operatively managed patients, only 3% underwent aTKA, and the majority (91%) were treated by ORIF. The authors reported that the knee joint alignment, measured as the anatomical femorotibial angle, had a mean of 173.0 degrees ± 5.0 degrees for all patients, and was 173.0 degrees ± 5.3 degrees vs 173.1 degrees ± 4.7 degrees for operatively vs nonoperatively managed patients, respectively, which is comparable to the results shown in the current review.

Complications and revisions: Complication incidence was reported in all of the studies, where the total incidence was about 17%, with PJI and deep venous thrombosis being the most frequently occurring complications. Hematoma formation, reported in three knees, may be attributed to the amount of soft-tissue injury associated with TPFs.

Data on the need for revision surgeries and their indications were reported in 12 studies[28-30,33-41], and only three patients required revision, giving an overall revision incidence of 2.3%: One for PJI, one for knee stiffness, and the last patient had PJI but was managed by debridement, antibiotics, and implant retention. One patient had aseptic loosening, but until the last follow up, the patient required no revision.

A systematic review by Pander et al[22], who evaluated the outcomes of secondary TKA for post-traumatic osteoarthritis after TPFs, included 162 patients from five studies, where 77% of those patients were initially treated operatively; they reported a complication incidence reaching up to 36%, where postoperative stiffness and PJI were the most commonly occurring. Furthermore, revision TKA surgery was required in 14 (8.6%) patients, six for PJI and three for aseptic loosening. It is worth mentioning that 12 (7.4%) patients required manipulation under anesthesia for persistent postoperative stiffness.

A recent study by Wagener et al[55], based on data from the German Arthroplasty Registry comparing the risk and causes of revision after TKA in more than ten thousand patients who had previous osteosynthesis to those who had osteotomies, although the authors included osteosynthesis of fractures of the distal femur and patella besides PTFs, they reported a higher risk of revision in this group (hazard ratio = 1.81, 95%CI: 1.52-2.15; P < 0.001), furthermore, the PJI risk was also higher (hazard ratio = 1.62, 95% confidence interval: 1.21-2.19).

Abdelbadie et al[28] reported fewer complications with aTKA than ORIF (4 vs 8); however, the difference did not reach statistical significance (P = 0.15). According to Makaram et al[13], the complication rate was significantly lower in aTKA patients. Furthermore, the need for reoperation or revision surgery was also lower with aTKA, 10% compared to 19% in the secondary TKA group (odds ratio = 2.14, 95%CI: 1.08 to 4.25, P = 0.26).

Advantages of aTKA

Some advantages of performing aTKA for TPFs, especially in older patients, should be mentioned: First is overcoming the challenging issue of osteoporotic bone, where ORIF might fail. During aTKA, this issue was mitigated by using extras such as augments and stems to improve implant stability, leading to early rehabilitation and ambulation; second is early mobilization and weight bearing, which are beneficial for function and help prevent complications associated with prolonged recumbency, such as DVT. In the current systematic review, nearly all patients were allowed to start weight bearing as tolerated early postoperatively, and the incidence of DVT was reported at an incidence of 2.3%. In contrast, Donovan et al[4] reported that weight-bearing was limited for the first six weeks in 90% of operatively managed patients; third, early mobilization will partially prevent loss of autonomy, especially in geriatric patients, which was proven in two studies included in the current systematic review[30,36], where the authors showed that Parker’s Mobility Scale decreased in the last follow up compared to the preoperative values; and lastly, aTKA avoids the reported higher complications and revision rate associated with ORIF and secondary TKA[9,22,32].

Limitations

Although the data derived from the included studies seem encouraging, and some advantages are associated with selecting aTKA as the primary management option for selected patients and specific injury patterns, these data should be interpreted cautiously in light of the following limitations: First, the serious ROB across nearly all the included studies led to weak, less reliable evidence. This is mainly attributed to the nature of the study design, as most of the studies were either case series or reports lacking control or comparative groups, making it challenging to attribute the acceptable outcomes directly to the intervention (aTKA) rather than other confounding factors (e.g., patient selection, surgeon skill, post-operative protocol, and so on); second, the probable heterogeneity originating from variations in surgical technique, type of prosthesis used, the use of stems and other extras, and different techniques for bone defect reconstruction. This “performance bias” makes it difficult to pool results or identify a single best technique, rather than tailoring the decision after considering the patient and fracture factors; third, formulating clear indications for performing aTKA to treat PTFs rather than other management options was difficult, as most studies reported varied indications and perspectives based on the authors’ experience and clinical judgement; fourth, performing quantitative analysis and making robust recommendations based on the obtained results was not possible, which was also attributed to the study design and its relatively small sample sizes; fifth, few studies reported overall limb alignment postoperatively, and none reported on individual component alignment, especially on the tibial side, which is a crucial factor in predicting the risk of future failure or aseptic loosening[56]; sixth, we could not properly evaluate functional outcomes due to inconsistent reporting, particularly as different assessment scores were used; and last is the relatively short follow-up duration, which limits the ability to detect longer-term complications, revision rates, and implant longevity.

CONCLUSION

PTFs, either intra-articular or extra-articular, might pose a challenge to the treating surgeon, especially when occurring in older patients with concomitant knee OA, osteoporosis, and severe metaphyseal comminution. Performing aTKA as the primary management for such fractures is suitable after considering patient and fracture variables. Various levels of knee prosthesis constraint may be used depending on fracture type, collateral ligament integrity, and the extent of the bone defect. Furthermore, extras such as stems and augments are needed to improve initial implant stability and to reconstruct bone defects. The functional, complications, and revision outcomes are considered acceptable. However, while the included studies collectively suggest that aTKA may offer promising short-term outcomes for selected PTFs, the strength of the evidence remains limited and underscores the need for well-designed prospective studies with larger sample sizes and longer follow-up.