Anterior knee pain in anterior cruciate ligament reconstruction using bone-patellar tendon-bone graft and autologous bone grafting

Abstract

BACKGROUND

Anterior cruciate ligament (ACL) reconstruction using bone-patellar tendon-bone (BPTB) autografts remains the gold standard for young, active individuals due to its superior biomechanical strength and bone-to-bone healing. However, donor site morbidity, particularly anterior knee pain (AKP), limits its utilization despite its advantages. Various techniques have been proposed to reduce AKP, but they show variable outcomes and several limitations.

AIM

To assess the incidence and severity of AKP following BPTB ACL reconstruction using an autologous bone grafting technique.

METHODS

We conducted a retrospective observational study of 24 patients aged 20-45 years, who had primary ACL reconstruction with BPTB grafts. During surgery, autologous cancellous bone generated from tunnel drilling was used to fill the patellar and tibial donor site voids after graft fixation. All patients were followed up for at least twelve months. Using the Kujala Anterior Knee Pain Score, clinical outcomes were evaluated, including the pain-specific subcomponent.

RESULTS

With scores ranging from 86 to 100, the average overall Kujala score was 95.67 ± 4.01. No patient scored below 85. There was no complication such as patellar fracture, tibial tuberosity fracture, or infection. Grouped data showed 20.8% of patients scored 100, whereas 54.2% scored between 95 and 99, and 25% scored between 86 and 94. One patient (4.2%) had an 8/10 pain subcomponent, whereas 23 patients (95.8%) had a 10/10.

CONCLUSION

This procedure is easy to incorporate into routine surgical practice, cost-effective and reproducible without requiring extra incisions or raising the patient’s surgical expenses. Excellent short-term results back up this technique.

Key Words: Knee; Anterior knee pain; Anterior cruciate ligament; Bone patellar tendon bone; Autograft

Core Tip: This study highlights that by utilizing bone already available from femoral and tibial tunnel drilling during bone-patellar tendon-bone anterior cruciate ligament reconstruction, routine bone grafting of donor tibial and patella harvest site defects is a simple and reproducible technique that results in excellent functional outcomes with minimal donor site morbidity. This method offers a cost-effective approach. The high Kujala scores and absence of clinically significant anterior knee pain in this cohort support the integration of this technique into standard surgical practice.

INTRODUCTION

Anterior cruciate ligament (ACL) tears are among the most frequently encountered orthopaedic injuries, particularly in young individuals and athletes involved in pivoting sports[1-5]. Surgical reconstruction using autologous grafts is the standard treatment for restoring knee stability and function[6-9]. Among the available graft options, the bone-patellar tendon-bone (BPTB) autograft remains a popular choice due to its superior biomechanical properties, including bone-to-bone healing, high tensile strength, and reliable graft fixation[7,10-12].

However, despite these advantages, BPTB grafts are often associated with donor site morbidity, particularly anterior knee pain (AKP), which can significantly hinder postoperative rehabilitation, delay return to sports, and reduce overall patient satisfaction[6,13-15]. The incidence of AKP following BPTB graft harvest has been reported in multiple studies to be as high as 48%[16-18].

The etiology of AKP after BPTB ACL reconstruction is multifactorial[14,19,20]. Several strategies have been proposed to address this issue. While some studies report reduced morbidity with these techniques, concerns remain regarding graft strength, donor site healing, and increased surgical costs[13,14,21].

This study aims to evaluate the incidence and severity of AKP following BPTB ACL reconstruction using an autologous bone grafting technique. Cancellous bone harvested during femoral and tibial tunnel drilling was used to fill the patellar and tibial bone defects, as described by Krishna et al[22]. We assessed the clinical utility of this approach in reducing donor site morbidity by analyzing functional outcomes and AKP scores in patients who underwent this grafting method.

MATERIALS AND METHODS

Study design

This retrospective observational study was conducted after obtaining ethical approval from the institutional ethics committee. The study size included all consecutive patients who underwent ACL reconstruction with the novel bone grafting technique between July 2022 and April 2024, as identified from the hospital record database. Patients meeting the inclusion criteria were contacted telephonically from July 15 to July 30, 2025, and included in the study after obtaining verbal informed consent. The inclusion criteria comprised adults aged 20-45 years who underwent primary ACL reconstruction using a BPTB graft with autologous bone grafting. Only patients with a minimum postoperative follow-up of twelve months were included. Exclusion criteria were revision ACL surgeries, multiligamentous knee injuries, and cases with incomplete medical records or inadequate follow-up data.

Surgical technique

All patients underwent ACL reconstruction using a BPTB autograft. An oblique incision from the centre of the patella to a point 1 cm distal and 1.5 cm medial to the tibial tuberosity was used to approach the patellar tendon. The central third of the patellar tendon was harvested along with bony plugs from the patella and tibial tuberosity. While harvesting bone plugs, a 1 cm wide saw blade was used. The cuts were made adequately so that the bone plugs could be harvested only by levering out with a small osteotome. No hammering of the osteotome was done. Autologous cancellous bone generated during drilling of the femoral and tibial tunnels was collected using a wash cannula. The collected bone was separated from saline using simple sedimentation and decantation. It was packed into the patellar and tibial harvest site defects after fixation of the graft using interference screws. The same technique was described by Krishna et al[22]. All procedures were performed by the same orthopaedic surgical team.

Outcome measures

Postoperative functional assessment was conducted using the Kujala Anterior Knee Pain Score. The pain component of the Kujala score was also assessed independently.

Statistical analysis

Data were analyzed using Statistical Package for the Social Sciences version 30. Continuous variables are expressed as mean ± SD, categorical variables are presented as n (%). Given the retrospective nature of the study without a control group, comparative hypothesis testing was not performed. Instead, our results were benchmarked against well documented rates of AKP from the literature.

RESULTS

Twenty-four patients were included in the study. The mean age was 28.54 ± 5.17 years, with 11 males (45.83%) and 13 females (54.17%). The mean total Kujala score was 95.67 ± 4.01, indicating a high level of knee function and minimal anterior knee discomfort across the cohort. The scores ranged from 86 to 100, and importantly, none of the patients had a score below 85, which is generally considered the threshold for clinically significant AKP (Table 1). Grouped data showed 20.8% patients scored 100, 54.2% scored between 95 and 99, 16.7% scored between 90 and 94 and 8.3% scored between 86 and 89. Focusing specifically on the pain subcomponent within the Kujala scale, 23 out of 24 patients (95.8%) reported a perfect score of 10 out of 10, reflecting an absence of AKP during routine activities. Only one patient (4.2%) scored 8 out of 10, indicating mild anterior knee discomfort (Table 2). No intraoperative or postoperative complications were observed in the study population. There were no cases of patellar fracture, tibial tuberosity fracture, wound infection, or donor site complications such as persistent pain, numbness, or delayed healing.

Table 1 Distribution of total Kujala anterior knee pain score.

Kujala score range	Number of patients	Percentage
100	5	20.8
95-99	13	54.2
90-94	4	16.7
86-89	2	8.3

Functional outcome: Kujala Anterior Knee Pain Score (scale from 0 to 100). A score of 100 indicates no complaint or functional limitation, while threshold of clinically significant anterior knee pain is widely considered to be below 85.

Table 2 The pain specific subcomponent of Kujala Anterior Knee Pain Score.

Pain score	Number of patients	Percentage
10/10	23	95.8
8/10	1	4.2

The Kujala score pain subcomponent scores range from 10 (no pain) to 0 (severe, continuous pain).

DISCUSSION

AKP is a well-documented complication following ACL reconstruction with BPTB autografts[14,23-26]. It has a complex pathophysiology and remains one of the key deterrents for surgeons and patients considering BPTB grafts, despite their superior biomechanical advantages[14,18]. Previous literature has consistently reported AKP in up to 48% of cases following such reconstructions[16,17]. The cause of AKP postoperatively can be traced to direct trauma during tendon harvesting, stripping of periosteum, damage to the infrapatellar nerve, formation of scar tissue[18,20], and most importantly, the presence of bone defects at the donor site[27-30]. These osseous voids are believed to act as stress concentrators, leading to altered load distribution and microfractures, potentially exacerbating pain[19,24,31].

Across studies using BPTB autografts without donor-site bone grafting (Table 3)[16,17,23-25], the reported incidence of AKP at approximately 2 years varies considerably, ranging from 16.1% in the series by Aune et al[23] to 48.4% in that of Guglielmetti et al[16], with Shaieb et al[24] reporting 41.9%. With extended follow-up, Sajovic et al[17] documented an incidence of 48.0% at 11 years, indicating that AKP may persist over time. By contrast, studies incorporating donor-site bone grafting have consistently demonstrated lower rates. Brandsson et al[25] reported a 12.5% incidence at 2 years following grafting of the patellar defect, while the present study, employing routine grafting of both patellar and tibial harvest sites, observed an incidence of only 4.2% at 1 year.

Table 3 Reported anterior knee pain after bone-patellar tendon-bone anterior cruciate ligament reconstruction (literature comparison).

Ref.	Technique	Number of patients	Follow-up (years)	Anterior knee pain incidence
Brandsson et al[25], 1998	BPTB, bone grafting (only patella defect)	29	2	12.5
Aune et al[23], 2001	BPTB, no bone grafting	29	2	16.1
Shaieb et al[24], 2002	BPTB, no bone grafting	31	2	41.9
Sajovic et al[17], 2011	BPTB, no bone grafting	32	11	48.0
Guglielmetti et al[16], 2021	BPTB, no bone grafting	31	2	48.4
Present study	BPTB + donor-site bone grafting	24	1	4.2

Present study: Original research and data presented in this paper. BPTB: Bone-patellar tendon-bone.

Several approaches have been explored to manage this complication[32-35]. Some have utilized bone grafts from separate donor sites to fill the void left after the graft harvest. The use of synthetic bone substitutes has also been studied, but results have been inconsistent due to limited biological integration and slower incorporation into native bone. The technique used in this study addresses these limitations by employing autologous bone obtained from tunnel drilling during the same surgical procedure. This method offers immediate availability, eliminates the need for additional incisions, and promotes superior biological incorporation.

The technique was originally described by Krishna et al[22]. Our study presents the first clinical outcome data, using the same technique. We observed a mean Kujala score of 95.67 ± 4.01, with all patients scoring above 85% and 95.8% achieving a perfect pain score of 10/10. These findings indicate an extremely low incidence of clinically significant AKP and suggest that the autologous bone grafting of tibial and patellar bone defects is both effective and safe. Figure 1 showing the healing of both tibial and patellar defects in one of the patients.

Figure 1 Axial non-contrast computed tomography cuts showing healed patellar and tibial tuberosity donor sites in a patient after 1 year. A: Patellar site; B: Tibial Tuberosity site.

From a cost-effectiveness perspective, this technique offers immense benefits, especially in resource-limited settings. Unlike synthetic grafts or secondary autograft harvests, this method requires no additional surgical steps or expenses.

However, the study is not without limitations. Its retrospective design carries an inherent potential for selection and recall bias. Furthermore, being a single-centre study with a relatively small sample size, the generalizability of the findings may be limited. The grafting technique itself requires additional operative time for harvesting cancellous bone graft and filling the donor-site voids. Additionally, this study lacks a control group, which limits direct comparative statistical analysis of this technique’s benefits. However, we have presented our outcome results against the well-documented historical rates of AKP from the literature (Table 3)[16,17,23-25]. Finally, the one year follow up is shorter than that of many comparative studies. While this timeframe is sufficient to show early morbidities and pain that is important for patient rehabilitation, larger prospective trials with longer follow-up are needed to validate these findings and perhaps standardize this technique.

CONCLUSION

This study demonstrates that bone grafting of donor tibial and patella harvest site defects during BPTB is a simple, biologically effective, and reproducible technique that results in excellent functional outcomes with minimal donor site morbidity. By utilizing bone already available from femoral and tibial tunnel drilling, this method offers a cost-effective approach without added surgical complexity. The high Kujala scores and absence of clinically significant AKP in this cohort support the integration of this technique into standard surgical practice. Future prospective studies with larger sample sizes and longer follow-up durations are warranted to confirm these findings and further establish this technique as a standard of care in ACL reconstruction using BPTB grafts.