While extra-articular resection (EAR) of the knee and shoulder joint is associated with poorer clinical outcomes, the oncological and functional risks of EAR of the hip joint are unknown. We aimed to compare these risks between EAR of the hip joint and intra-articular resection (IAR).

We conducted a comparative study of 75 patients who underwent en-bloc tumour resection and limb-salvage reconstruction for bone sarcomas of the peri-acetabulum between 1996 and 2016. We divided patients into two groups for analyses; EAR (n = 21) and IAR (n = 54).

There was no statistical difference in oncological outcomes; the 5-year cumulative incidence of disease-specific death was 34% and 35% in the EAR and IAR groups, respectively (p = 0.943), and the 5-year cumulative incidence of LR was 26% and 34%, respectively (p = 0.482). The most common complications were dislocation (28%) and deep infection (28%); there was equally no difference between the groups. The mean Musculoskeletal Tumour Society score was 66% and 65% in the EAR and IAR groups, respectively (p = 0.795), and were significantly lower in patients with deep infection (52% vs. 69%; p = 0.013). In a sub-analysis on the outcomes in patients who underwent PI-uninvolved PII-resection for chondrosarcoma, no major differences in oncologic and functional outcomes were confirmed.

Patients undergoing EAR and limb-salvage reconstructions of the hip joint have undistinguishable oncological, clinical and functional outcomes compared to those undergoing IAR and reconstructions. If preoperative imaging suggests articular tumour involvement, there appears to be no detrimental effect of undertaking EAR to optimise local control.

The study of tumor extension in knee osteosarcomas is an essential diagnostic tool that helps determine the surgical approach. Magnetic resonance imaging (MRI) is the key component in this decision-making process, but the interpretation of signals can be difficult because peritumoral edema and inflammation may be mistaken for the tumor.

There is a discrepancy between MRI and histopathology findings in the assessment of joint involvement in pediatric osteosarcomas of the knee.

All children who underwent an extra-articular resection for an osteosarcoma of the knee between 2007 and 2016 were included. This was indicated if there was at least one of the following MRI signs: presence of articular effusion, involvement of either the peripheral capsuloligamentous structures, central pivot or patella, or lesion abutting the articular cartilage.

Nine patients were operated on with a mean age of 13±2.7 years. There were at least two of the described signs, mainly the involvement of the peripheral capsuloligamentous structures (78%) and central pivot (56%). The histopathology confirmed that the resection margins were healthy in all cases, but the indication for extra-articular resection could have been avoided in 89% of them.

MRI is the current gold standard for assessing tumor extension, but the signs contraindicating the transarticular approach remain poorly defined. Joint effusion detected by clinical or radiological assessment is the least reliable one. It seems that the tumor's proximity to the articular cartilage, as long as there is no loss of continuity in the latter, or its extension into the central pivot should no longer be considered as relevant signs. The involvement of the peripheral capsuloligamentous structure remains an indication criterion because oncologic resection is otherwise impossible, and the risk of false-negative histopathologic diagnoses is higher. Other MRI sequences could better assess the true extension into the joint space.

IV, retrospective study.

Primary bone tumours are uncommon, with sarcomas accounting for < 0.2% of all malignancies. The survival rate of primary bone sarcomas has significantly improved due to (neo)adjuvant therapy, while improved surgical techniques and development of new prostheses have shifted the surgical focus from amputation to limb preservation in the vast majority of patients. A wide variety of surgical options are available for the treatment of primary bone tumours which depend upon histological diagnosis, their appearance at the time of presentation and response to any (neo)adjuvant therapy as required. This review is intended to help radiologists familiarise themselves with the management of primary appendicular bone tumours and expected normal postoperative appearances for the various surgical techniques, and to recognise potential complications.

Extensor mechanism function after a proximal tibial tumour excision is the major determining factor for the limb function. However, problems of extensor lag, delayed healing and poor functional outcomes exist with the previous methods of its reconstruction. We describe a novel technique of using a patellar stainless steel (SS) wire to reconstruct the extensor apparatus of the knee in non-porous coated implants and examine the functional outcome and associated complications.

This was a retrospective analytical interventional study. Twenty-six patients operated between 2011 and 2019 were included. Extensor lag measured at 6 months and 12 months postoperative, total range of motion at 12 months and Musculoskeletal Tumor Society (MSTS) score at the final visit were retrieved. Complications that occurred during the follow up period were noted. Patellar position was measured using comparative patellar-position-ratio.

Mean extensor lag at 6 months was 18.5° which improved to 8.7° at 12 months. Patellar malposition and deep infection were found to be the causes of poor functional outcome. A patellar-position-ratio between 0.9 and 1.1 led to a well-functioning extensor apparatus. Four patients underwent above-knee amputations. Deep infection and amputations reduced the MSTS score. An SS wire give way after 6 months did not affect the extensor power. A medial gastrocnemius flap reduced the infection rates.

Patellar SS wiring is an effective technique for reconstructing the knee extensor apparatus following a proximal tibial tumour excision mega-prosthesis. Proper position of the SS wire prevents wire-related complications. For a well-functioning extensor apparatus, use of a gastrocnemius flap cover intra-operatively is pertinent along with lack of infection for a pain-free, stable and mobile limb.

This study aimed to evaluate the thickness of the remaining patellar bone stock following extra-articular knee resection (EKR) preserving the extensor mechanism in human cadaveric knee joints.

A total of 14 human cadaveric knee joints (8 men and 2 women) were dissected, and the patellar thickness from the joint capsule insertion to the anterior cortex of the patella was measured using an electronic caliper. The mean age of the cadavers was 37 years (range=28-50). Measurements were performed by an anatomist and an orthopedic surgeon. As the total number of the cadavers was not enough to show the patellar thickness with sampling (sex and age), we endeavored to supplement the content with magnetic resonance images (MRI). Accordingly, the patellar bone thickness was also measured on axial MRI scans of 100 adult and 25 pediatric knees of patients (71 women and 54 men; mean age=36 years; age range=7-67 years) admitted to our hospital in whom meniscal tears were suspected. The rate of specimens with remaining patellar thickness of less than 10 mm after presumed resection was evaluated. The macroscopic measurements in cadavers and MRI measurements in adult knees were compared statistically.

The mean thickness of the residual patellar bone of the cadaver dissections following a presumed EKR preserving the extensor mechanism was 8.2 mm (range=3.4-15.8). Additionally, in 71.4% (10/14) of the cadaveric knees, the thickness of residual patellar bone was less than 10 mm. In MRI scans, the average thickness of residual patella after presumed resection was 8.6 mm (range: 3.6-16) in adult knees and 6.9 mm (range: 3.4-10) in pediatric knees, and the residual patellar thickness less than 10 mm after presumed resection was determined in 72% of all MRI scans. Macroscopic measurements in cadaveric knees were statistically similar to MRI scan measurements in adult knees (p=0.765, Mann-Whitney U test).

Evidence from this study revealed that the thickness of the remaining patellar bone stock after EKR preserving the extensor mechanism may be low. A preoperative assessment with MRI can guide the surgeon to select the appropriate method for knee resection in order to prevent from the complications of resected patella.

The aim of this study was to determine the oncologic, functional, and clinical outcomes after the extra-articular resection and limb-salvage reconstruction of the hip joint.

A retrospective study of 34 patients who underwent extra-articular resection of the hip joint for bone sarcomas between 1996 and 2016 was conducted. The primary tumor site was pelvis in 26 patients (76%) and femur in eight (24%).

The surgical margins achieved were clear in 31 (91%) patients, and seven (21%) patients developed local recurrence; mostly occurring in pelvic tumors (n = 6). The 3-year overall survival was 63% with a median follow-up of 38 months (range, 5-219), which showed no statistical difference in tumor location. The most common complication was deep infection (n = 7) and dislocation (n = 7), mostly seen in pelvic tumors. Implant failure was seen in two patients with pelvic tumors, while no failure was noted in patients with femoral tumors. The median Musculoskeletal Tumour Society score was 69%; 67% for pelvic tumors and 73% for femoral tumors (P = .535).

Despite complex surgery, extra-articular resection of the hip joint can achieve oncologically and functionally acceptable outcomes. While tumors of the pelvis are associated with a higher incidence of infection and local recurrence after resection, resection of tumors involving the femur are well tolerated.

The proximal tibia is one of the most challenging anatomic sites for extremity reconstructions after bone tumor resection. Because bone tumors are rare and large case series of reconstructions of the proximal tibia are lacking, we undertook this study to compare two major reconstructive approaches at two large sarcoma centers.

The purpose of this study was to compare groups of patients treated with endoprosthetic replacement or osteoarticular allograft reconstruction for proximal tibia bone tumors in terms of (1) limb salvage reconstruction failures and risk of amputation of the limb; (2) causes of failure; and (3) functional results.

Between 1990 and 2012, two oncologic centers treated 385 patients with proximal tibial resections and reconstruction. During that time, the general indications for those types of reconstruction were proximal tibia malignant tumors or bone destruction with articular surface damage or collapse. Patients who matched the inclusion criteria (age between 15 and 60 years old, diagnosis of a primary bone tumor of the proximal tibia treated with limb salvage surgery and reconstructed with endoprosthetic replacement or osteoarticular allograft) were included for analysis (n = 149). In those groups (endoprosthetic or allograft), of the patients not known to have reached an endpoint (death, reconstructive failure, or limb loss) before 2 years, 85% (88 of 104) and 100% (45 of 45) were available for followup at a minimum of 2 years. A total of 88 patients were included in the endoprosthetic group and 45 patients in the osteoarticular allograft group. Followup was at a mean of 9.5 (SD 6.72) years (range, 2-24 years) for patients with endoprosthetic reconstructions, and 7.4 (SD 5.94) years for patients treated with allografts (range, 2-21 years). The following variables were compared: limb salvage reconstruction failure rates, risk of limb amputation, type of failures according to the Henderson et al. classification, and functional results assessed by the Musculoskeletal Tumor Society system.

With the numbers available, after competitive risk analysis, the probability of failure for endoprosthetic replacement of the proximal tibia was 18% (95% confidence interval [CI], 10.75-27.46) at 5 years and 44% (95% CI, 31.67-55.62) at 10 years and for osteoarticular allograft reconstruction was 27% (95% CI, 14.73-40.16) at 5 years and 32% (95% CI, 18.65-46.18) at 10 years. There were no differences in terms of risk of failures at 5 years (p = 0.26) or 10 years (p = 0.20) between the two groups. Fifty-one of 88 patients (58%) with proximal tibia endoprostheses developed a reconstruction failure with mechanical causes being the most prevalent (32 of 51 patients [63%]). A total of 19 of 45 osteoarticular allograft reconstructions failed (42%) and nine of 19 (47%) of them were caused by early infection. Ten-year risk of amputation after failure for endoprosthetic reconstruction was 10% (95% CI, 5.13-18.12) and 11% (95% CI, 4.01-22.28) for osteoarticular allograft with no difference between the groups (p = 0.91). With the numbers available, there were no differences between the groups in terms of the mean Musculoskeletal Tumor Society score (26.58, SD 2.99, range, 19-30 versus 27.52, SD 1.91, range, 22-30; p = 0.13; 95% CI, -2,3 to 0.32). Mean extension lag was more severe in the endoprosthetic group than the osteoarticular allograft group: 13.56° (SD 18.73; range, 0°-80°) versus 2.41° (SD 5.76; range, 0°-30°; p < 0.001; 95% CI, 5.8-16.4).

Reconstruction of the proximal tibia with either endoprosthetic replacement or osteoarticular allograft appears to offer similar reconstruction failures rates. The primary cause of failure for allograft was infection and for endoprosthesis was mechanical complications. We believe that the treating surgeon should have both options available for treatment of patients with malignant or aggressive tumors of the proximal tibia. (S)he might consider an allograft in a younger patient to achieve better extensor mechanism function, whereas in an older patient or one with a poorer prognosis where return to function and ambulation quickly is desired, an endoprosthesis may be advantageous.

Level III, therapeutic study.

We reviewed the oncological and functional outcomes of patients treated for a primary sarcoma possibly involving the knee joint and present an algorithm to guide treatment. The records of 76 patients who had a primary bone or soft tissue sarcoma possibly invading the knee between 1996 and 2012 were identified. Mean age and follow-up was 32 years (9-74) and 64 months (12-195), respectively. Patients were grouped according to the resection (Intra-articular [IAR] vs. Extra-articular [EAR] vs. Amputation/rotationplasty) for survival and functional outcomes. Overall 5 and 10 year survival was 61% and 53%, respectively. No differences in survival were found between the 3 groups (p = 0.55). Sixteen patients developed local recurrence with no difference between the groups. Mean MSTS score was 24.5 (12-30). Mean flexion at final follow-up was 106° (70-130°). We conclude that EAR of the knee allows for good oncologic and functional outcomes but with an increased risk of complications compared to IAR. Intra-operative assessment of joint involvement can be done in patients where joint infiltration by the tumour is not clear to avoid an unnecessary EAR. For chondrosarcoma patients with joint involvement, an EAR should be carefully considered because they present a significantly higher local recurrence risk.

Extra-articular resection is necessary to obtain a wide margin for primary osteosarcomas invading the knee joint, and the limb is often reconstructed using a prosthesis. Here, outcomes of extra-articular and intra-articular procedures were compared.

Between 1999 and 2012, 14 patients with osteosarcoma underwent extra-articular excision (n = 6; ages 23-65 years; mean follow-up 82.8 months) or intra-articular excision (n = 8; ages 8-58 years; mean follow-up 96.4 months). In the extra-articular group, there was one Enneking Stage IIA case and five Enneking Stage IIB cases. No local recurrences were noted in either group.

Patient outcomes were as follows (extra-articular cases vs. intra-articular cases): continuous disease-free (2 vs. 7), alive with disease (2 vs. 0) and death from disease (1 vs. 1). Average Musculoskeletal Tumor Society functional scores were 69.4% (range 63.3-83.3%) and 88.3% (range 70.0-96.7%) in the extra-articular and intra-articular groups, respectively, constituting a significant difference (P < 0.05). The 5-year oncological overall survival exceeded 80% in both groups. Amputation was necessary for one patient in the extra-articular group. The 5-year event-free prosthesis survival rates in the extra-articular and intra-articular groups were 33.3 and 75.0%, respectively (P < 0.05).

The extra-articular excision group developed more complications than the intra-articular excision group, as a result of extensive bone and muscle excision. The limb survival rates were similar in both groups. Our results suggest that extra-articular resection was a necessary and clinically acceptable procedure.

We evaluated the clinical results and complications after extra-articular resection of the distal femur and/or proximal tibia and reconstruction with a tumour endoprosthesis (MUTARS) in 59 patients (mean age 33 years (11 to 74)) with malignant bone or soft-tissue tumours. According to a Kaplan-Meier analysis, limb survival was 76% (95% confidence interval (CI) 64.1 to 88.5) after a mean follow-up of 4.7 years (one month to 17 years). Peri-prosthetic infection was the most common indication for subsequent amputation (eight patients). Survival of the prosthesis without revision was 48% (95% CI 34.8 to 62.0) at two years and 25% (95% CI 11.1 to 39.9) at five years post-operatively. Failure of the prosthesis was due to deep infection in 22 patients (37%), aseptic loosening in ten patients (17%), and peri-prosthetic fracture in six patients (10%). Wear of the bearings made a minor revision necessary in 12 patients (20%). The mean Musculoskeletal Tumor Society score was 23 (10 to 29). An extensor lag > 10° was noted in ten patients (17%). These results suggest that limb salvage after extra-articular resection with a tumour prosthesis can achieve good functional results in most patients, although the rates of complications and subsequent amputation are higher than in patients treated with intra-articular resection.

Reconstruction of the extensor mechanism after resection of the proximal tibia is challenging, and several methods are available. A medial gastrocnemius flap commonly is used, although it may be associated with an extensor lag. This problem also is encountered, although perhaps to a lesser extent, with other techniques for reconstruction of the extensor apparatus. It is not known how such lag develops with time and how it correlates with functional outcome.

We therefore (1) assessed patellar height with time, (2) correlated patellar height with function using the Musculoskeletal Tumor Society (MSTS) score, and (3) correlated patellar height with range of motion (ROM) after medial gastrocnemius flap reconstruction.

Sixteen patients underwent tumor endoprosthesis implantation and extensor apparatus reconstruction between 1997 and 2009 using a medial gastrocnemius flap after sarcoma resection of the proximal tibia. These patients represented 100% of the population for whom we performed extensor mechanism reconstructions during that time. The minimum followup was 2 years (mean, 5 years; range, 2-11 years). Fourteen patients were alive at the time of this study. We used the Blackburne-Peel Index to follow patellar height radiographically with time. Functional outcomes were assessed retrospectively using the MSTS, and ROM was evaluated through active extensor lag and flexion.

Eleven patients had patella alta develop, whereby the maximal patellar height was reached after a mean of 2 years and then stabilized. More normal patellar height was associated with better functional scores, a smaller extensor lag, but less flexion; the mean extensor lag (and flexion) of patients with patella alta was 17° (and 94°) compared with only 4° (and 77°) without.

In our patients patella alta evolved during the first 2 postoperative years. Patella alta is associated with extensor lag, greater flexion, and worse MSTS scores. Surgical fixation of the patellar tendon more distally to its anatomic position or strict postoperative bracing may be advisable.

Level IV, clinical cohort study. See the Guidelines for Authors for a complete description of levels of evidence.

Previous studies reported variable outcome of proximal tibial resections and reconstructions. Therefore, we evaluated the survival, Musculoskeletal Tumor Society (MSTS) function, and complications of patients and reconstructions in this location.

We reviewed the files of 225 patients with proximal tibial tumors treated with proximal tibial resection, fixed or rotating hinge megaprosthetic reconstruction and extensor mechanism reattachment using sutures, mechanical clamping, artificial ligaments, and/or gastrocnemius flap from 1985 to 2010 (mean follow-up, 90 months; median, 56; range, 2-294). Survival of patients and reconstructions, type of hinge, extensor mechanism reconstruction, MSTS function, and complications were analyzed.

Survival of patients with sarcomas was 68% and 62% at 5 and 10 years. Survival of megaprosthetic reconstructions was 82% and 78% at 5 and 10 years, without any difference between fixed and rotating hinge megaprostheses. MSTS function was significantly better in univariate and multivariate analysis for rotating compared to fixed hinge megaprostheses, without any difference between the types of extensor mechanism reconstructions. Most common complications were infection (12%), aseptic loosening (6%), and extensor mechanism rupture (3%).

Rotating hinge proximal tibia megaprosthetic reconstructions have better function compared to fixed hinge, regardless of the type of extensor mechanism reconstruction.

Intraarticular extension of a tumor requires a conventional extraarticular resection with en bloc removal of the entire knee, including extensor apparatus. Knee arthrodesis usually has been performed as a reconstruction. To avoid the functional loss derived from the resection of the extensor apparatus, a modified technique, saving the continuity of the extensor apparatus, has been proposed, but at the expense of achieving wide margins. In tumors involving the joint cavity, the entire joint complex including the distal femur, proximal tibia, the full extensor apparatus, and the whole inviolated joint capsule must be excised. We propose a novel reconstructive technique to restore knee function after a true extrarticular resection.

The approach involves a true en bloc extraarticular resection of the whole knee, including the entire extensor apparatus. We performed the reconstruction with a femoral megaprosthesis combined with a tibial allograft-prosthetic composite with its whole extensor apparatus (quadriceps tendon, patella, patellar tendon, and proximal tibia below the anterior tuberosity).

We retrospectively reviewed 14 patients (seven with bone and seven with soft tissue tumors) who underwent this procedure from 1996 to 2009. Clinical and radiographic evaluations were performed using the MSTS-ISOLS functional evaluation system. The minimum followup was 1 year (average, 4.5 years; range, 1-12 years).

We achieved wide margins in 13 patients (two contaminated), and marginal in one. There were three local recurrences, all in the patients with marginal or contaminated resections. Active knee extension was obtained in all patients, with an extensor lag of 0° to 15° in primary procedures. MSTS-ISOLS scores ranged from 67% to 90%. No patients had neurovascular complications; two patients had deep infections.

Combining a true knee extraarticular resection with an allograft-prosthetic composite including the whole extensor apparatus generally allows wide resection margins while providing a mobile knee with good extension in patients traditionally needing a knee arthrodesis.

Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Limb salvage in tumor surgery has encouraged the development of megaprostheses. However, reattaching the ligamentum patellae poses a particular problem: avulsion and/or extensor lag may lead to poor function. We describe a new technique of patellar ligament reconstruction. The technique involves reattachment of the patellar ligament to the tibial tuberosity of the proximal tibial megaprosthesis, which has a porous surface created, and the repair is protected with a cerclage wire through the patella and the prosthesis. In 10 consecutive patients, the range of motion averaged 95 degrees (median, 90 degrees ; range, 70 degrees -120 degrees ), and the mean extension lag averaged 4 degrees (median, 0 degrees ; range, 0 degrees -20 degrees ). We had one case of patellar ligament avulsion. This technique resulted in good quadriceps function and a low incidence of complications.

Level IV, therapeutic study.