Reconstruction with modular megaprostheses for sarcomas of the lower extremity

The history of resection prosthesis

INTRODUCTION

The purpose of this historical review is to highlight the progression and development of prosthetic reconstruction with a focus on the modular distal femur with hinged total knee arthroplasty.

METHOD

Scientific literature was searched for descriptions of endoprosthetic reconstruction of the extremities to provide a thorough overview of the subject, focusing the research on the evolution of limb salvage of the distal femur.

RESULTS

After the first works of Gluck and Giordano, with ivory and metal and the pioneer shoulder prosthesis by Pean in the late 1890s, a great advancement was brought by reconstructions performed for injured soldiers of the Great War. By the 1940s, replacement of all the main joints had been attempted, and documented.

DISCUSSION

Walldius in the 1950s developed a fully constrained hinge knee, offering for the first time a consistent and replicable method of substituting the joint. In 1953, Shiers' prosthesis allowed for good flexion and extension. Stanmore and GUEPAR group prosthesis in the 1960s were the first to have a different right and left side model. The rotating hinge was developed in 1978 by Walker, with the innovative concept of six degrees of freedom. Between 1979 and 1982, Kotz developed the modular segmental replacement that, added to a fixed hinge knee, permitted the revolutionary creation of the modern distal femur replacement.

CONCLUSION

The study of the materials and mechanical solutions that was brought to the modern distal femur resection prosthesis is a good example of a virtuous multidisciplinary teamwork between orthopaedic surgeons, anatomists, and biomechanical engineers.

Distal femoral replacement - Does length matter? Mid-term results for distal femoral replacements

BACKGROUND

Review of mid-term results (five years) for tumour and revision arthroplasty surgery using the Stanmore METS® distal femoral replacement.

METHODS

Data were collected retrospectively for 90 patients for procedures performed between 2002 and 2019. Kaplan-Meier survivorship for implant was estimated at five years post-op. Endpoints for survivorship analysis included revision for any cause and as per Henderson classification. Log rank test was used to compare implant survival for different categorical variables. Musculo-Skeletal Tumour Society (MSTS) score was used to estimate function.

RESULTS

Overall implant survival at five years was 76% (95% CI 66-86). Implants with a short body (<= 45 mm) had significantly better implant survival [87% (95% CI 78-99)] compared to those with larger bodies [63% (95% CI 48-82)] (logrank test, p = 0.031). There was no significant difference in implant survival for tumour and revision arthroplasty patients (logrank test, p = 0.61). Mean MSTS scores (median follow-up = 3.5 years) for tumour and revision arthroplasty patient were 71% and 63% respectively (Wilcoxon rank test, p < 0.05). Higher total number of surgeries was a significant predictor of patient mortality [HR = 0.7 (95% CI 0.49-0.99)]. Longer bodies were a significant predictor of implant failure [HR = 3.2 (95% CI 1.05-10.53), p < 0.05].

CONCLUSION

Overall outcome of Stanmore METS® distal femoral replacement at five years following tumour and revision arthroplasty reconstruction is comparable to the other implants.

How is the outcome of the Limb Preservation System™ for reconstruction of hip and knee?

BACKGROUND

Despite tremendous advantages in the development and application of megaprostheses in tumour and revision surgery, complications are still not infrequently observed. Only two studies investigating the outcome of the LPS™ system in the proximal femur and distal femur/proximal tibia have been published thus far. Herein, mid-term implant survival rates one of the largest cohort of patients treated with the LPS™-system are presented aiming tp answer: 1) How is the outcome of the LPS™ system in the proximal femur and distal femur/proximal tibia? 2) Which factors are associated with altered implant survival? 3) What is the cumulative risk of complications according to Henderson?

HYPOTHESIS

The LPS™-system is associated with high complication rates that depend on implant site, with infections being most common.

PATIENTS AND METHODS

Fifty-seven patients who received the LPS™-system at the proximal femur (n=31), distal femur (n=21) and proximal tibia (n=5) between 2004 and 2010 for oncological (n=40) or non-oncological (n=17) causes, were retrospectively included. Median follow-up was 5.0 years (range, 0-12.4 years). Complications were classified according to Henderson into instability/soft tissue failure (type 1), aseptic loosening (type 2), structural failure (type 3), periprosthetic infection (type 4), tumour progression (type 5). Competing-risk-analyses were applied to estimate implant survival with death as the competing event.

RESULTS

Twenty-six patients (45.6%) developed a complication, of whom 9 (29.0%) had a proximal femoral and 17 (65.4%) a distal femoral/proximal tibial implant. Type 4 complications were most common (n=11), followed by type 3 (n=6, including 2 yoke-fractures), type 1 and 2 (n=4 each), and type 5 (n=1). The only factor associated with the development of complications in the multivariate model was a distal femoral/proximal tibial implant (hazard-ratio: 7.418, 95% confidence-interval: 2.193-26.096, p=0.001), irrespective of reason for reconstruction and use of muscular flaps. The cumulative-incidence of failure including all complications was 34.3%, 40.7% and 67.1% at 3, 5 and 10 years, respectively.

DISCUSSION

The LPS™-system may be used for proximal femoral reconstructions both in the oncological and non-oncological setting. Rates of complications are higher in our cohort than reported in literature for other, comparable, megaprosthesis systems. Especially in the distal femur/proximal tibia, complication rates were high, partially attributable to the former implant design leading to fractures of the yoke-mechanism. As the implant has been remodelled after these issues became evident, there is no objection to use this megaprosthesis system today.

LEVEL OF EVIDENCE

IV, Observational Study.

Is unicondylar osteoarticular allograft still a viable option for reconstructions around the knee?

BACKGROUND

Unicondylar osteoarticular allografts (UOAs) represent a possible technique for reconstructing massive bone defects around the knee when only one condyle is affected. The aim of this retrospective study is to evaluate the outcome of UOAs and describe the possible salvage procedures in case of graft failure.

METHODS

Twenty-five deep-frozen UOAs were implanted at Rizzoli Orthopedic Institute (Bologna, Italy). Twenty-two followed bone tumor resection, two cases were post-traumatic defects and one case followed UOA failure. Mean age at surgery was 33years (range: 15 to 63). Eighteen UOAs were in distal femur, seven in proximal tibia.

RESULTS

Three patients died (only one because of the tumor). One UOA was removed for chondrosarcoma relapse and one for allograft fracture. Mean overall survival with UOA failure as a primary endpoint was 129months (range 12 to 302), with differences in the femur (85%) and in the tibia (40%) at 150months. Six UOAs had to be converted into knee prostheses due to osteoarthritis after a mean follow-up of 146months. No complications were recorded in UOAs converted into knee prostheses after a mean three year follow-up. Fourteen patients with UOAs still in place at the last follow-up (mean 123months) were radiologically and functionally evaluated: no correlation was found between function and the degree of osteoarthritis.

CONCLUSIONS

In selected cases, UOAs offer good clinical results and postpone the need for knee prosthesis. Despite short-term encouraging results, longer-term follow-up is needed in order to evaluate the outcome of knee prosthesis after UOA.