Is endoprosthetic replacement of the proximal femur appropriate in the comorbid patient?

Similar risks of complications and reoperation rates in proximal femur megaprostheses for oncological and non-oncological indications

PURPOSE

Proximal femur megaprostheses (PFMPs) are used to manage large bone defects in both non-oncological indications (NOI) and oncological indications (OI). However, little is known about the comparative risks of reoperation and functional outcomes between these groups. This study aimed to evaluate the cumulative incidences of reoperation and functional results of PFMPs between NOI and OI.

METHODS

This retrospective, monocentric cohort study included 109 implants between 2005 and 2020 (NOI, n = 42; OI, n = 67). Competing risk analysis was used to estimate and compare cumulative incidence of reoperation and complications, with death as a competing event. The Musculoskeletal Tumour Society Score (MSTS) was retrospectively assessed to compare functional outcomes.

RESULTS

The estimated cumulative incidence of reoperation at ten years did not statistically differ: 33.5% for NOI vs. 32.7% for OI (HR = 0.90, 95% CI (0.42-0.95), p = 0.791). The estimated cumulative incidence of complications at ten years did not statistically differ (HR = 1.50, 95%CI (0.80-2.80), p = 0.204). The MSTS score at ten years was significantly higher in the OI group (78.2% ± 19.5) compared to the NOI group (48.3% ± 10.9) (p = 0.012).

CONCLUSION

PFMPs for NOI demonstrate a comparable risk of reoperation to OI, but with lower long-term functional outcomes.

Factors Associated With Failure Following Proximal Femoral Replacement for Salvage Hip Surgery for Nononcologic Indications

BACKGROUND

Proximal femoral replacement (PFR) is used when extensive proximal femoral bone loss is encountered during revision total hip arthroplasty. However, further data on 5-to-10-year survivorship and predictors of failure are needed. Our aim was to assess the survivorship of contemporary PFRs used for nononcologic indications and determine factors associated with failure.

METHODS

A single-institution retrospective observational study was conducted between June 1, 2010 and August 31, 2021 for patients undergoing PFR for non-neoplastic indications. Patients were followed for a minimum of 6 months. Demographic, operative, clinical, and radiographic data were collected. Implant survivorship was determined via Kaplan-Meier analysis of 56 consecutive cemented PFRs in 50 patients.

RESULTS

At a mean follow-up of 4 years, the mean Oxford Hip Score was 36.2 and patient satisfaction was rated at an average of 4.7 of 5 on the Likert scale. Radiographic evidence of femoral-sided aseptic loosening was determined in 2 PFRs at a median of 9.6 years. The 5-year survivorship with all-cause reoperation and revision as end points was 83.2% (95% Confidence Interval [CI]: 70.1% to 91.0%) and 84.9% (95% CI: 72.0% to 92.2%), respectively. The 5-year survivorship was 92.3% (95% CI: 78.0% to 97.5%) for stem length > 90 mm compared to 68.4% (95% CI: 39.5% to 85.7%) for stem length ≤ 90 mm. A construct-to-stem length ratio (CSR) ≤ 1 was associated with a 91.7% (95% CI: 76.4% to 97.2%) survival, while a CSR > 1 was associated with a 73.6% (95% CI: 47.4% to 88.1%) survival.

CONCLUSION

A PFR stem length ≤ 90 mm and CSR > 1 were associated with increased rates of failure.

Megaprosthesis in Non-Oncologic Settings-A Systematic Review of the Literature

Modular megaprostheses (MPs) are commonly used after bone-tumor resection, but they can offer a limb salvage solution in massive bone defects. The aim of this systematic review of the Literature is to provide a comprehensive data collection concerning the use of MPs in non-oncologic cases, and to provide an overview of this topic, especially from an epidemiologic point of view. Three different databases (PubMed, Scopus, and Web of Science) were searched for relevant articles, and further references were obtained by cross-referencing. Sixty-nine studies met the inclusion criteria, reporting on cases of MP in non-oncologic cases. A total of 2598 MPs were retrieved. Among these, 1353 (52.1%) were distal femur MPs, 941 (36.2%) were proximal femur MPs, 29 (1.4%) were proximal tibia MPs and 259 (10.0%) were total femur MPs. Megaprostheses were most commonly used to treat periprosthetic fractures (1158 cases, 44.6%), in particular in the distal femur (859, 74.2%). Overall, complications were observed in 513 cases (19.7%). Type I (soft tissue failures) and type IV (infection) according to the Henderson classification were the most frequent (158 and 213, respectively). In conclusion, patients with severe post-traumatic deformities and/or significant bone loss who have had previous septic complications should be considered as oncologic patients, not because of the disease, but because of the limited therapeutic options available. The benefits of this treatment include relatively short operative times and immediate weight-bearing, thus making MP particularly attractive in the lower limb.

Does a novel bridging collar in endoprosthetic replacement optimise the mechanical environment for osseointegration? A finite element study

Introduction: Limb-salvage surgery using endoprosthetic replacements (EPRs) is frequently used to reconstruct segmental bone defects, but the reconstruction longevity is still a major concern. In EPRs, the stem-collar junction is the most critical region for bone resorption. We hypothesised that an in-lay collar would be more likely to promote bone ongrowth in Proximal Femur Reconstruction (PFR), and we tested this hypothesis through validated Finite Element (FE) analyses simulating the maximum load during walking. Methods: We simulated three different femur reconstruction lengths (proximal, mid-diaphyseal, and distal). For each reconstruction length one in-lay and one traditional on-lay collar model was built and compared. All reconstructions were virtually implanted in a population-average femur. Personalised Finite Element models were built from Computed Tomography for the intact case and for all reconstruction cases, including contact interfaces where appropriate. We compared the mechanical environment in the in-lay and on-lay collar configurations, through metrics of reconstruction safety, osseointegration potential, and risk of long-term bone resorption due to stress-shielding. Results: In all models, differences with respect to intact conditions were localized at the inner bone-implant interface, being more marked in the collar-bone interface. In proximal and mid-diaphyseal reconstructions, the in-lay configuration doubled the area in contact at the bone-collar interface with respect to the on-lay configuration, showed less critical values and trends of contact micromotions, and consistently showed higher (roughly double) volume percentages of predicted bone apposition and reduced (up to one-third) percentages of predicted bone resorption. In the most distal reconstruction, results for the in-lay and on-lay configurations were generally similar and showed overall less favourable maps of the bone remodelling tendency. Discussion: In summary, the models corroborate the hypothesis that an in-lay collar, by realising a more uniform load transfer into the bone with a more physiological pattern, creates an advantageous mechanical environment at the bone-collar interface, compared to an on-lay design. Therefore, it could significantly increase the survivorship of endo-prosthetic replacements.

Apparent trends in the use of femoral megaprostheses: an analysis from the National Joint Registry

BACKGROUND

Megaprosthetic replacement (MPR) of the femur is typically reserved for salvage or oncological reconstruction. Presently little is known about the provision of femoral MPRs performed nationally, the trends in indications for their use, and their outcomes beyond published unit-level data. Although the National Joint Registry (NJR) collects data as part of a mandatory arthroplasty audit process, MPR data entry on this platform is thought to be inconsistent. The aim of this study is to determine current trends for femoral MPR procedures as submitted to the NJR.

METHODS

Data for all procedures submitted to the NJR using the following implants were extracted: METS (Stanmore/Stryker), MUTARS (Implantcast), Segmental (Zimmer), GMRS (Stryker) and MEGA C (LINK). Pseudoanonymized data were analyzed through the NJR's research Data Access Portal and are reported using descriptive statistics.

RESULTS

A total of 1781 procedures were identified. Submitted cases increased for primary and revision hip and knee categories over the study period, although they plateaued in recent years. MPR implants were most commonly used in revision hip arthroplasty procedures. MPR use for the management of peri-prosthetic fractures has increased and now represents the most commonly reported indication for MPR use in both hip and knee revision categories. Few centers submitted large MPR case volumes (which were noted to be lower than published unit case series, indicating NJR under-reporting), and the vast majority of centers submitting MPR cases did so in low volume.

CONCLUSIONS

Due to the limitations identified, reported case volumes must be interpreted with caution. An MPR-specific NJR data entry form has been developed to allow more accurate and tailored reporting of MPR procedures, to support specialist service provision, and to provide meaningful data for future research.

Proximal femoral replacement for non-neoplastic conditions: a systematic review on current outcomes

Proximal femoral replacement (PFR) is a well-established treatment for neoplasia of the proximal femur. The use of this surgical technique for non-neoplastic conditions has increased over the years. We carried out a systematic review of the literature to study the indications, complications, and functional results when PFR is used for non-neoplastic conditions. Twenty-seven studies were included in the review with a total of 828 PFRs with a mean follow-up of 50 months (range 1-225 months). The main indications were infection (28%), periprosthetic fracture (27%), aseptic loosening (22%), and fracture (16%). The rate of reoperation was 20.3% overall. The overall revision rate was 15.4%. The main complications were dislocation (10.2%) and infection (7.3%). After 2010, the rates of reoperation (25.5% versus 18.2%), loosening (9.4% versus 3.2%), and dislocation (15.7% versus 7.9%) were lower than before 2010. The 30-day mortality ranged from 0% to 9%. The hip function scores improved post-surgery. In conclusion, the use of PFR in non-neoplastic conditions remains a marginal tool, associated with low direct mortality and high complication rates, but we expect its use to increase in the near future.

Worse Outcomes Are Associated With Proximal Femoral Replacement Following Periprosthetic Joint Infection

BACKGROUND

Proximal femoral replacements (PFRs) are often used in the setting of severe bone loss. As osteolysis has become less common, PFR may be used to address other causes of bone loss such as infection or periprosthetic fracture. The aim of this study is to investigate the clinical outcomes of PFR for non-neoplastic conditions.

METHODS

A retrospective review of 46 patients undergoing PFR at a single institution was performed. The electronic records were reviewed to extract relevant information including the reason for use of PFR, surgical variables, follow-up, and complications. Survivorship curves were generated and differences in survivorship were evaluated using the log-rank test. Radiographic evaluation was also performed.

RESULTS

Using revision as an endpoint, the Kaplan-Meier analysis of the entire cohort demonstrated a survival rate of 74% at 1 year and 67% at 5 years. Patients with a preoperative diagnosis of periprosthetic joint infection demonstrated the lowest survivorship with a failure rate of 47%. Furthermore, a high dislocation rate at 17.4% (n = 8) was observed. The use of dual-mobility articulation was effective in reducing dislocation.

CONCLUSION

PFR is a valuable reconstructive option for patients with massive proximal femoral bone loss. This study demonstrates that patients with periprosthetic joint infection who undergo PFR reconstruction are at very high risk of subsequent failure, most commonly from reinfection and instability. The use of a dual-mobility articulation in association with PFR appears to help mitigate risk of subsequent dislocation.

The Use of Megaprostheses in Nononcologic Lower-Extremity Total Joint Arthroplasty: A Critical Analysis Review

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As the number of primary total joint arthroplasty (TJA) procedures continues to rise, megaprostheses have found an emerging role in more complex revision arthroplasty cases that require additional reconstruction, stability, and restoration of function.

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Megaprosthesis options have evolved: in addition to cemented prostheses, cementless and even hybrid fixation designs optimize longevity. Proximal femoral replacement (PFR), distal femoral replacement (DFR), proximal tibial replacement (PTR), and total femoral replacement (TFR) are all limb salvage options in the setting of substantial bone loss, poor bone quality, and soft-tissue compromise.

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Dislocation is one of the most common complications after PFR, likely due to the loss of soft-tissue integrity, most notably the hip abductor musculature from the greater trochanter. The utilization of dual-mobility constructs, larger femoral heads, elevated acetabular liners, and constrained acetabular liners may reduce the risk of instability and improve overall hip function.

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Patients with megaprostheses may be more prone to periprosthetic joint infection and surgical site infection given multiple variables, such as the lengthy nature of the surgical procedure, prolonged wound exposure, extensive soft-tissue dissection and resection, poor soft-tissue coverage, and poorer host status.

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Despite advances in technology, complication and revision rates remain high after megaprosthesis reconstruction. Therefore, thorough attention to patient-specific factors must be considered for appropriate use of these constructs.

Megaprostheses in Nononcologic Hip and Knee Revision Arthroplasty

Megaprostheses as a means of limb salvage originated in orthopaedic oncology, and implant evolution was initially driven by developments within this field. Improvements in imaging modalities and in chemotherapeutics prolonged patient survival and promoted a transformation in the surgeon's mentality from salvage operation to functional limb reconstruction. As primary arthroplasty operations became more popular, megaprostheses found new utility in hip and knee revision arthroplasty. In this capacity, these implants provided much needed alternatives to traditional arthroplasty revision options for addressing massive bone loss and complex periprosthetic fractures. The indications for megaprostheses continue to expand with advances in design, stability, and overall longevity. Thus, greater numbers of orthopaedic surgeons in arthroplasty and traumatology have to be familiar with this technology. Importantly, each anatomic location presents unique considerations for reconstruction; however, additional variables such as the quantity of bone loss, the quality of remaining bone stock, and fracture type also influence implant selection. Ultimately, there is still much to be optimized in the use of megaprostheses for hip and knee revision arthroplasty. High multifactorial complication and revision surgery rates compared with conventional prostheses make these implants for many a "last resort" option.

Reconstruction of proximal femoral bone loss using circumferential structural allograft during total hip arthroplasty in a young patient

Management of proximal femoral bone loss during hip arthroplasty in young patients is a complex problem due to the need to provide a joint with an increased longevity. While proximal femoral replacement (PFR) would be an easier solution, they are associated with poorer hip scores and decreased prosthesis survival rates which are not ideal while managing young patients. We present a case of proximal femoral bone loss in a young female - following multiple failed osteosynthesis surgeries aimed at addressing a pathological sub-trochanteric fracture - managed successfully with a circumferential allograft during total hip arthroplasty. While there is many literature reporting the use of circumferential allografts during revision hip surgery, this is the first case to the best of our knowledge where we are reporting its successful use in a complex primary hip arthroplasty case. Our successful outcome shows that reconstruction of proximal femoral bone loss using allografts in young patients should be considered prior to use of PFR in them.

Cemented Proximal Femoral Replacement for the Management of Non-Neoplastic Conditions: A Versatile Implant but Not Without Its Risks

BACKGROUND

The demand for revision arthroplasty continues to grow. Proximal femoral bone loss poses a significant challenge to surgeons and proximal femoral replacements (PFRs) are one option to address this problem. The aim of our study is to assess the reoperation, complication, and mortality rates following PFR for treatment of non-neoplastic conditions.

METHODS

A retrospective observational study was conducted of a consecutive group of patients treated with a PFR for non-neoplastic conditions between 2010 and 2018. Mortality was confirmed using the Irish national death events publication service.

RESULTS

Over the 8-year study period, 79 PFRs in 78 patients were performed. Mean age of patients was 78.3 years (standard deviation 11.9), of which 37.2% were male. Periprosthetic fracture was the most common indication for PFR (63.3%). The 30-day mortality rate was 7.6% (6 patients), of which bone cement implantation syndrome occurred in 4 patients. One-year mortality was 12.7%. Complications occurred in 22.8%.

CONCLUSION

A cemented PFR is a versatile prosthesis in the armamentarium of a revision arthroplasty surgeon that allows immediate full weight-bearing. However, it may appropriately be considered a last resort procedure that poses specific risks that must be explained to patients and family. We present the short-term outcomes on one of the largest series of PFR to date.