Survivorship, complications, and outcomes following distal femoral arthroplasty for non-neoplastic indications

Characteristics and Epidemiology of Megaprostheses Infections: A Systematic Review

BACKGROUND

Megaprostheses were first employed in oncological orthopedic surgery, but more recently, additional applications have arisen. These implants are not without any risks and device failure is quite frequent. The most feared complication is undoubtedly the implants' infection; however, the exact incidence is still unknown. This systematic review aims to estimate in the current literature the overall incidence of megaprosthesis infections and to investigate possible risk/protective factors.

METHODS

We conducted a systematic search for studies published from July 1971 to December 2023 using specific keywords. To be included, studies needed to report either the megaprosthesis anatomical site, and/or whether the megaprosthesis was coated, and/or the surgical indication as oncological or non-oncological reasons.

RESULTS

The initial literature search resulted in 1281 studies. We evaluated 10,456 patients and the overall infection rate was 12%. In cancer patients, the infection rate was 22%, while in non-oncological patients, this was 16% (trauma 12%, mechanical failure 17%, prosthetic joint infections 26%). The overall infection rates comparing coated and uncoated implants were 10% and 12.5%, respectively.

CONCLUSIONS

The number of megaprosthesis implants is increasing considerably. In traumatological patients, the infection rate is lower compared to all the other subgroups, while the infection rate remains higher in the cancer patient group. As these devices become more common, focused studies exploring epidemiological data, clinical outcomes, and long-term complications are needed to address the uncertainties in prevention and management.

Survivorship, complications, and outcomes following distal femoral replacement for neoplastic indications

Background

Distal femoral replacements (DFRs) are excellent treatment options for limb salvage procedures in patients who have bone loss secondary to neoplasm. Multiple studies report adequate survivorship and complication rates following DFR implantation, primarily for non-neoplastic indications. However, current literature regarding neoplasm-specific reports is often limited by sample size, survivorship, and patient reported outcome measurements. Therefore, we sought to examine patients who received a DFR for a neoplastic indication at multiple tertiary academic centers. Specific outcomes analyzed included: (1) revision-free survival, (2) medical/surgical complications, and (3) Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS JR).

Methods

All patients who underwent a DFR for a neoplastic indication were retrospectively reviewed. A total of 29 knees were included for various neoplastic indications. Outcomes of interest included: post-operative thromboses, pneumonia, dislocations, periprosthetic joint infections (PJIs), aseptic loosening, osteolysis, emergency department visits, inpatient readmissions, and revision surgeries. Patient-reported outcome measure (PROM) collected included: Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS JR).

Results

Revision-free survivorship was 72.4 % at 23 months with radiographic follow-up. PJI was the most common post-operative complication, affecting 3 knees (10.3 %). The mean number of emergency department visits and inpatient readmissions averaged less than one per patient (0.63 and 0.41, respectively). KOOS JR scores improved markedly among from baseline to final follow-up (44.1-57.8).

Conclusion

The use of DFR led to satisfactory medium-term clinical outcomes with an acceptable complication rate for this challenging group of patients. The marked improvement in patient satisfaction for this patient population gives a promising outlook for patients who will undergo this procedure in the future and can guide patient-provider regarding surgical expectations.

Can the Current Thresholds for Synovial Cell Count and Neutrophil Percentage to Diagnose Prosthetic Joint Infection be Applied to Metal-on-Metal Rotating Hinge Total Knee Arthroplasty?

BACKGROUND

Synovial leukocyte count analysis is an important tool in the diagnosis of PJI. However, results can be poor if metallosis is present. The issue of metallosis was established for some rotating hinge knee arthroplasty designs.

METHODS

This was a retrospective single-center analysis that included 108 patients who had a single-design metal-on-metal rotating hinge knee arthroplasty who underwent revision surgery and had prior synovial fluid analysis performed. The diagnostic accuracy of leukocyte count and the percentage of polymorphonuclear neutrophiles (% PMN) were investigated.

RESULTS

Patients who had a PJI had a higher median leukocyte count and % PMN compared to aseptic revisions (7,905/μL (interquartile range (IQR) 2,419 to 37,400) and 85% (IQR 70.3 to 93.8) versus 450 (IQR 167 to 1,215) and 46% (IQR 28.5 to 67.4%), P < .001). The respective areas under the curves were 0.916 (95% confidence interval 0.862 to 0.970) for leukocyte count and 0.821 (95% confidence interval 0.739 to 0.902) for % PMN. We calculated an optimal cut-off value of 1,200 leukocytes/μL (Sensitivity 94.5%/specificity 75.5%) and 63% PMN (Sensitivity 85.5%/specificity 73.6%) to define PJI. Established thresholds were less sensitive, but more specific. The "infection likely" scenario of the European Bone and Joint Infection Society (EBJIS) definition was closest to the calculated thresholds.

CONCLUSION

Currently used thresholds for leukocyte cell count and %PMN to define PJI were less sensitive and specific in the diagnosis of PJI in metal-on-metal RHK knees. Surgeons must consider lower cut-off values when evaluating such implants for PJI.

The Megaendoprosthesis in Revision Arthroplasty - a Cost-revenue Analysis in the aG-DRG System

Megaendoprosthesis offer a viable treatment in complex revision arthroplasty cases with good functional outcome. In the context of a neoplastic indication, the diagnosis-related group (DRG) I95A is usually assigned with a relative weight of 4.906 (2021). In contrast, in revision arthroplasty, the appropriate DRG is assigned, depending on the joint replacement. The additional costs compared to the invoiced DRG are to be compensated by agreeing on hospital-specific individual fees. These complex revision arthroplasties set high technical and operative demands and are mainly performed in specialised departments. We conducted a cost-benefit analysis of the use of the megaendoprosthesis in revision cases in a specialised orthopaedic clinic, as a single centre study. The question we sought to answer was: Is cost recovery possible in the modified German DRG system (aG-DRG)?A retrospective single centre analysis of treatment costs was performed. From 2018 to 2020, 113 patients treated with a megaendoprosthesis reconstruction in a referral centre due to extensive bone loss after aseptic or septic revision of a hip or knee prosthesis were included in the study. Relevant case-related cost drivers of the aG-DRG matrix (including staff and material costs of the operating theatre area and the ward) were taken into account. The actual costs were determined according to the specifications of the calculation manual published by the German institute for the remuneration system in hospitals (InEK). For each case, the contribution margin was calculated by relating the hospital's internal costs to the corresponding cost pool of the aG-DRG matrix.According to the DRG system 2021, 17 different DRGs were used for billing - in 70% based on a patient clinical complexity level (PCCL) ≥ 4. Compared with the InEK calculation, there is a deficit of -2,901 € per case in the examined parameters. The costs of physicians show a shortfall in both the operating theatre and on the ward. Implant costs, which were supposed to be compensated by hospital-specific additional charges, show a hospital-specific shortage of -2,181 €. When analysing the risk factors for cost recovery, only these showed a significant difference.Implantation of the megaendoprosthesis in revision arthroplasty is often the last option to preserve limb function. At present, despite a high degree of specialisation and process optimisation, this treatment cannot be provided cost-effectively even in tertiary care. The politically desired specialised department structure requires sufficient reimbursement for complex cases. The economic outcome of each treatment case is often unpredictable, however the surgeon is confronted with these cases and is expected to treat them. The high standard deviation indicates large differences in the cost/revenue situation of each individual case. Our results show for the first time a realistic cost analysis for megaprosthesis in revision arthroplasty and underline the importance of an adequate hospital-specific charge, individually agreed by the funding units. The calculation should include not only the implant costs, but also the increased staff costs (increased, complex planning effort, quality management, surgery time, etc.).

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.

First-time revision knee arthroplasty using a hinged prosthesis : temporal trends, indications, and risk factors associated with re-revision using data from the National Joint Registry for 3,855 patients

AIMS

The aim of this study was to identify variables associated with time to revision, demographic details associated with revision indication, and type of prosthesis employed, and to describe the survival of hinge knee arthroplasty (HKA) when used for first-time knee revision surgery and factors that were associated with re-revision.

METHODS

Patient demographic details, BMI, American Society of Anesthesiologists (ASA) grade, indication for revision, surgical approach, surgeon grade, implant type (fixed and rotating), time of revision from primary implantation, and re-revision if undertaken were obtained from the National Joint Registry data for England, Wales, Northern Ireland, and the Isle of Man over an 18-year period (2003 to 2021).

RESULTS

There were 3,855 patient episodes analyzed with a median age of 73 years (interquartile range (IQR) 66 to 80), and the majority were female (n = 2,480, 64.3%). The median time to revision from primary knee arthroplasty was 1,219 days (IQR 579 to 2,422). Younger age (p < 0.001), decreasing ASA grade (p < 0.001), and indications for revision of sepsis (p < 0.001), unexplained pain (p < 0.001), non-polyethylene wear (p < 0.001), and malalignment (p < 0.001) were all associated with an earlier time to revision from primary implantation. The median follow-up was 4.56 years (range 0.00 to 17.52), during which there were 410 re-revisions. The overall unadjusted probability of re-revision for all revision HKAs at one, five, and ten years after surgery were 2.7% (95% confidence interval (CI) 2.2 to 3.3), 10.7% (95% CI 9.6 to 11.9), and 16.2% (95% CI 14.5 to 17.9), respectively. Male sex (p < 0.001), younger age (p < 0.001), revision for septic indications (p < 0.001) or implant fracture (p = 0.010), a fixed hinge (p < 0.001), or surgery performed by a non-consultant grade (p = 0.023) were independently associated with an increased risk of re-revision.

CONCLUSION

There were several factors associated with time to first revision. The re-revision rate was 16.2% at ten years; however, the risk factors associated with an increased risk of re-revision could be used to counsel patients regarding their outcome.Cite this article: Bone Joint J 2023;105-B(1):47-55.

A comparison of osteoarticular allografts and allograft-prosthesis composites for reconstruction of the distal femur after resection of a bone tumour in childhood : a retrospective study

AIMS

Osteoarticular reconstruction of the distal femur in childhood has the advantage of preserving the tibial physis. However, due to the small size of the distal femur, matching the host bone with an osteoarticular allograft is challenging. In this study, we compared the outcomes and complications of a resurfaced allograft-prosthesis composite (rAPC) with those of an osteoarticular allograft to reconstruct the distal femur in children.

METHODS

A retrospective analysis of 33 skeletally immature children with a malignant tumour of the distal femur, who underwent resection and reconstruction with a rAPC (n = 15) or osteoarticular allograft (n = 18), was conducted. The median age of the patients was ten years (interquartile range (IQR) 9 to 11) in the osteoarticular allograft group and nine years (IQR 8 to 10) in the rAPC group (p = 0.781). The median follow-up of the patients was seven years (IQR 4 to 8) in the osteoarticular allograft group and six years (IQR 3 to 7) in the rAPC group (p = 0.483). Limb function was evaluated using the Musculoskeletal Tumor Society (MSTS) score.

RESULTS

At final follow-up, the knee was unstable in 9/18 patients (50%) in the osteoarticular allograft group and 2/15 patients (13%) in the rAPC group (p = 0.026). The median range of motion (ROM) of the knee was 117° (IQR 115° to 120°) in the osteoarticular allograft group and 100° (IQR 95° to 105°) in the rAPC group (p < 0.001). The median MSTS score was 25 (IQR 23 to 26) in the osteoarticular allograft group and 28 (IQR 26 to 29) in the rAPC group (p = 0.007). Osteoarthritic change was detected in 11/18 patients (61%) in the osteoarticular allograft group and in 4/15 (26%) patients in the rAPC group (p = 0.048).

CONCLUSION

In our series, a resurfaced allograft-prosthesis composite provided better knee stability and function, with a lower rate of osteoarthritis; an osteoarticular allograft was associated with better knee ROM.Cite this article: Bone Joint J 2022;104-B(10):1174-1179.