Are Complications Associated With the Repiphysis® Expandable Distal Femoral Prosthesis Acceptable for Its Continued Use?

Abstract

Background Reconstruction of the distal femur after resection for malignant bone tumors in skeletally immature children is challenging. The use of megaprostheses has become increasingly popular in this patient group since the introduction of custom-made, expandable devices that do not require surgery for lengthening, such as the Repiphysis 1 Limb Salvage System. Early reports on the device were positive but more recently, a high complication rate and associated bone loss have been reported. Questions/purposes We asked: (1) what are the clinical outcomes using the Musculoskeletal Tumor Society (MSTS) scoring system after 5-year minimum followup in patients treated with this prosthesis at one center; (2) what are the problems and complications associated with the lengthening procedures of this implant; and (3) what are the specific concerns associated with revision of this implant? Methods At our institute, between 2002 and 2007, the Repiphysis 1 expandable prosthesis was implanted in 15 children (mean age, 8 years; range, 6-11 years) after distal femoral resection for malignant bone tumors. During this time, the general indication for use of this implant was resection of the distal femur for localized malignant bone tumors in pediatric patients. Alternative techniques used for this indication were modular prosthetic reconstruction, massive (osteoarticular or intercalary) allograft reconstruction, or rotationplasty. Age and tumor extension were the main factors to decide on the surgical indication. Of the 15 patients who had this prosthesis implanted during reconstruction surgery, five died with the implant in situ or underwent amputation before 5 years followup and the remaining 10 were evaluated at a minimum of 5 years (mean, 104 months; range, 78-140 months). No patients were lost to followup. These 10 patients were long-term survivors and underwent the lengthening program. They were included in our study analysis. The first seven lengthening procedures were attempted in an outpatient setting; however, owing to pain and burning sensations experienced by the patients, the procedures failed to achieve the desired lengthening. Therefore, other procedures were performed with the patients under general anesthesia. We reviewed clinical data at index surgery for all 15 patients. We further analyzed the lengthening procedures, implant survival, radiographic and functional results, for the 10 long-term survivors. Functional results were assessed according to the MSTS scoring system.

Limb Salvage Using Non‐hinged Endoprosthesis and Staged Correction of Leg‐length Discrepancy for Children with Distal Femoral Malignant Tumors

“…A high complication rate of the extendable prosthesis has been highlighted in some studies. An average 50% revision rate is reported for non‐invasive expandable endoprostheses.…”

“…To address LLD following limb salvage surgery, expandable prostheses have been developed. However, besides the high complication rate, up to 50% of patients who have expandable prosthesis reconstruction do not undergo further lengthening procedures due to oncological failures or overestimation of expected LLD. In addition, small degrees of LLD up to 2.2 cm can be well compensated by mechanism of pelvic obliquity, and the children usually have a normal gait.…”

Review of Osteosarcoma and Current Management

“…Some require minimal surgery for mechanical expansion, while others rely on an electromagnet for noninvasive lengthening. The noninvasive implants have the advantage of avoiding further surgery, but the first generation has had an intolerable failure rate [109, 110]. Second-generation noninvasive implants have only been available for a short time, but may be more stable.…”

Advances in the management of osteosarcoma

“…Various non-invasive lengthening mechanisms are now available, including incorporated engines or magnetic devices 30 . However, these are still associated with frequent complications and needs for revisions 31– 33 . Several papers emphasize that further technical advances are direly needed: in one series, 10 patients experienced 37 implant-related complications 31 , and in another, 42% of 38 patients experienced complications, including 10 prosthesis revisions and two amputations 34 .…”

“…Several papers emphasize that further technical advances are direly needed: in one series, 10 patients experienced 37 implant-related complications 31 , and in another, 42% of 38 patients experienced complications, including 10 prosthesis revisions and two amputations 34 . A third reported an average 2.5 revisions for complications in 71 patients 32 ; a fourth even questioned whether complications associated with a particular, rather popular, expandable prosthesis were acceptable for its continued use 33 . Given that such devices are obviously still immature, one might look back to the bygone age of rotationplasties with (never expected) nostalgia.…”