Antirotation pins improve stability of the compress limb salvage implant: a biomechanical study

Long-term Results of Intercalary Endoprosthetic Short Segment Fixation Following Extended Diaphysectomy

Intercalary endoprosthetic reconstruction following diaphyseal resection of osseous tumors offers functional advantages through preservation of native joints adjacent to the resected defect. Use of such implants is restricted by the amount of bone available for stem fixation adjacent to the defect. This study aimed to determine whether short osseous segment fixation with acceptable outcomes and complication rate can be reliably achieved with a customized intercalary endoprosthesis following extended diaphysectomy. A retrospective review of prospectively collected data was performed on 6 patients receiving customized anchor plugs for short segment fixation with a double compressive osseointegration intercalary implant to reconstruct segmental defects. Five of the implants were augmented with cement to support fixation in metaphyseal bone. Patient age at surgery ranged from 12 to 86 years. At mean follow-up of 39 months, mean Musculoskeletal Tumor Society functional score was 26.3, with 5 of 6 patients achieving scores of 27 or greater. Stable fixation was achieved in all patients, with the shortest segment of bone 3.7 cm in length. Three mechanical implant failures requiring revision surgery occurred. No patient required revision of the entire implant, secondary adjacent joint replacement, or secondary amputation. No patient exhibited aseptic loosening, and no case was complicated by infection. Excellent functional outcomes were seen with follow-up out to 9 years. This suggests that cement-augmented double compressive osseointegration intercalary endoprosthetic reconstruction can extend the benefits of intercalary replacement to many patients who otherwise might require adjacent joint or physeal sacrifice. However, patients should be counseled on the high risk of implant failure with subsequent need for revision surgery. [Orthopedics. 2017; 40(6):e964-e970.].

Long-term outcomes of cement in cement technique for revision endoprosthesis surgery

BACKGROUND AND OBJECTIVE

Cemented endoprosthetic reconstruction after resection of primary bone sarcomas has been a standard-of-care option for decades. With increased patient survival, the incidence of failed endoprostheses requiring revision surgery has increased. Revision of cemented endoprotheses by cementing into the existing cement mantle (CiC) is technically demanding.

METHODS

This is a retrospective review of our endoprosthesis database of 512 consecutive cemented endoprosthetic reconstructions performed for oncologic diagnoses between 1980 and 2014. A total of 54 implants (mean patient age 32 years, range 13-81) were revised with a CiC technique. Outcomes evaluated were prosthesis survival, revision surgery categorized according to the Henderson Failure Mode Classification, complications, and functional scores.

RESULTS

Fifteen-year Kaplan-Meier survival rate was 34% for initial revision and 39% for subsequent revision implants. Mean revised Musculoskeletal Tumor Society (MSTS) Score was 27 at latest follow-up. Infection rate was 2%, 9%, and 13% for primary endoprostheses, initial revisions, and subsequent revisions, respectively. Limb salvage rate was 87%.

CONCLUSIONS

At long-term follow up, endoprostheses revised with the CiC technique showed consistent 15-year survival from initial (34%) to subsequent (39%) revision. Despite a relatively high failure rate, these results are encouraging and demonstrate that this is a conservative, repeatable technique.

What Factors Are Associated With Failure of Compressive Osseointegration Fixation?

BACKGROUND

Compressive osseointegration is as an alternative to traditional intramedullary fixation. Two- to 10-year survivorship and modes of failure have been reported; however, as a result of relatively small numbers, these studies are limited in their ability to identify risk factors for failure.

QUESTIONS/PURPOSES

(1) What is survivorship free from aseptic mechanical and survivorship free from overall failure of compressive osseointegration fixation? (2) What patient factors (age, sex, body mass index [BMI], anatomic location of reconstruction, indication for reconstruction, radiation, chemotherapy) are associated with increased risk of failure?

METHODS

Between 2006 and 2014, surgeons at one center treated 116 patients with 137 Compress^® implants for lower extremity oncologic reconstructions, revision arthroplasty, and fracture nonunion or malunion. One hundred sixteen implants were available for review with a minimum of 2-year followup (mean, 4 years; range, 2-9 years). Kaplan-Meier survival plots were produced to examine survivorship and Cox regression modeling was used to generate hazard ratios (HRs) for potential risk factors for failure. Patient factors (age, sex, BMI, anatomic location of reconstruction, indication for reconstruction, radiation, chemotherapy) were obtained from chart review and an institutional database.

RESULTS

Survivorship free from aseptic mechanical failure was 95% (95% confidence interval [CI], 91%-99%) at 18 months and 93% (95% CI, 86%-99%) at 4 years. Survivorship free from overall failure was 82% (95% CI, 75%-89%) at 18 months and 75% (95% CI, 66%-84%) at 4 years. Risk of overall failure was increased with reconstruction of the proximal tibia (HR, 4.42; 95% CI 0.98-19.9) and distal femur (HR, 1.74; 95% CI, 0.50-6.09) compared to the proximal femur (HR, 1; referent; p = 0.049). Risk of aseptic mechanical failure was increased with reconstruction of the proximal tibia (HR, 1; referent) and distal femur (HR, 0.37; 95% CI, 0.08-1.77) compared with the proximal femur (HR, 0, p = 0.048). Radiation was associated with increased risk of overall failure (HR, 3.85; 95% CI, 1.84-8.02; p < 0.003), but not aseptic mechanical failure. Age, sex, BMI, chemotherapy, and surgical indication were not associated with increased risk of aseptic or overall failure.

CONCLUSIONS

This study questions the use of age as a contraindication for the use of this technology and suggests this technology may be considered in proximal femoral reconstruction and for patients with indications other than primary oncologic reconstructions. Future research should establish long-term survivorship data to compare this approach with conventional intramedullary stems and to evaluate the potential benefits of preventing stress shielding and preserving bone stock in revision situations.

LEVEL OF EVIDENCE

Level III, therapeutic study.