A novel tool for predicting the survival of endoprosthesis used for reconstruction of the knee following tumor resection: a retrospective cohort study

Background Prosthesis-related complications, after knee reconstruction with endoprosthesis during operation for tumors around the knee, remain an unresolved problem which necessitate a revision or even an amputational surgery. The purpose of the current study was to identify significant risk factors associated with implant failure, and establish a novel model to predict survival of the prosthesis in patients operated with endoprostheses for tumor around knee. Methods We retrospectively reviewed the clinical database of our institution for patients who underwent knee reconstruction due to tumors. A total of 203 patients were included, including 123 males (60.6%) and 80 (39.4%) females, ranging in age from 14 to 77 years (mean: 34.3 ± 17.3 years). The cohort was randomly divided into training (n = 156) and validation (n = 47) samples. Univariable COX analysis was used for initially identifying potential independent predictors of prosthesis survival with the training group (p < 0.150). Multivariate COX proportional hazard model was selected to identify final significant prognostic factors. Using these significant predictors, a graphic nomogram, and an online dynamic nomogram were generated for predicting the prosthetic survival. C-index and calibration curve were used for evaluate the discrimination ability and accuracy of the novel model, both in the training and validation groups. Results The 1-, 5-, and 10-year prosthetic survival rates were 94.0, 90.8, and 83.0% in training sample, and 96.7, 85.8, and 76.9% in validation sample, respectively. Anatomic sites, length of resection and length of prosthetic stem were independently associated with the prosthetic failure according to multivariate COX regression model (p<0.05). Using these three significant predictors, a graphical nomogram and an online dynamic nomogram model were generated. The C-indexes in training and validation groups were 0.717 and 0.726 respectively, demonstrating favourable discrimination ability of the novel model. And the calibration curve at each time point showed favorable consistency between the predicted and actual survival rates in training and validation samples. Conclusions The length of resection, anatomical location of tumor, and length of prosthetic stem were significantly associated with prosthetic survival in patients operated for tumor around knee. A user-friendly novel online model model, with favorable discrimination ability and accuracy, was generated to help surgeons predict the survival of the prosthesis.

Weightbearing Protocols After Posterolateral Corner Reconstruction: A Systematic Review

Background: Multiligamentous knee injuries with a posterolateral corner injury represent a devastating insult to the knee. Purpose: To evaluate multiligamentous knee reconstruction rehabilitation programs and recommend a rehabilitation program based on a review of published outcomes studies. Study Design: Systematic review; Level of evidence, 4. Methods: A MEDLINE (PubMed), OVID, and Embase database search was conducted using the terms “posterolateral corner” and “rehabilitation.” All articles obtained were examined to confirm their rehabilitation programs for multiligamentous knee injuries. These injuries included a posterolateral corner injury plus an isolated anterior or posterior cruciate ligament injury or a combined cruciate injury. Results: Ten publications representing 245 patients with multiligamentous knee reconstruction were analyzed. Rehabilitation protocols were divided by weightbearing (WB) status: in 2 studies, patients were non-WB until postoperative 4 weeks (delayed WB; n = 61); 5 studies permitted progressive WB until postoperative 6 weeks (progressive WB; n = 123); and 3 studies allowed WB immediately after surgery (immediate WB; n = 61). No significant difference in outcome scores among the 3 WB groups was found. Arthrofibrosis requiring manipulation under anesthesia was the most common complication (11%) in the delayed WB group, followed by the immediate WB group (3%) and the progressive WB group (0%; P < .01). Overall complication rates were highest in the delayed WB group (44%), followed by the immediate and progressive WB groups (25% and 3%, respectively; P < .00001). The delayed WB group was permitted to return to sport at a mean of 10.5 months from the index procedure; the progressive WB group, at 6.0 months; and the immediate WB group, at 9.0 months ( P < .05). Conclusion: This review revealed no significant difference in outcome scores when comparing immediate, progressive, and delayed WB protocols. Time to permitted return to sport was not significantly different among the groups, but there existed a trend toward earlier return in the progressive WB group. Patients in the delayed and immediate WB groups experienced a higher overall complication rate. Progressive WB postoperative protocols may decrease the risk of complications without compromising outcomes; however, more research is needed to identify the optimal postoperative rehabilitation protocol, given the significant data heterogeneity currently available in the literature.