What Is the Clinical Efficacy of Combined Semitendinosus Autograft Reconstruction and Scar Tissue Repair for Chronic Irreparable Patellar Tendon Rupture?

Background: Chronic patellar tendon rupture is a rare but serious injury that can lead to significant functional impairment if not treated effectively. Traditional repair methods often result in rerupture because of tendon defects, adhesions, and poor tissue quality. Although tendon graft reconstruction is the first-line treatment, the role of combining the remaining scar tissue with tendon grafting in improving patient-reported outcomes has not been fully explored.

Questions/purposes: (1) What improvements in patient-reported outcomes and radiographic results were observed after reconstruction of chronic patellar tendon ruptures with semitendinosus autograft combined with scar tissue repair? (2) What ROM was achieved after recovery, and were patients free from extensor lag? (3) What surgical complications were associated with this technique?

Methods: This retrospective case-series study included 47 patients with chronic patellar tendon rupture treated from January 2010 to December 2023 diagnosed by clinical assessment, MR imaging, and surgical exploration during the procedure. Among the 47 patients, 23 patients met the following inclusion criteria: (1) radiographic patella alta (Caton-Deschamps Index [CDI] > 1.3 or modified Insall-Salvati Index [ISI] > 2) with MRI confirmation of patellar tendon rupture and (2) treatment with semitendinosus autografts reconstruction and scar tissue repair. Two patients were lost to follow-up before the minimum study follow-up time of 1 year, and for patients with bilateral rupture, we included the more affected side, leaving 21 of 47 patients with 21 knees ultimately included in the final analysis. For each included patient, we collected preoperative baseline and final follow-up data, which included patient-reported outcome measures (PROMs) such as International Knee Documentation Committee (IKDC) score and Lysholm score, knee ROM, extensor lag, patellar height assessed by CDI and ISI, and any surgical complications. All patients had at least 12 months of follow-up (median [range] 65 months [12 to 161]). Follow-up data were obtained from clinical visits, phone interviews, and medical records.

Results: Patient-reported outcomes demonstrated improvements, with the IKDC score increasing from a mean ± SD 46 ± 6 preoperatively to 92 ± 5 postoperatively (mean difference -46 [95% confidence interval (CI) -49 to -43]; p < 0.01). Radiographic evaluation confirmed normal restoration of patellar height, with the CDI improving from a mean ± SD 1.9 ± 0.3 to 1.1 ± 0.1 and the modified ISI from 2.4 ± 0.3 to 1.5 ± 0.2. Postoperative knee ROM improved from 100° ± 31° to 140° ± 2° (mean difference -40° [95% CI -54° to -25°]; p < 0.01). Extensor lag resolved in 16 of 21 patients (21 of 21 preoperatively versus 5 of 21 postoperatively), with a mean deficit of 1° ± 2°, representing a mean improvement of 33° (95% CI 22° to 43°; p < 0.01). One of 21 patients was rehospitalized because of poor postoperative incision healing. No other major complications occurred.

Conclusion: In this study, we demonstrated that reconstruction with semitendinosus autografts combined with scar tissue repair provides significant improvements in patient-reported outcomes and functional measures for patients with chronic patellar tendon rupture. The IKDC score, ROM, and extensor lag all showed substantial improvement postoperatively. While our findings were promising, the lack of a comparator group limited our ability to draw definitive conclusions about the role of scar tissue in tendon remodeling. Future studies with a larger sample size and a comparator group could provide more insights into these aspects, including the potential impact of scar tissue on tendon healing through histopathologic evaluation.

Level of evidence: Level IV, therapeutic study.