Summary

Impact of Biological Augmentation on Patellar Height and Re-Rupture Rates in Acute Patellar Tendon Repair

Abstract

Introduction

Patellar tendon ruptures (PTR) are infrequent but disabling injuries. Surgical treatment is standard, involving isolated repair or augmented techniques. Biomechanical studies suggest better outcomes with augmentation, but consensus on the best technique is lacking, as is clinical evidence comparing them. Patellar height (PH) and the re-rupture rate are used to determine the success of the intervention.

Objectives: The primary objective was to determine differences in PH using the Insall-Salvati index between two groups of acute PTR patients: those treated with isolated repair (IR) and those with added biological augmentation (BA). Secondary objectives included comparing re-rupture rates and other complications between the groups.

Methods

A retrospective review of all acute PTR patients surgically treated at our center between 2016 and 2023, with over 12 months of follow-up. Exclusions included patients with ruptures over 42 days old, those associated with total knee replacement, and those with fractures requiring osteosynthesis. Patient and rupture characteristics, surgical technique, and complications were recorded. PH via the Insall-Salvati index was independently measured on lateral knee X-rays taken the day after surgery and at 4 months by three orthopedic knee surgeons. An independent, blinded evaluator analyzed the measurements, determining the average PH and intraclass correlation coefficient (ICC). Patients with patellar tendon re-rupture were excluded from radiological analysis. Primary outcome was PH difference between groups the day after surgery and at 4 months. Secondary outcomes included re-rupture rate, infection rate, need for re-intervention due to knee stiffness, and extensor mechanism lag > 5º at 12 months.

Results

A non-concurrent cohort study identified 36 acute PTR surgeries. Of these, 93.94% were male, with a mean age of 44.4 years and an average BMI of 28.4. IR surgery (end-to-end, through transosseous tunnels or anchors, depending on the location of the PTR) was performed in 20 patients (55.5%), and repair + BA with autograft or allograft was performed in 16 patients. Demographics were comparable between groups. A significant association was found between surgery type and patellar tendon re-rupture: 5 out of 20 (25%) of IR experienced re-rupture, while none occurred in the BA group (p = 0.033). No significant differences were observed for other complications, including arthrofibrosis requiring fibroarthrolysis (21% vs. 11.1%; p = 0.41), extension lag >5° (26.3% vs. 11.1%; p = 0.23), or infection (0% vs. 5.6%; p = 0.29). Excluding 5 IR failures, the average Insall-Salvati index the day after surgery and at 4 months was 1.15 and 1.21 for the IR group, and 0.97 and 1.07 for the BA group. A significant difference in the Insall-Salvati index was noted between groups both postoperatively (p < 0.0001) and at 4 months (p = 0.0002). ICC showed excellent agreement among observers.

Conclusions

In this cohort of acute PTR, repair with BA showed better PH in the immediate postoperative period and at 4 months, along with a lower re-rupture rate, without being associated with higher complication rates compared to IR.