# Reduced quadriceps deficit following dry arthroscopy compared to standard fluid arthroscopy at the time of MPFL reconstruction

## TL;DR

Using dry arthroscopy instead of fluid arthroscopy during MPFL reconstruction leads to better quadriceps recovery and fewer post-surgery complications.

## Contribution

This study is the first to compare quadriceps recovery outcomes between dry and fluid arthroscopy during MPFL reconstruction.

## Key findings

- Dry arthroscopy resulted in significantly better quadriceps strength compared to fluid arthroscopy.
- Fluid arthroscopy was associated with higher post-operative effusion rates and reduced knee flexion.
- Dry arthroscopy showed improved limb symmetry index and faster recovery of knee function.

## Abstract

Recurrent patellar dislocations (RPDs) are prevalent, particularly among adolescents. The ‘Menu à la carte’ technique facilitates personalized management of each patient through reconstruction of the medial patellofemoral ligament (MPFL) while simultaneously addressing other anatomical factors that may contribute to instability. Arthroscopy, frequently performed prior to stabilization surgery to identify and treat intra‐articular pathology, carries specific risks. Fluid arthroscopy can increase post‐operative effusion, while dry arthroscopy may expose cartilage to potential damage due to the absence of fluid, increasing friction and thermal effects. Concurrent knee arthroscopy to evaluate and address intra‐articular pathology at the time of MPFL may contribute to post‐operative quadriceps deficits that can significantly impact recovery. Therefore, this study aimed to evaluate and compare quadriceps recovery following either traditional fluid or dry arthroscopy at MPFL reconstruction. The hypothesis was that MPFL reconstruction with fluid arthroscopy would result in more significant quadriceps deficiency, more effusions, and decreased early post‐operative knee flexion compared to the dry arthroscopy group.

This retrospective study analyzed 66 patients who underwent MPFL reconstruction for RPD between February 2020 and February 2024. Exclusion criteria included trochleoplasty, tibial tubercle osteotomy, or missed isokinetic tests beyond 6 months post‐operatively. Patients underwent fluid arthroscopy until September 2021 and dry arthroscopy thereafter. Post‐operative follow‐up at 6 weeks recorded range of motion, patellar apprehension and clinical diagnosis of knee effusion, while isokinetic testing at 4–6 months compared peak torque and muscle strength between the fluid and air arthroscopy groups.

Isokinetic tests revealed a significant deficit in quadriceps strength of the operated knees during MPFL reconstructions performed under fluid compared to those performed dry, both at concentric 60°/s (73.3 ± 33.8 vs. 95.5 ± 39.5 N m/kg; p = 0.02), and at concentric 240°/s (53.6 ± 27.0 vs. 66.5 ± 28.7 N m/kg; p = 0.04) between 4 and 6 months post‐operative. The limb symmetry index (LSI) showed a significant quadriceps strength deficit in the fluid arthroscopy group compared to the dry arthroscopy group, both at concentric 60°/s (63.8 ± 18.0 vs. 75.2 ± 17.2; p = 0.01) and 240°/s (69.6 ± 19.8 vs. 78.5 ± 13.6; p = 0.04). The fluid arthroscopy also demonstrated an increased incidence of post‐operative effusion (47% vs. 19%, p = 0.01) and decreased knee flexion (129.7 ± 13.9° vs 119.3 ± 16.3°, p = 0.01) when compared to the dry arthroscopy group at 6 weeks post‐operative.

This study has demonstrated a significant quadriceps strength deficit in isokinetic tests following fluid arthroscopy compared to dry arthroscopy as well as a higher incidence of effusion and flexion deficit post‐operative. These findings highlight the potential for dry arthroscopy to assess intra‐articular pathology during MPFL reconstruction.

Level III, retrospective, case–control study.