Summary

Iatrogenic articular cartilage injuries are common during arthroscopy; minimal force (1.5N) causes profound superficial cartilage cell death at the site of arthroscopic tool contact with cartilage.

Abstract

Introduction

Arthroscopic procedures are being performed in increasingly constrained anatomic locations in the hip and knee. During these procedures, arthroscopy tools may come into contact with the native cartilage, creating visible indentation or partial-thickness cartilage injuries. To date, no study has assessed the prevalence or severity of iatrogenic cartilage lesions in the knee or hip. Furthermore, the effect of arthroscopic tool contact with articular cartilage has not been described on a cellular level.

Methods

Technique videos of arthroscopic hip procedures and meniscus repairs on VuMedi and Arthroscopy Techniques were reviewed and iatrogenic cartilage injuries were identified and graded by two independent reviewers (minor, intermediate, and major injury). To investigate cellular injury, an arthroscopic trochar was used to create minor iatrogenic injuries in bovine femoral condyle explants at load bearing and non-load bearing sites. Varied masses were used during injury to mimic minor (1.5N), intermediate (2.5N) and major injury (9.8N). The explant was incubated in 0.9% normal saline for 2 hours at 37ºC to simulate a 2-hour arthroscopic procedure. Samples were incubated with 1 ug/mL ethidium homodimer-2 and imaged with an Olympus FV1000 confocal microscope.

Results

112 unique videos of arthroscopic meniscus and hip procedures were identified. The overall incidence of iatrogenic cartilage injury among all technique videos was 74.1% (83/112). The rate of cartilage injury was not statistically different between the knee and hip procedures (p = 0.53). 137 injuries occurred in 112 technique videos. There were 80 (58.4%) minor, 51 (37.5%) intermediate, and 6 (4.4%) major iatrogenic injuries.
The effect of trochar contact with articular cartilage was assessed on load-bearing and non-load bearing surfaces of a bovine knee at three forces (1.5 N, 2.5 N, and 9.8 N). The cartilage was stained with ethidium homodimer-2 to assess cell viability and death, respectively, about at the injury site. The width of injury was not statistically significant between the load-bearing and non-load bearing surfaces. The highest force, (9.8 N) showed increased width of injury which was statistically significant (p=0.01) compared with the smaller forces (1.5 and 2.5 N).

Discussion

The review of surgical technique videos revealed a >70% rate of iatrogenic injury during arthroscopy to articular cartilage. Technique videos are widely utilized as an educational resource, and thus represent a sample of model technique. Therefore, we believe these sources likely under-represent the true clinical rate of iatrogenic injury. Additionally, forces as small as 1.5 N (or 150 g) caused reproducible cell death in an ex-vivo scratch model. At higher forces (9.8 N), the zone of injury increased, which may represent increased contact of the conical shape of the trochar as it sinks into the cartilage, or greater deformation and subsequent shearing force across the extracellular matrix.

Conclusions

Iatrogenic articular cartilage injuries are common in arthroscopy occurring in more than 70% of surgeon-published instructional videos. Chondrocyte death occurs with even with minor simulated iatrogenic injuries. Further prospective studies evaluating the impact of iatrogenic cartilage injuries during arthroscopy are warranted.