Iatrogenic Articular Cartilage Injury in Arthroscopic Hip and Knee Videos and the Potential for Cartilage Cell Death When Simulated in a Bovine Model

Abstract

Purpose: To determine the incidence and characterize the severity of iatrogenic cartilage injuries.

Methods: Technique videos of arthroscopic femoral acetabular impingement procedures and meniscus repairs on VuMedi (n = 85) and Arthroscopy Techniques (n = 45) were reviewed and iatrogenic cartilage injuries were identified and graded (minor, intermediate, and major injury) by 2 independent reviewers. To demonstrate that even minor injuries on a cellular scale result in damage, a bovine osteochondral explant was used to create comparable minor iatrogenic injuries at varied forces that do not disrupt the articular surface (1.5 N, 2.5 N, and 9.8 N). Dead chondrocytes at the site of injury were stained with ethidium homodimer-2 and imaged with an Olympus FV1000 confocal microscope. χ² tests were used for analysis; all results with P < .05 were considered significant.

Results: In total, 130 videos of arthroscopic meniscus and femoral acetabular impingement procedures were analyzed and the incidence of iatrogenic cartilage injury was 73.8%. There were 110 (70.0%) minor, 35 (22.3%) intermediate, and 11 (7.0%) major iatrogenic injuries. All forces tested in the minor injury bovine model resulted in chondrocyte death at the site of contact.

Conclusions: Iatrogenic articular cartilage injuries are common in arthroscopy, occurring in more than 70% of the surgeon-published instructional videos analyzed. At least some chondrocyte death occurs with minor simulated iatrogenic injuries (1.5 N).

Clinical relevance: The high rate of cartilage damage during arthroscopic technique videos likely under-represents the true incidence in clinical practice. Cell death occurs in the bovine minor injury model with minimal contact forces. This suggests iatrogenic cartilage damage during arthroscopy could contribute to clinical outcomes.

Figure 1.

Cartilage Injury Severity. Example of A) minor (deformation of the articular surface without laceration or tear of tissue) B) intermediate (laceration or tear of articular cartilage without visualization of subchondral bone) and C) major (laceration or tear of articular cartilage with subchondral bone visualization) iatrogenic cartilage injuries observed in technique videos.

Figure 2.

Incidence of Observed Iatrogenic Injury in Techinique Videos. Overall, the observable incidence of injuries was high, with minor injuries being the most common. 110 injuries were graded as minor injuries (70.0%), 35 injuries were graded as intermediate injuries (22.3%) and 11 injuries were graded as major injuries (7.0%). Inter-observer reliability was 0.73.

Figure 3.

Iatrogenic Cartilage Injury Results in Cell Death. Bovine femoral condyle explants were injured using a standard arthroscopic trochar loaded with 1.5 N(A), 2.5 N (B), or 9.8 N (C) and translated across the cartilage surface to mimick minor iatrogenic arthroscopic injury. Dead cells were imaged utilizing ethidium homodimer and confocal microscopy. With increasing force applied to a conical arthroscopic trochar, the width of the zone of injury increases in bovine articular explants as demonstrated at 1.5 N (left) 2.5 N (middle) and 9.8 N (right) (p<0.001).

Figure 4.

A) Cell Death Comparison Between Load-Bearing (A) and Non-Loadbearing Cartilage Surfaces. Under conditions described in Figure 3, width of injury was compared between load bearing and non-load bearing aspects of bovine femoral condyles. Again, the width of the zone of injury significantly increased with increasing force (A 1.5N; B 2.5 N; C 9.8N) in both the load-bearing portion of femoral bovine explants and the non-load bearing regions. The zone of injury did not vary in width when comparing load-bearing and non-load bearing regions (p>0.05). B) Zone of Injury Does Not Propagate Over Time. After initial injury and 2 h normal saline incubation, explants were replaced in media at 37 ‘C and cell death was visualized at t=0.5 h, 1 h, 2h, 6 h, and 24 h. At 250 N, the area of zone of injury remained stable over time and did not show changes in width.