Paper presentation noted that combined pathology is more deleterious
Cartilage lesions in patients with symptomatic, pre-osteoarthritic diseases are very common, according to Cecilia Pascual-Garrido, MD, who presented results from Paper 899, “Are there Disease-Specific Articular Cartilage Wear Patterns in Various Pre-arthritic Hip Disorders?” during the AAOS 2018 Annual Meeting.

Dr. Pascual-Garrido also noted that the literature on patterns of articular cartilage damage in pre-arthritic hip disease is limited, with most data being derived from single center, retrospective studies of relatively small patient cohorts.

“We attempted to identify a pattern of cartilage damage in the pre-arthritic hip; patients with hip dysplasia, hip impingement, and patients with combined pathology,” she explained.

“We also wanted to see if the morphology of the hip determines the pattern of cartilage damage inside the hip, as well as examine the relationship to other demographic data, such as patient age, sex, body mass index (BMI), and chronicity of pain,” she added.

Trends in cartilage wear
Researchers in the ANCHOR study group conducted a prospective, multicenter, longitudinal cohort study of 1,358 patients (1,358 hips) who underwent surgery for the treatment of acetabular dysplasia and/or femoroacetabular impingement (FAI) between January 2009 and November 2016, and were assessed arthroscopically for articular wear. Patients were excluded if they had previous ipsilateral surgery, sequelae of childhood disease, or associated neurological disorders. Mean patient age at the time of surgery was 30.5 years (range: 8 to 68 years); there were 944 females (70 percent) and 406 males (30 percent). The average BMI was 25 (range: 17 to 53).

Dr. Pascual-Garrido and her colleagues observed articular cartilage damage in 1,213 hips (90 percent). Compared to younger patients, patients older than 20 years had significantly more cartilage wear at the acetabulum (99 percent vs. 83 percent) and the femoral head (11 percent vs. 2 percent). Cartilage lesions in the acetabulum were significantly more likely in patients with a femoral head-neck deformity.

They found that the anterior and superolateral areas of the peripheral aspect of the acetabulum were most commonly affected across all subgroups (Fig. 1).

They further noted disease-specific patterns according to hip morphology: Patients with FAI or developmental dysplasia of the hip (DDH) with associated femoral-head neck deformity (higher alpha angle) presented not only higher wear in the anterior and superolateral aspect of the acetabulum, but also had statistically higher wear in the posterior aspect of the acetabulum. In the femoral head, DDH with or without cam lesions presented significantly more wear in the posteromedial aspect.

“We found that a femoral head-neck deformity was the most deleterious to the hip articular cartilage,” said Dr. Pascual-Garrido. Contrary patients with FAI pincer had the least amount of wear. “The other interesting point to note is that patients with combined pathology—DDH (instability) and FAI (impingement)—had more cartilage damage compared to those with a singular pathology. Essentially, hip morphology defines cartilage damage. These findings allow us to have a better understanding of the effect of hip morphology on cartilage degeneration and development of osteoarthritis. Understanding the pattern of wear can be used as a clinical indicator of the underline pathology of the patient.”

In addition, higher BMI, older age, and chronicity of pain were all associated with higher cartilage wear.

Dr. Pascual-Garrido noted that patients with pincer impingement were the oldest and had the highest BMI, yet they did not show very high cartilage wear, suggesting that hip morphology has a dominant role in the degenerative cascade beyond age and BMI.

Treat early
“It’s better to treat these diseases early on instead of waiting too long,” Dr. Pascual-Garrido said. “And when a patient has both pathologies, they have a greater likelihood of cartilage damage, so as clinicians it makes sense to be a bit more aggressive in terms of treatment before the cartilage starts to break down.

Now, when we treat our patients affected by combined pathologies, we concomitantly treat the femoral head-neck deformity with an osteochondroplasty,” Dr. Pascual-Garrido continued.

In those patients with hip dysplasia and associated femoral head-neck deformity, we intervene with a PAO [periacetabular osteotomy] commonly followed by a femoral head-neck osteochondroplasty. We believe that by correcting the femoral-head neck deformity we are reducing the chances of long-term cartilage failure.”

Dr. Pascual-Garrido’s coauthors are George A. Grammatopoulos, MRCS; Perajit Eamsobhana, MD; Jeffrey J. Nepple, MD; Paul E. Beaule, MD; ANCHOR Study Group; and John C. Clohisy, MD.

Peter Pollack is the electronic content specialist for AAOS Now. He can be reached at ppollack@aaos.org.