Patient-specific chondrolabral contact mechanics in patients with acetabular dysplasia following treatment with peri-acetabular osteotomy

Abstract

PAO was efficacious at medializing cartilage contact and reducing cartilage contact stresses, and therefore may minimize deleterious loading to focal cartilage lesions, subchondral cysts, and cartilage delaminations often observed in the lateral acetabulum of dysplastic hips. However, the excessively prominent, hypertrophied labrum of dysplastic hips remains in contact with the femoral head, which continues to load the labrum following PAO. The clinical ramifications of continued labral loading following PAO are not known. However, it is plausible that failure to reduce the load experienced by the labrum could result in end-stage hip OA following PAO.

A computational investigation of patient factors contributing to contact stress abnormalities in the dysplastic hip joint

“…Dysplastic hips indicated to have developed osteoarthritis following PAO could also be studied with FEA to understand the potential effects of shear stresses on the articular cartilage.4.2 Influence of Gait Loading Pattern on Contact Stress and Patient OutcomesAs detailed above (section 3.1 Influence of Gait Loading Pattern on CalculatedContact Stress and Relationship with Patient-Reported Outcomes), loading the models with the dysplastic gait pattern resulted in calculation of pre-operative maximum contact stresses that were significantly greater than those that were calculated when loading the models with the normal or the arthritic gait pattern. The maximum contact stress values calculated using our DEA methodology were similar in magnitude to those previously reported in DEA and FEA studies of PAO patients[73,96,111] and contact stress values from Tekscan sensors in cadaver hips[77], verifying that our methods produce realistic representations of the contact mechanics of the hip joint.This dysplastic gait pattern in the DEA models of our dysplasia patients prior to PAO resulted in calculation of greatly increased contact stress. This was particularly interesting as this would indicate that the joint stabilization techniques used by hip dysplasia patients during gait may be producing damaging contact stress and contributing to their clinical symptoms.…”

“…In Bergmann's study, kinematic and kinetic measurements were obtained during a variety of activities of daily living in four subjects of ages 51-76 years who received instrumented total hip prostheses for treatment of osteoarthritis. This data set has the most extensive kinematic and kinetic gait data currently available, and the high reliability of instrumented total hip measurements has led to frequent use of this data set in computational modeling studies of the hip [93][94][95][96]. Hence, this gait pattern was believed to be the most logical starting point for use with our models.…”

“…In addition to evaluating the presence of femoral deformities, relationships between contact stress and patient demographics were investigated. Previous PAO studies that have investigated contact mechanics [73,96,111] included subjects of a wide age range. It is unclear how the age of the patient at the time of operation on the biomechanical and clinical outcomes.…”

Editorial Commentary: Hip Arthroscopy in Hip Dysplasia: Just Because You Are Doing It, Should You?

“…In hip arthroscopy while we can reliably remove bone with osteoplasties and repair soft tissues such as the labrum and capsule, without a corrective osteotomy, we will not be changing the shear and high contact forces on the acetabular cartilage in a shallow high acetabular index hip. 2 In this recent study by them, Matsuda et al describe what the surgeons are doing, not how these patients are doing. The group should be congratulated on their achievement of cataloging over 1,053 hips with good data.…”

Effects of sclerotic changes on stress concentration in early‐stage osteonecrosis: A patient‐specific, 3D finite element analysis

“…Using a finite element model (FEM) analysis, it is possible to predict stress distribution in the hip joint in vivo . Recent FEM studies have adopted the concept of Drucker–Prager equivalent stress, which treats bone as a brittle material .…”