Cartilage atrophy in the knees of patients after seven weeks of partial load bearing

Abstract

Objective. It is currently unknown whether human cartilage properties change during short periods of partial load bearing. We used a post-ankle fracture model to explore whether changes in cartilage morphology occur in the knee under conditions of partial load bearing.Methods. The knees of 20 patients with Weber type B and type C fractures were examined using magnetic resonance imaging. The first scan was obtained shortly (mean ؎ SD 3.2 ؎ 3.0 days) after the injury, and a second scan was obtained 7 weeks later (mean ؎ SD 50.7 ؎ 5.5 days). The morphology (mean and maximum thickness, volume, and surface area) of the patellar, tibial, and femoral cartilage was determined from coronal and axial magnetic resonance images (fat-suppressed gradient-echo).Results. Between week 0 and week 7, the crosssectional area of the quadriceps muscle was reduced by 11% (P< 0.001). Changes in the mean (؎SD) cartilage thickness ranged from ؊2.9 ؎ 3.2% in the patella to ؊6.6 ؎ 4.9% in the medial tibia. No significant change in cartilage morphology of the contralateral knee was observed. Conclusion.Results of this study demonstrate that in a post-ankle fracture model of partial load bearing, cartilage morphology in all knee compartments is subject to significant change. Changes in the femorotibial joint exceeded those in the patella, whereas no change was observed in the contralateral knee. These findings raise the question of whether cartilage is mechanically less competent and particularly vulnerable after states of partial or complete immobilization.Quantitative magnetic resonance imaging (MRI) is a novel, but established, technique for studying cartilage morphology under physiologic and pathophysiologic conditions (1-5). Recent studies have shown that cartilage thinning occurs during aging (4), in osteoarthritis (OA) (2,6,7), after partial meniscectomy (8), and after spinal cord injury (3,9). Results from animal models have shown that cartilage morphology, composition, and mechanical properties are subject to change during immobilization (10). However, it is as yet unknown whether changes occur in human cartilage during short periods of immobilization or partial load bearing. Such information is important in the postoperative management of OA and in the context of space travel (i.e., when astronauts return to normal gravity conditions after long-term space flight). The relevant question here is whether or not cartilage properties change under conditions of partial load bearing, and, supposing that such changes do occur, whether cartilage is vulnerable to injury when normal load-bearing conditions are reestablished.In this study, we made use of the fact that patients who have undergone operative treatments of ankle fractures are subject to a 7-week period of partial load bearing. We explored the extent to which the cartilage morphology of the ipsilateral knee changed during the postoperative period in relation to the loss of cross-sectional area of the quadriceps muscle.

A Novel Experimental Knee-Pain Model Affects Perceived Pain and Movement Biomechanics

“…These biomechanical alterations would also likely affect articular cartilage health, as articular cartilage health depends upon appropriate knee jointloading patterns. 14,37 An unloading strategy might also result in chronic bilateral strength asymmetry 38 because this potential unloading strategy implies altered loading characteristics for the uninvolved lower extremity. For example, if impulse due to vertical GRF is decreased for the involved lower extremity, the same impulse must increase for the uninvolved lower extremity to adequately support the center of mass during walking.…”

The Feasibility of a 3-Month Active Rehabilitation Program for Patients With Knee Full-Thickness Articular Cartilage Lesions: The Oslo Cartilage Active Rehabilitation and Education Study

“…47,60 These in vitro findings are consistent with results of animal studies and investigations in humans. 20,35,64,67 The absence of mechanical stimulation has been shown to lead to a decrease in cartilage thickness, leading to some process of cartilage atrophy. 35,64,67 However, it is still unclear whether and how these findings can be directly implemented in the conservative management of patients with articular cartilage lesions, particularly full-thickness articular cartilage lesions.…”

Current Concepts for Rehabilitation and Return to Sport After Knee Articular Cartilage Repair in the Athlete

“…The current concepts of rehabilitation following cartilage repair in the athlete are based on a combination of basic science data, the surgical techniques currently available, empirical information, and a limited number of clinical studies. 5,37,39,45,48,52,62,69,71,72,74,76,92,107,136,147,154,155,190,191 Due to the complex nature of cartilage repair and variable defect characteristics and comorbidities, an individualized rehabilitation approach should be used for every athlete following articular cartilage restoration (TABLE 1). The progression through the rehabilitation process is determined by the biology of the repair technique, characteristics of the cartilage injury, clinical symptoms, radiographic findings, and the athlete's sport-specific demand.…”

“…7,71,92 In the early postoperative phase, the challenge is to construct an individualized rehabilitation program that provides appropriate stimulation, while avoiding mechanical loading that may be detrimental to the repair tissue. Due to the differences introduced by different cartilage repair techniques, lesion characteristics, and concomitant procedures, the initial limit and progression of weight-bearing activities should be individually determined by the surgical and rehabilitation teams for each athlete.…”