Articular cartilage changes in patients with osteoarthritis after osteotomy.

BACKGROUND: High tibial osteotomy (HTO) is a method used to treat medial compartmental osteoarthritis in the knee. The realignment of the knee changes the loading patterns within the joint and may allow for regeneration of articular cartilage. Magnetic resonance imaging methods can be used to assess the quality of the regenerated cartilage. HYPOTHESIS: Altering mechanical alignment through HTO will have predictable effects on articular cartilage, allowing cartilage preservation and possible regeneration. Quality of regenerated cartilage will be inferior to normal articular cartilage. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Ten patients undergoing medial opening wedge HTO were evaluated using dGEMRIC methods (ie, delayed gadolinium-enhanced magnetic resonance imaging of cartilage) preoperatively and at 6 months, 1 year, and 2 years after HTO. Magnetic resonance images were evaluated by hand segmentation, and T1(Gd) relaxation times reflective of glycosaminoglycan content were determined for these regions of interest using magnetic resonance imaging analysis software. RESULTS: The lateral compartment displayed higher T1(Gd) values than the medial compartment at baseline. Initially, a decrease in T1(Gd) values on the medial side were observed for all patients at 6 months and remained reduced for all but 2 participants at 1 year and 2 years after HTO. However, on the medial side after 6 months, the rate of change for T1(Gd) values shifted from being negative (-9.6 milliseconds per month) to being positive (1.7 milliseconds per month). A positive change in the T1(Gd) of the medial tibial plateau was responsible for the positive overall change in the medial compartment. There was no significant difference in the rate of change on the lateral side (P = .141), with the average over the 2-year period being a decrease of 2.28 milliseconds per month. CONCLUSION: Medial opening wedge HTO provides subjective improvements in pain and quality of life, but the potential benefit of allowing articular cartilage preservation and possible regeneration is not well established. Results showed that after a nonweightbearing period, the rate of change in the medial compartment changes from negative to positive, indicating the potential for articular cartilage recovery secondary to an improved mechanical environment.

Gait dynamics on an inclined walkway.

OBJECTIVE: This paper documents research that quantifies and describes the biomechanics of normal gait on inclined surfaces. DESIGN: Experimental, investigative. BACKGROUND: It is necessary to walk on inclined surfaces to negotiate the natural and built environments. Little research has been conducted on the biomechanics of normal gait on inclined surfaces. METHODS: The gait of 11 healthy male volunteers was measured using a Vicon system 370 on an inclinable walkway. Gait was measured at 0 degrees , 5 degrees , 8 degrees and 10 degrees of incline. Passive optical markers were placed on each subject and they walked at a self-selected speed up and down the walkway. Ground reaction forces and EMG were measured. Gait data were analysed in Vicon Clinical Manager. RESULTS: Changes in the dynamics of the lower limbs with respect to incline angles are described. Between subject and between condition differences in biomechanical parameters were significant. Hip flexion increased at heel strike with inclines from -10 degrees to +10 degrees . Knee flexion and ankle dorsiflexion at heel strike increased with increasing angle walking up, but not down. Changes in joint moments and powers due to change in the angle of incline or direction of walking were observed. CONCLUSIONS: The mechanisms by which the body enables walking up and downhill, specifically raising and lowering the centre of mass, and preventing slipping, can be seen in the alteration in the dynamics of the lower limbs. Increases in range of motion and muscle strength requirements need to be considered in the design of lower limb prostheses and in orthopaedic and neurological rehabilitation. RELEVANCE: Gait, prosthetics, rehabilitation, balance and falls.