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Impact of Cartilage Lesions

The spectrum of pathology includes a gradation in the severity of cartilage damage beginning with simple delamination of a small area and ending with complete degeneration of the articular surfaces, i.e., osteoarthritis.

Although the glenohumeral joint surface geometry historically has been considered less of a stabilizing factor as a result of the smaller surface area of the glenoid in comparison with the humeral head and the apparent shallowness of the glenoid, technology has now given us a new perspective.

Classically, most studies of the joint have analyzed congruency with radiographs, thus underestimating the degree of congruity afforded by the articular cartilage because only the bony surfaces were visualized and assesse. If only the subchondral bone is analyzed, there appears to be less conformity within the joint. With the addition of the articular cartilage, the effective congruence of the joint is much greater.

As an example, Kelkar et al.It analyzed a group of glenohumeral cadaveric joints. In their analysis, the average radii of the humeral head and glenoid articular surfaces were 25.5 and 27.2 mm, respectively. The average difference between the two radii was 1.7 ± 1.5 mm. When the same technique was employed to analyze the subchondral bone, the radii of curvature of the humeral heads and glenoids were 25.2 and 33.4 mm, respectively.

These findings lend more importance to the articular cartilage, or more specifically the preservation of this tissue. It appears that the articular cartilage of the glenohumeral joint is a factor in the maintenance of stability in the joint. Given the inherently unstable nature of the joint with its small surface area, it is paramount to save as much cartilage as possible in order to preserve normal joint function.

Another consideration is the impact of associated coexistent disease processes in the shoulder. More importantly, focal articular lesions are often found incidentally at the time of arthroscopic evaluation of the joint for other presumptive diagnoses. This problem has been seen less frequently as a result of the improvements made in prospective diagnosis with the use of MRI techniques, particularly those employing gadolinium-enhanced arthrograms.

Several studies allude to the coexistence of other disease processes with cartilage lesions, however, especially more advanced lesions seen with osteoarthritis . In their study, Feeney and colleagues assessed 33 cadaveric shoulder joints and documented the incidence of rotator cuff tearing and cartilage lesions . Articular cartilage degeneration was almost twice as frequent in the group with rotator cuff tears as in those without tearing .

Another study revealed that in a series of 52 patients undergoing surgery for subacromial impingement syndrome, humeral cartilage lesions were found in 29%, of which four lesions were subtle and eleven were marked (9). In the glenoid, 15% were found to have lesions with three subtle and five marked. In essence, patients with clear surgical indications for impingement surgery may have coexistent cartilage lesions in up to one third of instances. This consideration should be taken into account at the time of preoperative discussion with the patient, as other procedures may be essential for complete treatment.

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