A comparison of the spectrum of intra-articular lesions in acute and chronic anterior shoulder instability.

PURPOSE: The purpose of the study was to compare the incidence of secondary intra-articular shoulder lesions in patients with acute and chronic anterior shoulder instability. The occurrence of glenoid shape alterations (inverted pear glenoid) in recurrent instability was especially examined.
METHODS: Data for all arthroscopically ascertained intra-articular shoulder lesions in a series of 127 patients with acute and chronic traumatic anterior instability were recorded.
RESULTS: Hemarthrosis was evident in all patients with acute dislocation and in 7 patients with chronic laxity who underwent surgery shortly after a dislocation episode. In both groups the presence of a chondral or osteochondral Hill-Sachs lesion was noted in 112 patients (88.1%), a Bankart lesion was noted in 106 patients (83.46%), an anterior labroligamentous periosteal sleeve avulsion (ALPSA) lesion was noted in 13 patients (10.23%), a SLAP lesion was noted in 26 patients (20.47%), a humeral avulsion of the glenohumeral ligament (HAGL) lesion was noted in 2 acutely dislocated shoulders (1.57%), and capsular laxity was noted in 33 patients (25.98%). All ALPSA lesions were noted in patients with chronic instability (P = .044), and both HAGL lesions were found in patients with acute dislocations (P = .002). In patients with acute dislocations the incidence of Bankart lesions was 78.2% (18/23), whereas in chronic cases the incidence of Bankart or ALPSA lesions was 97.11% (101/104) (P = .002). In the group with acute dislocations there was a Hill-Sachs lesion in 15 cases (65.21%) and chronic recurrent instability accounted for 97 cases (93.26%) (P = .001). The capsule was considered lax in 2 patients with acute instability and 31 patients with chronic instability (8.69% v 29.8%, P = .037). The overall frequency of SLAP lesions was not statistically significant between acute and chronic cases (P = .868), unlike their distribution. In acute cases there were 3 type I and 2 type II SLAP lesions, whereas in chronic cases there were 4 type I, 13 type II, 3 type III, and 1 type IV SLAP lesions. Loose bodies were found and removed in 17 chronic and 4 acute cases (16.34% v 13.04%, P = .903). A partial-thickness articular rotator cuff tear was found in 14 patients: 12 with chronic dislocations and 2 with acute dislocations (11.53% v 8.69%, P = .694). The cuff tears were partial articular surface tears, involving less than 25% of the cuff thickness, and were treated with debridement, and cuff repair was not necessary in any case. The inverted pear configuration of the glenoid was found in 16 cases with chronic instability (15.38%), whereas no patient with an acutely dislocated shoulder had an inverted pear-shaped glenoid (P = .044).
CONCLUSIONS: Associated, secondary intra-articular lesions are more frequent in patients with chronic compared with acute shoulder instability, probably as a result of the repeated dislocation or subluxation episodes. LEVEL OF EVIDENCE: Level IV, prognostic case series.