Anterior Shoulder Instability in the Aging Population: MRI Injury Pattern and Management.

BACKGROUND. Literature on glenohumeral dislocations has focused on younger patient populations because of high recurrence rates. However, the spectrum of injuries sustained in younger versus older patient populations is reported to be quite different. OBJECTIVE. The purpose of this article is to describe MRI findings and management of anterior shoulder instability in the aging (≥ 60 years) population. METHODS. Shoulder MRI examinations of anterior glenohumeral dislocations in patients 40 years old and older were subdivided into groups younger than 60 years old or 60 years old and older and reviewed by two musculoskeletal radiologists for a Hill-Sachs lesion, other fracture, glenoid injury, capsulolabral injury, rotator cuff tear, muscle atrophy, and axillary nerve injury. Fischer exact test and logistic regression was evaluated for significant differences between cohorts, and interreader agreement was assessed. Surgical management was recorded, if available. RESULTS. A total of 104 shoulder MRI examinations (age range, 40-79 years; mean age, 58.3 years; 52 women, 52 men) were reviewed (54 examinations < 60 years; 50 examinations ≥ 60 years). Acute high-grade or full-thickness supraspinatus (64.0% vs 37.0%; p = .001), infraspinatus (28.0% vs 14.8%; p = .03), and subscapularis (22.0% vs 3.7%; p = .003) tears were more common in the group 60 years old and older. Hill-Sachs lesions were more common in the younger group (81.5% vs 62.0%; p = .046). Greater tuberosity fractures were seen in 15.4% of the overall cohort, coracoid fractures in 4.8%, and acute axillary nerve injuries in 9.6%. Interreader concordance was 88.5-89.4% for rotator cuff tears and 89.4-97.1% for osseous injury. In the group younger than 60 years old, 11 of 37 subjects (29.7%) had rotator cuff repair and 11 of 37 (29.7%) had labral repair, whereas 17 of 36 (47.2%) of the older group underwent rotator cuff repair, six of 36 (16.7%) underwent reverse shoulder arthroplasty, and six of 36 (16.7%) underwent labral repair. CONCLUSION. Radiologists should have a high index of suspicion for acute rotator cuff tears in anterior shoulder instability, especially in aging populations. Greater tuberosity or coracoid fractures and axillary nerve injury occur across all ages, whereas Hill-Sachs injuries are more common in younger patients. CLINICAL IMPACT. Acute high-grade or full-thickness rotator cuff tears are seen with higher frequency in older populations after anterior glenohumeral dislocation. Osseous and nerve injuries are important causes of patient morbidity that if not carefully sought out may be overlooked by the interpreting radiologist on routine imaging.

Fibular Tip Periostitis: New Radiographic Sign Predictive of Chronic Peroneal Tendon Subluxation-Dislocation in Pes Planovalgus.

BACKGROUND. Tearing of the superior peroneal retinaculum is a known cause of peroneal tendon subluxation-dislocation. However, with the exception of cortical avulsions at the fibular attachment, superior peroneal retinaculum injury and subsequent peroneal tendon subluxation-dislocation are typically radiographically occult. OBJECTIVE. The purpose of this study was to evaluate the previously undescribed association between radiographic fibular tip periostitis and MRI evidence of peroneal tendon subluxation-dislocation in patients with hindfoot valgus. METHODS. Thirty-five patients with radiographic fibular tip periostitis and 35 ageand sex-matched individuals without periostitis were selected from among 220 consecutively registered patients with hindfoot valgus who had undergone both ankle radiography and MRI. Studies were retrospectively assessed by two musculoskeletal radiologists in consensus and by two additional blinded radiologists independently for the presence of peroneal tendon subluxation-dislocation, presence of subfibular impingement, and hindfoot valgus angle measurements. Interobserver agreement and accuracy, sensitivity, and specificity in the detection of fibular periostitis, peroneal tendon subluxation-dislocation, and subfibular impingement were calculated, and Fischer exact, Mann-Whitney, kappa coefficient, and intraclass correlation tests were performed. RESULTS. Both the consensus and the two independent interpretations showed that the frequency of peroneal tendon subluxation-dislocation was significantly greater in the group with periostitis (62.9%, 65.7%, and 85.7%) than in the group without periostitis (5.7%, 0%, and 14.3%) (p < .001). The finding of periostitis was specific and highly sensitive for predicting peroneal tendon subluxation-dislocation. The frequency of subfibular impingement was also statistically higher in the group with periostitis than in the group without it (p < .001). The hindfoot valgus angle was statistically larger in the group with periostitis than in the control group (p = .01-.002) and among patients with versus those without peroneal tendon subluxation-dislocation (p = .002 to p < .001). The blinded readers had substantial or almost perfect agreement on all imaging interpretations (concordance rate, 82.9-95.7%; κ = 0.66-0.91). CONCLUSION. The radiographic finding of fibular tip periostitis in patients with hindfoot valgus can be a predictor of peroneal tendon subluxation-dislocation and may also suggest advanced hindfoot valgus and subfibular impingement. These radiographic associations should be recognized by the radiologist, and MRI may be recommended as clinically indicated. CLINICAL IMPACT. Chronic undiagnosed peroneal tendon subluxation-dislocation can be a persistent cause of lateral ankle pain, leading to further degeneration and the possibility of complete peroneal tendon tears. Distal fibular periostitis in patients with hindfoot valgus can be a reliable radiographic indicator of this entity and may suggest the presence of subfibular impingement.