Patient-specific risk profile associated with early-onset primary osteoarthritis of the shoulder: is it really primary?

Abstract

Introduction: Although age is considered to be the major risk factor of primary glenohumeral osteoarthritis (GOA), younger population may suffer from degenerative changes of the shoulder joint without evidence of any leading cause. The purpose of this study was to investigate the risk profile in young patients suffering from presumably primary GOA.

Methods: A consecutive group of 47 patients undergoing primary shoulder arthroplasty for early-onset GOA below the age of 60 years at time of surgery was retrospectively identified and prospectively evaluated. Patients with identifiable cause for GOA (secondary GOA) were excluded. The resulting 32 patients (mean age 52 ± 7 years; 17 male, 15 female) with primary GOA were matched by age (± 3 years) and gender to 32 healthy controls (mean age 53 ± 7 years; 17 male, 15 female). Demographic data and patient-related risk factors were assessed and compared among both groups to identify extrinsic risk factors for primary GOA. Patients were further subdivided into a group with concentric GOA (group A) and a group with eccentric GOA (group B) to perform a subgroup analysis.

Results: Patients had a significantly higher BMI (p = 0.017), were more likely to be smokers (p < 0.001) and to have systematic diseases such as hypertension (p = 0.007) and polyarthritis (p < 0.001) and a higher Shoulder Activity Level (SAL) (p < 0.001) when compared to healthy controls. Furthermore, group B had a significantly higher SAL not only compared to healthy controls but also to group A, including activities such as combat sport (p = 0.048) and weightlifting (p = 0.01).

Conclusions: Several patient-specific risk factors are associated with primary GOA in the young population, as well as highly shoulder demanding activities in the development of eccentric GOA. Consequently, a subset of young patients with eccentric primary GOA could in reality be secondary due to a muscular imbalance between internal and external rotators caused by improper weight training.

Level of evidence: III, Case-Control study.

Keywords: Eccentric osteoarthritis; Primary glenohumeral osteoarthritis; Risk profile; Young population.

Fig. 1

Pie chart showing an overview of primary and secondary glenohumeral osteoarthritis (GOA) among the study population (n = 32). If an open or arthroscopic stabilization surgery or rotator cuff repair was performed (i.e. term “previous surgery”), patients were excluded

Fig. 2

Preoperative radiographics of a 40-year-old male patient. The BMI is 29, he is a current smoker and the shoulder-activity level is 4 with participating in boxing, combat sport and weightlifting. He used to be a professional bodybuilder. a–c Conventional x-rays with a.p. a and axial b images revealing a severe primary glenohumeral osteoarthritis (GOA) of the left shoulder. Computed tomography scan showed a posterior subluxation of the humeral head with posterior glenoid erosion. d–f Three years later, the patient presented with progressive shoulder complaints on the contralateral shoulder. Radiographs revealed a similar posterior eccentric GOA of the right shoulder joint

Fig. 3

Pie chart demonstrating our findings with regard to the pathogenesis of glenohumeral osteoarthritis (GOA) in a young population (n = 32)