• Hip instability following total hip arthroplasty (THA) remains a major challenge and is one of the main causes of revision surgery.

• Dual mobility (DM) implants have been introduced to try to overcome this problem. The DM design consists of a small femoral head captive and mobile within a polyethylene liner.

• Numerous studies have shown that DM implants reduce the rate of dislocation compared to fixed-bearing inserts.

• Early designs for DM implants had problems with wear and intra-prosthetic dislocations, so their use was restricted to limited indications.

• The results of the latest generation of DM prostheses demonstrate that these problems have been overcome. Given the results of these studies presented in this review, surgeons may now consider DM THA for a wider patient selection.

Cite this article: EFORT Open Rev 2019;4:541-547. DOI: 10.1302/2058-5241.4.180045

• Chronic traumatic anterior shoulder instability can be defined as recurrent trauma-associated shoulder instability requiring the assessment of three anatomic lesions: a capsuloligamentous and/or labral lesion; anterior glenoid bone loss and a Hill–Sachs lesion.

• Surgical treatment is generally indicated. It remains controversial how risk factors should be evaluated to decide between a soft-tissue, free bone-block or Latarjet-type procedure.

• Patient risk factors for recurrence are age; hyperlaxity; competitive, contact and overhead sports. Trauma-related factors are soft tissue lesions and most importantly bone loss with implications for treatment.

• Different treatment options are discussed and compared for complications, return to sports parameters, short- and long-term outcomes and osteoarthritis.

• Arthroscopic Bankart and open Latarjet procedures have a serious learning curve. Osteoarthritis is associated with the number of previous dislocations as well as surgical techniques.

• Latarjet-type procedures have the lowest rate of dislocation recurrence and if performed correctly, do not seem to increase the risk of osteoarthritis.

• Variable definitions of pseudoparalysis have been used in the literature.

• Recent systematic reviews and biomechanical studies call for a grading of loss of force couple balance and the use of the terms ‘pseudoparesis’ and ‘pseudoparalysis’.

• Pain should be excluded as the cause of loss of active function.

• Key players for loss of force couple balance seem to be the lower subscapularis as an anterior inferior checkrein and the teres minor as a posterior inferior fulcrum.

• Loss of three out of five muscle–tendon units counting upper and lower subscapularis separately is predictive of pseudoparalysis.

• Shoulder equator concept: loss of all three posterior, or all three superior, or all three anterior muscle–tendon units is predictive of pseudoparalysis (loss of fulcrum for deltoid force).

• Every effort should be made to prevent propagation of rotator cuff tears into the subscapularis and posterior rotator cuff (infraspinatus and teres minor) to maintain force couple balance (value of partial cuff repair).

• Clinical assessment of active forward elevation, active external rotation, and active internal rotation is important to define and grade the severity of loss of force couple balance.

• Additional features such as patient age, traumatic aetiology, chronicity, fatty infiltration, and stage of cuff tear arthropathy are useful for a specific diagnosis with implications for treatment.

• Decision-making for the treatment of pseudoparalytic shoulders is complex and a high level of experience in shoulder surgery and outcome evaluation is required.

• Management and results depend on clinical findings, tear and tissue quality, patient and surgeon criteria. Clinical findings determine the exact definition and direction of pseudoparesis and pseudoparalysis.

• Tear pattern and tissue quality determine if the rotator cuff is repairable or irreparable. Age and general health are important patient factors.

• Non-operative treatment is the first option for patients with a higher risk profile for reconstruction or arthroplasty, but delineation of its value requires better evidence.

• Tendon transfers are used for irreparable loss of the horizontal force couple balance (rotation). Options include latissimus dorsi, pectoralis minor and major for loss of active internal rotation, and latissimus dorsi ± teres major and lower trapezius for loss of active external rotation (AER).

• Partial cuff repair with or without superior capsular reconstruction using allograft or biceps tendon is an option for loss of active forward elevation.

• Treatment for the combined loss of elevation and external rotation patients is still not clear. Options include lateralised reverse shoulder arthroplasty (RSA) alone or combined RSA with a tendon transfer.

• RSA with loss of AER can be revised by adding a tendon transfer.