Purpose

Various alignment philosophies for total knee arthroplasty (TKA) have been described, all striving to achieve excellent long-term implant survival and good functional outcomes. In recent years, in search of higher functionality and patient satisfaction, a shift towards more patient-specific alignment is seen. Robotics is the perfect technology to tailor alignment. The purpose of this study was to describe ‘inverse kinematic alignment’ (iKA) technique, and to compare clinical outcomes of patients that underwent robotic-assisted TKA performed by iKA versus adjusted mechanical alignment (aMA).

Objective: This study evaluates the preoperative conventional anteroposterior radiography in non-operated patients with cuff tear arthropathy. It analyses the radiological findings in relation to the status of the rotator cuff and clinical outcome. The aim of the study is to define the usefulness of this radiographical examination in cuff tear arthropathy.

Methodology: This study analyses the preoperative radiological (AP-view, (Artro-)CT-scan or MRI-scan) and clinical characteristics (Constant-Murley-score plus active and passive mobility testing) and the peroperative findings in a cohort of 315 patients of which 282 had eccentric omarthrosis according to the classification of Hamada and 33 patients with centered omarthrosis who have at least two irreparable tendon tears. Those patients were part of a multicenter, retrospective, consecutive study of the French Orthopaedic Society (SOFCOT-2006). All patients had no surgical antecedents and were all treated with prosthetic shoulder surgery for a painful irreparable cuff tear arthropathy (reverse -(84%) or hemi-(8%) or double cup prosthesis (8%)).

Results: Fatty degeneration of a rotator cuff muscle decreases its strength (p < 0.0001).

In the presence of tendons lesser bony wear is seen at the acromion (acetabularisation, (p< 0.005), the glenoid (superomedial wear p=0.005) as well as the humeral head (femoralization, p=0.002).

The radiological classifications according to Hamada and Favard seem not to be as appropriate to reflect accurately the location and extent of the tendino-muscular degeneration as the acromial acetabularization and humeral sphericity.

The acromio-humeral distance is a good indicator for the location and the extend of the cuff tear arthropathy. A smaller acromio-humeral distance (95% CI: 4mm + 1) is only present if the postero-superior muscles are fatty degenerated (Goutallier stade III & IV) and a larger distance is calculated (95% CI: 7mm + 3) when only the antero-superior muscles are diseased.

The coracoid tip in cuff tear arthropathy-patients is almost always positioned in the inferior half of the glenoid (84%).

A bigger supero-inferior distance of the glenoid in relation to the radius of the humeral head indicates more structural destruction of rotator cuff status (tendinous and muscular) and a worse clinical outcome.

Conclusion: This study defines the use of a conventional radiological antero-posterior view to evaluate eccentric omarthrosis as very useful. The direction of eccentricity in the scapular plane of the body and type of wear, situated either at the glenoïd, acromion or humeral head are determined by the location and extent of the tendinous lesion and the degree of fatty degeneration of the rotator cuff muscle.