Long term results of Arthroscopic Capsular Shrinkage for Palmar Midcarpal Instability of the wrist
Matthew R Ricks, BSc MBBS MSc MSc FRCS Tr & Ortho, David Hargreaves, MBBS FRCS Orth and Peter Belward, BSc, University Hospital Southampton, Southampton, United Kingdom
Midcarpal Instability is a term for a collection of poorly understood conditions where the proximal row of the carpus is unstable. The most common type of Midcarpal instability is palmar midcarpal instability (PMCI). Treatment for PMCI includes non-operative proprioceptive retraining of the wrist, splints, and strengthening. If this fails various authors have suggested a number of different fusion, tenodesis procedures or capsular shrinkage. There are no long-term case series in the literature. The aim of this study is to assess the long-term results of arthroscopic capsular shrinkage when used for palmar midcarpal instability of the wrist.
A prospective cohort study of patients who underwent arthroscopic capsular shrinkage for PMCI was carried out. Ethical board approval was given for this study. All patients were followed up and reviewed independently from the operating surgeon. Assessment included a structured questionnaire, a DASH questionnaire and clinical examination using a goniometer. PMCI was assessed objectively with the anterior drawer test and radiological imaging was only performed if clinically relevant to the residual symptoms.
13 patients (15 wrists) underwent arthroscopic capsular shrinkage for PMCI. 12 patients (14 wrists) were available for clinical review with a follow up rate of 92.3%. The mean time from index procedure to final review was 12 years (Range 10-14years). The symptoms of instability had completely resolved in 9 wrists (7 patients). Only 2 of the 14 wrists had symptoms that were reproduced with a positive anterior drawer test. All other wrists were stable on objective assessment. The mean DASH score had improved from pre op of 34 to post op of 12.1 and at 12year follow up this had deteriorated minimally to 15.3. The patients rated that 9 wrists were much better than pre-surgery, 3 as better, one unchanged and one worse
There are no studies looking at the long-term natural history of treatments for PMCI. This is the first long term study from any joint, where the results of capsular shrinkage have been maintained over time. In this series, we have not seen any deleterious effect from possible mechanoreceptor injury. We suspect that functioning mechano-receptors are more relevant in the unstable joint, than the structurally stable joint. The authors propose that thermal capsular shrinkage is an effective and durable option for use in mild to moderate forms of PMCI.
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