Introduction

In patients with shoulder pain one of the important initial determinations is to assess the integrity of the rotator cuff. Clinical examination is often inconclusive. Compared with MRI and arthrography, ultrasound allows dynamic evaluation, is non-invasive, less expensive, less time-consuming and more acceptable to patients. The aim of the present study was to evaluate the accuracy of high resolution shoulder ultrasonography compared with arthroscopy in a series of consecutive patients with clinically suspected rotator cuff disease.

Introduction: Pain and mass lesions around hip resurfacing are reported with increasing frequency. The aetiology is unknown but reaction to metal wear debris and mechanical impingement have both been suggested. We are aware of a group of our patients with significant pain following resurfacing. We sought to correlate metal ion levels with X-ray findings and any local soft tissue reaction around the prosthesis.

Methods: Patients with significant groin pain following hip resurfacing were identified from routine clinics. Blood was tested for cobalt and chromium levels using inductively coupled mass spectrometry in all patients. Cup abduction angle and femoral stem version were estimated from plain radiographs. Patients underwent ultrasound scan (USS) of the affected hip joint. Bilateral prostheses were excluded to avoid confounding.

Results: 47 unilateral painful hip resurfacings (24 female) were identified. USS was performed in 42 patients and was abnormal in 25 (15 female). Abnormalities ranged from simple joint effusion with or without synovial thickening, through to cystic masses in the posterior joint and solid masses related to the ileopsoas tendon similar to the appearances previously described in pseudotumours.

A two sample t-test demonstrated cobalt and chromium ion levels were significantly higher in patients with abnormalities on USS (p=0.038, p=0.05 respectively), patients with normal USS were more likely to have a retroverted femoral component (p=0.01).

Discussion: We describe two groups of patients with a painful hip resurfacing: those with raised metal ions and local soft tissue reaction, and those with lower metal ions and no soft tissue reaction. The retroverted stems in the second group could cause an iatrogenic cam-type impingement. Metal ion levels are useful to guide further imaging. Raised levels should prompt investigation for a soft tissue abnormality with either USS or MRI, lower levels suggest investigation should look for mechanical impingement with imaging such as CT.

The use of high resolution ultrasonography for the detection of rotator cuff tears has achieved only limited acceptance by orthopaedic surgeons. Uncertainty about the accuracy of ultrasonography may be a contributing factor. The purpose of this study was to evaluate the accuracy of high-resolution ultrasonography compared to shoulder arthroscopy in the detection of rotator cuff tears. 100 consecutive patients with shoulder pain in whom arthroscopic surgery was planned underwent standardized preoperative ultrasonography. The ultrasound examinations were done by a single experienced musculoskeletal radiologist using a standard protocol. The findings at ultrasound were classified into intact cuff, tendinopathy, partial-thickness tear, and full-thickness rotator cuff tears. The size of the tear was measured in centimetres. The location was designated as subscapularis, supraspinatus, infraspinatus, or a combination. All of the subsequent shoulder arthroscopies were done by a single surgeon. The presence or absence of a rotator cuff tear and the size and extent of the tear when present were recorded. We then compared the ultrasonographic findings with the definitive operative findings. For the detection of rotator cuff tears, ultrasound had a sensitivity of 95% and a specificity of 94%; accuracy 95%. There was 100% sensitivity for full thickness tears (specificity 91% and accuracy 95%), while for partial-thickness tears there was a sensitivity of 80%, (specificity 98% and accuracy 95%). In experienced hands, ultrasound is a highly accurate diagnostic method for detecting rotator cuff tears. The results of this study compare favourably with the published results of magnetic resonance imaging for the investigation of this condition. Furthermore, dynamic imaging and comparison with the opposite shoulder is possible with ultrasonography.