F. Van Glabbeek

Detrimental Effects of Overstuffing or Understuffing with a Radial Head Replacement in the Medial Collateral-Ligament Deficient Elbow

BACKGROUND Comminuted radial head fractures associated with an injury of the medial collateral ligament can be treated with a radial head implant. We hypothesized that lengthening and shortening of the radial neck would alter the kinematics and the pressure through the radiocapitellar joint in the medial collateral ligament-deficient elbow. METHODS The effects of lengthening (2.5 and 5 mm) and shortening (2.5 and 5 mm) of the radial neck were assessed in six human cadaveric upper extremities in which the medial collateral ligament had been surgically released. The three-dimensional spatial orientation of the ulna was recorded during simulated active motion from extension to flexion. Total varus-valgus laxity and ulnar rotation were measured. Radiocapitellar joint pressure was assessed with use of pressure-sensitive film. RESULTS Radial neck lengthening or shortening of >/=2.5 mm significantly changed the kinematics in the medial collateral ligament-deficient elbow. Lengthening caused a significant decrease (p < 0.05) in varus-valgus laxity and ulnar rotation (p < 0.05), with the ulna tracking in varus and external rotation. Shortening caused a significant increase in varus-valgus laxity (p < 0.05) and ulnar rotation (p < 0.05), with the ulna tracking in valgus and internal rotation. The pressure on the radiocapitellar joint was significantly increased after 2.5 mm of lengthening. CONCLUSIONS This study suggests that accurate restoration of radial length is important and that axial understuffing or overstuffing of the radiohumeral joint by >/=2.5 mm alters both elbow kinematics and radiocapitellar pressure. CLINICAL RELEVANCE This in vitro cadaver study indicates that a radial head replacement should be performed with the same level of concern for accuracy and reproducibility of component position and orientation as is appropriate with any other prosthesis.

Validation of the lesser sigmoid notch of the ulna as a reference point for accurate placement of a prosthesis for the head of the radius: a cadaver study.

We undertook a study on eight arms from fresh cadavers to define the clinical usefulness of the lesser sigmoid notch as a landmark when reconstructing the length of the neck of the radius in replacement of the head with a prosthesis. The head was resected and its height measured, along with several control measurements. This was compared with in situ measurements from the stump of the neck to the proximal edge of the lesser sigmoid notch of the ulna. All the measurements were performed three times by three observers acting independently. The results were highly reproducible with intra- and interclass correlations of > 0.99. The mean difference between the measurement on the excised head and the distance from the stump of the neck and the lesser sigmoid notch was -0.02 mm (-1.24 to +0.97). This difference was not statistically significant (p = 0.78). The proximal edge of the lesser sigmoid notch provides a reliable landmark for positioning a replacement of the radial head and may have clinical application.

Does infrapatellar fat pad resection in total knee arthroplasty impair clinical outcome? A systematic review

INTRODUCTION The infrapatellar fat pad (IPFP) is often removed during total knee arthroplasty (TKA). No evidence based guidelines on changes in clinical outcome have yet been described. The aim of this review is to investigate whether regular removal of the IPFP during TKA should be performed. MATERIAL AND METHODS Seven databases were systematically searched. Clinical studies, in which TKA with IPFP resection was compared with IPFP preservation, were included. Risk of bias was assessed using the Cochrane collaboration tool. Studies reporting anterior knee pain, patellar tendon length, range of motion, patellar vascularisation or functional outcome were included. RESULTS The indication for TKA varied in the different studies: osteoarthritis (OA), rheumatic arthritis (RA) and multiple indications (OA, RA and osteonecrosis). After IPFP resection: 1. For OA, no differences in function, range of motion, and anterior knee pain were found. 2. In the RA study, there was a trend towards more discomfort and a decrease in function. 3. In OA and RA patients a decrease in patellar tendon length was observed. 4. One study reported no decrease in patellar vascularisation. DISCUSSION Limitations of this review are the high risk of bias scores of the included studies, the varying outcome measures, follow up, number and type of participants. Randomised clinical trials are required to support or refute the results, contributing to a possible future evidence based guideline on IPFP resection during TKA.

Tears of the supraspinatus tendon: assessment with indirect magnetic resonance arthrography in 67 patients with arthroscopic correlation

Background: Magnetic resonance (MR) arthrography is generally regarded as the gold standard for shoulder imaging. As an alternative to direct MR arthrography, the less invasive indirect MR arthrography technique was proposed, offering logistic advantages because fluoroscopic or ultrasonographic guidance for joint injection is not required. Purpose: To assess the diagnostic performance of indirect MR arthrography in the diagnosis of full- and partial-thickness supraspinatus tears in a symptomatic population. Material and Methods: Two radiologists with different levels of experience independently and retrospectively interpreted indirect MR (1.5T) arthrograms of the shoulder obtained in 67 symptomatic patients who underwent subsequent arthroscopy. On MR, the supraspinatus tendon was evaluated for full- or partial-thickness tear. With arthroscopy as the standard of reference, sensitivity, specificity, and diagnostic accuracy of indirect MR arthrography in the detection of full- and partial-thickness tears of the supraspinatus tendon was calculated. Kappa (κ) statistics were used for the assessment of the agreement between arthroscopic and imaging findings and for the assessment of interobserver agreement. Results: For full-thickness tears of the supraspinatus tendon, sensitivities, specificities, and accuracies exceeded 90% for both observers, with excellent interobserver agreement (κ = 0.910). For partial-thickness tears, sensitivities (38–50%) and accuracies (76–78%) were poor for both reviewers, and interobserver agreement was moderate (κ = 0.491). Discrepancies between MR diagnosis and arthroscopy were predominantly observed with small partial-thickness tears. Conclusion: Indirect MR arthrography is highly accurate in the diagnosis of full-thickness rotator cuff tears. However, the diagnosis of partial-thickness tears with indirect MR arthrography remains faulty, because exact demarcation of degenerative change and partial rupture is difficult. On the basis of the above findings, we do not recommend indirect MR arthrography on patients for whom rotator cuff disease is suspected clinically.