Purpose

The measurement of radial head translation about the capitellum (in percent): the radio-capitellum ratio (RCR) has proven to have excellent inter- and intra-observer reliabilities when measuring the RCR on a lateral radiological view of elbows at 90° of flexion and in the neutral position of the forearm. However, in the clinical setting, radiographs may be taken with the elbow in different positions. However, the purpose was to validate the RCR measurement method on elbows in different positions in flexion-extension and in different positions of the forearm in pronation-supination.

Purpose: The literature contains little information on an objective method of measuring radiocapitellar joint translations, as would be seen with joint instability. The purpose of this study was to develop and validate a measurement method that was simple and that could be easily reproducible in a clinical setting or intra-operatively to assess radiocapitellar joint translations.

Method: We performed a radiological study on a synthetic elbow specimen in order to quantify radial head translations as related to the capitellum: the Radio-capitellum ratio (RCR). Thirty (30) lateral elbow x-rays were taken in different magnitude of subluxation of the radial head. The subluxation was created randomly by manipulation. X-rays where taken by fluoroscopy to obtain a perfect lateral view of the distal humerus. First, the evaluators determined the long axis of the radius and the center of the capitellum. The displacement of the radial head (in mm) was obtained by measuring the distance of the line perpendicular to the long axis of the radius passing through the center of the capitellum. Then, in order to adjust for variation of magnification, a ratio of the displacement of the radial head about the diameter of the capitellum was done. The RC ratio would be of zero because the long axis of the radius always crosses the center of the capitellum in a perfectly aligned joint. A five mm translation of the radial head and a capitellum diameter of twenty (20) mm would give a RCR of 25% and would be positive if anterior and negative if posterior. The measurements were done two times at one week intervals by three independent evaluators to test inter-observer agreement and intra-observer consistency. The radiological incidences were randomly ordered to minimize observer recall bias. Intra/inter-observer reliability was calculated using Intra-Class Correlation (ICC) and paired T-tests.

Results: The mean translation in the trial group was of 6,06% (SD 70.7%) from – 167% to 125%. A result over 100% means that it is a complete dislocation ie – the axis of the radius is outside of the capitellum. Negative values signify posterior translation and positive values an anterior translation. Intra-observer reliability was excellent for the Radio-capitellum ratio (ICC 0.988 and 0.995) and inter-observer reliability was excellent (ICC 0.984 in average). Paired T-test results confirm a high intra-observer repeatability (p=0.97 and p=0.99) as well as a large inter-observer reproducibility (p=0.98 in average).

Conclusion: The proposed measurement of radial head translation about the capitellum (in percent): radio-capitellum ratio (RCR) has excellent inter – and intra-observer reliability when using our measurement method.

Purpose: Anatomic repair of an acute distal biceps tear has been demonstrated to improve flexion and supination strength compared with conservative treatment. The most commonly used fixation methods for a distal biceps tendon repair include suture anchors, bioabsorbable screws, and endobutton. The goal of this study was to

perform a radiologic evaluation of bioabsorbable screw tunnel osteolysis and

Method: We included twenty (20) consecutive patients who underwent primary anatomic repair of the distal biceps tendon since 2005. We used a 7x23mm biote-nodesis^® screw (Arthrex) in 18 cases, and 8x23mm and 8x12mm screws in the other two cases. First, from the x-ray view done in the immediate postoperative period showing the complete screw tunnel, we measured the ratio of the volume of the bone tunnel to the volume of the radius bone section. A mathematical formula for cylindrical volume was used (¶ x r2 x h). We used a relation between two volumes rather than the tunnel volume itself for scaling purposes. Secondly, we calculated the same relation on the x-ray from the last follow-up. We then obtained the percentage of tunnel enlargement by relating the volumetric ratio from the first x-ray to the ratio from the last x-ray. Afterwards, we performed a retrospective chart review noting any bioabsorbable screw-related and postoperative complications.

Results: In the group, the average age was forty-six (46) years. All subjects were male. Eighteen (18) cases were acute complete ruptures operated in the first three weeks, one case was a partial rupture and one case was chronic (one year). The average follow up was eighteen (18) months. We found that the average initial relative volume occupied by the screw tunnel was 47 % of the bone section. At the last follow-up, this volume increased to 68%. After our chart review, we found that one patient presented with a broken screw and increased pain and that another patient developed a severe foreign-body reaction with re-rupture of the tendon requiring three reoperations.

Conclusion: The use of a bioabsorbable screw for distal biceps tendon fixation results in significant osteolysis of the radial bone at short term follow-up. Consequences of osteolysis in the radius are worrisome since iatro-genic fractures are more likely to occur. Osteolysis can be secondary to an inflammatory reaction to the screw material, bone necrosis secondary to pressure or initial thermal necrosis. We also noted two cases of severe bio-tenodesis screw-related complications among our series of twenty (20) patients. These results call into question the use of the bioabsorbable screw in distal biceps tendon repair and are important to present. Exact volume of bone loss using 3D computed tomography scan analysis as well as quality of life questionnaires and strength testing will be available for presentation.