Paper 90: Clinical Evaluation of Surgical Treatments for Lateral Type Osteochondritis Dissecans of the Humeral Capitellum

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ABSTRACTS

BERNARD R BACH JR, MD, USA NIKHIL N VERMA, MD, USA MATTHEW THOMAS PROVENCHER, MD, USA ABSTRACT Purpose: The articular contact pressures after both Latarjet and Iliac Crest Bone Graft (ICBG) for glenoid bone deficiency remains poorly defined. We investigated glenohumeral articular contact pressures in a clinically relevant glenoid bone loss model to: 1) determine if articular contact pressure could be restored after either a Latarjet or ICBG procedure, and 2) to determine the increase in pressure with proud, flush, and recessed Latarjet or ICBG procedures. Methods: A total of 12 fresh-frozen cadaveric shoulders stripped of all tissues except labrum and contact pressures in 4 equal quadrants of the glenoid were determined with a Tekscan flexible tactile force sensor. In serial static glenohumeral positions of scapular abduction (30o, 60o, and 60o with 90o external rotation) with a compressive load of 440N, the glenohumeral contact area, contact pressure, peak pressure, and peak force were determined for several conditions: 1) intact glenoid, 2) glenoid with clinically relevant 15% and 30% defect from 2:00 to 6:00, 3) 30% glenoid defect with Latarjet bone block placed 2mm proud, flush, and 2mm recessed to the glenoid, 4) 30% glenoid defect with iliac crest bone graft placed 2mm proud, flush, and 2mm recessed to the glenoid. Results: With a clinically relevant anterior glenoid bone defect of 30%, contact area decreased 35% (p⬍0.05) and mean contact pressure increased nearly 100% (p⬍0.01), with mean contact pressure in this quadrant increasing 400% (p⬍0.01). An ICBG placed in a flush position restored mean contact pressure to 85% (p⬍0.05) of the intact specimen. The Latarjet placed in a flush position restored mean contact pressure and force to 65% (p⬍0.02) of intact specimen, and demonstrated statistically higher pressure than the ICBG at nearly all positions (p⬍0.02). With 30% bone loss and bone grafts placed in a proud position, mean contact pressure increased 100% (p⬍0.01) in the posterior glenoid indicating a shift of pressure to the posterior glenoids; an additional 50% increase in pressure (p⬍0.01) was noted in the anteroinferior quadrant over the flush condition. Mean contact pressures and forces of bone grafts placed in a recessed position were not significantly different from those of 30% glenoid defect, however, edge-loading was significantly increased. Conclusions: Due to the inherent congruity of the ICBG versus the Latarjet, contact pressures and forces were lower in the glenoids bone loss model reconstructed with ICBG. Grafts placed in a proud position increased the

peak pressure not only at the graft location, but also posteroinferiorly suggesting a shift in the articular contact forces posteriorly. These findings may favor the potential clinical utility of ICBG versus Latarjet in an optimally placed position in glenoid defects based upon normalization of articular contact pressure. Paper 89: Radial Nerve Anatomy at the Elbow Joint: Guidelines for Arthroscopic Safety SHRINATH KAMINENI, FRCS(ORTH), UNITED KINGDOM, PRESENTING AUTHOR HARI KRISHNA ANKEM, MS (ORTH), DNB (ORTH), MRCS (EDIN, UK), INDIA ABSTRACT Purpose: To study the anatomy of the radial nerve at the elbow joint. Materials: Seventy fresh frozen cadeveric elbows were studied for the anatomy of the radial nerve, with respect to the adjacent and arthroscopically relevant bony landmarks. Measurements were taken with digital callipers, with the forearm in neutral, pronation, and supination. Results: The average transverse dimensions of the radial fossa and capitellum were 8.0mm (range 7.5 to 8.4), 17.0mm (range16.6 to 17.5) respectively. The radial head dimensions in supination, neutral and pronation were 24.8 mm (range 23.0 to 25.4), 25.20 mm ( range 23.0 to 25.9), and 24.75 mm ( range 23.0 to 25.3) respectively. The radial nerve translates medially upon the capitellum and radial head during pronation, with an average excursion of 1.8mm at the capitellum and 10.5mm at the radial head. During its course the radial nerve lies lateral to the medial edge of the radial fossa and the anterior margin of the proximal radioulnar joint, and on the medial half of the capitellum. A medial free space of 1.1 mm at the radial fossa, 3.4mm at the capitellum and 16.9mm at the radial head exists in supination. The medial free space in neutral rotation at the capitellum is 5.5mm. The medial free space in neutral rotation and pronation at the radial head is 13.1mm and 6.5mm respectively. Conclusion: When performing any arthroscopic anterolateral elbow compartment procedure, the radial nerve can be endangered if the anterior capsule is breached lateral to the medial radial fossa margin, or lateral to the proximal radio-ulnar joint. The radial nerve was not found to breach these anatomical landmarks in 70 consecutive cadaveric elbows. These simple intra-articularly accessible anatomical landmarks are safe guides for avoiding radial nerve injury. Paper 90: Clinical Evaluation of Surgical Treatments for Lateral Type Osteochondritis Dissecans of the Humeral Capitellum HAREHIKO TSUKADA, MD, JAPAN,

ABSTRACTS PRESENTING AUTHOR YASUYUKI ISHIBASHI, MD, JAPAN EIICHI TSUDA, MD, JAPAN AKIRA FUKUDA, MD, JAPAN YUJI YAMAMOTO, MD, JAPAN SATOSHI TOH, MD, JAPAN ABSTRACT Objective: Osteochondritis dissecans (OCD) of the humeral capitellum most frequently occurs in adolescent baseball players. The treatment for advanced OCD is controversial, especially, the prognosis of the extended lateral type OCD lesion which destroys the lateral wall of the humeral capitellum is poor. We performed two surgical procedures for these cases; first, osteochondral fragment fixation using autologous osteochondral plug for cases of preservationable osteochondral fragment with sufficient cancellous bone and acceptable congruity with reduction, and, second, replacement of the osteochondral fragment with osteochondral autograft for cases without preserved fragments. The objective of this study was to compare the clinical results between the fixation group and the replacement group. Methods: Nine patients were treated with fixation procedure (average age: 12.3 years, average follow-up period: 21.3 months) and 7 patients were treated with replacement procedure (average age: 14.4 years, average follow-up period: 21.2 months). First, arthroscopic evaluation was performed, followed by direct visualization of the OCD lesion by the posterolateral approach. In the fixation procedure, the osteochondral fragment was fixed with one or two osteochondral plugs of 5-6mm diameter obtained from the ipsilateral knee joint, and the elbow joint was immobilized in a long arm cast for 2 weeks after surgery. In the replacement procedure, the osteochondral fragment was resected, and replaced with an osteochondral plug of 9-10mm diameter obtained from the ipsilateral knee joint. All patients were evaluated with range of motion (ROM) of elbow joint, Timmerman’s scoring system, and the return to activity level. Postoperative radiographs and magnetic resonance imaging (MRI) were obtained for all patients, radiocapitellar congruity with 45 degree flexion view in radiographs and high signal intensity in the subchondral bone area in T2-weighted MRI were evaluated. Results: No significant difference between pre and post operative ROM was detected in either group. In the scoring system, the postoperative average of 185⫾18 points was statistically significantly higher than the preoperative average of 156⫾24 points in fixation group, and the postoperative average of 185⫾12 points was statistically significantly higher than the preoperative

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average of 149⫾35 points in the replacement group. All patients returned to full activity level except for one in the fixation group. No significant difference between the groups was detected in the period to return to full activity level. In the radiocapitellar congruity, the postoperative average of 80⫾15 % was statistically significantly higher than the preoperative average of 39⫾7 % in the fixation group, and the postoperative average of 70⫾17 % was statistically significantly higher than the preoperative average of 33⫾10 % in the replacement group. In the postoperative MRI evaluation, the high signal intensity in the subchondral bone area that was detected in the preoperative T2-weighted MRI was not detected in 5 cases in the fixation group and 7 cases in the replacement group. Discussion: This study indicated that both methods were effective for lateral type elbow OCD. It is important to make a choice between the methods based on the condition of the OCD lesion. Paper 91: Surgical Management of Unstable Elbow Dislocation without Intra-articular Fracture: Surgical Findings and the Results of Early Stabilization and Mobilization in 20 Patients SHINKUN KIM, MD, SOUTH KOREA, PRESENTING AUTHOR PREDRAG PAVLOVIC, MD, SERBIA & MONTENEGRO IVAN DRAGOLJUB MICIC, MD, PHD, SERBIA & MONTENEGRO IN-HO JEON, SOUTH KOREA ABSTRACT Background: The evaluation and management of unstable elbow dislocation with persistent subluxation after closed reduction remains variable and controversial. The purpose of this study was to describe soft tissue injury patterns and report the clinical results of primary ligament repair with use of protected early mobilization in unstable elbow dislocations with pure capsuloligamentous injuries. Materials and Methods: Twenty consecutive patients presented with traumatic unstable elbow dislocation without associated intra-articular fracture were reviewed. Clinical information, radiographs and intraoperative findings were collected. Anatomic repair was performed using metal anchor screws and bone tunnel method. All patients returned for radiographs and functional evaluation with use of Mayo Elbow Performance Score at a minimum of 24 months after the operation. Results: Ligament avulsion is noted in 55 % for MCL, 80% for LCL, 60% for flexor tendon, 80 % for extensor tendon. Some injury patterns had a high association of brachialis and anterior capsular injury. Overall mean