Pectoralis major insertional ratio in proximal humerus fractures: a method to reconstruct humeral head height in arthroplasty.

A key factor for a successful outcome after hemiarthroplasty for a 4-part proximal humerus fracture is accurately restoring humeral length. Our hypothesis was that the pectoralis major insertion is not at a constant distance on the humerus, as has been previously suggested, but varies depending on the length of the humerus, and our goal was to determine if a consistent ratio exists for the insertion as it relates to total humeral length. Thirty-eight cadaver arms were dissected to expose the pectoralis major insertion. Using a digital caliper, measurements were made from the top of the humeral head to the superior aspect of the pectoralis major insertion (HP), and from the pectoralis insertion to the lateral epicondyle (PL). The predictive ability of PL for HP was examined via regression, and the average prediction error was computed. The final predictive regression model had the following formula: pHP=0.2323xPL, where pHP is predicted HP. This equation had an average prediction error of 4.11 mm. The PL can be measured intraoperatively during hemiarthroplasty for proximal humerus fractures. The proportionality relationship can then be used to predict HP with an average prediction error <5 mm. This relationship may facilitate accurate intraoperative reconstruction of prosthetic head height and enhance existing techniques for assessment of implant positioning.

Posterior and multidirectional instability of the shoulder.

The shoulder is an inherently unstable joint that is subject to different patterns of instability. Determining the direction of subluxation that is causing the patient's symptoms can be difficult. Although posterior and multidirectional instability share many characteristics, they have different etiologies and treatment requirements. Multidirectional instability was first described in 1980 by Neer and Foster, but the continuing lack of a consistent definition for the condition contributes to difficulty in both diagnosis and treatment. Posterior instability has been more precisely defined, but the diagnosis nonetheless can be difficult. For most patients with either condition, rehabilitation and bracing are the preferred treatment. If nonsurgical treatment is unsuccessful, arthroscopic treatment can provide a satisfactory result.

A combined technique for distal biceps repair using a soft tissue button and biotenodesis interference screw.

BACKGROUND: There are many techniques described to repair acute distal biceps tendon ruptures. The authors' objective is to report the results of a single-incision technique using a combination of a soft tissue button and biotenodesis interference screw with accelerated rehabilitation. HYPOTHESIS: Dual fixation of a distal biceps rupture will allow for early return to function. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: From February 2004 to July 2007, 41 elbows in 40 patients had repair of an acute distal biceps tendon rupture (<6 weeks) through an anterior incision using a soft tissue button and interference screw combined technique. The patients were evaluated pre- and postoperatively with a physical examination, radiographs, and the Andrews-Carson elbow score. Nine patients were unavailable for follow-up. The remaining 31 patients (32 elbows) were contacted for a telephone interview at an average of 24 months postoperatively. RESULTS: The preoperative Andrews-Carson score averaged 168 and the postoperative Andrews-Carson score averaged 196 points at final clinical follow-up. There was a statistically significant difference between the pre- and postoperative Andrews-Carson scores (P < .001). One patient had heterotopic ossification associated with decreased pronation and supination. Two superficial radial nerve palsies completely resolved by final follow-up. The average postoperative time to resume normal activities or return to work was 6.5 weeks. CONCLUSION: Repair of acute distal biceps tendon ruptures using a soft tissue button and interference screw technique through a limited anterior incision can allow for accelerated rehabilitation and early return to function.

Posterior cruciate ligament reconstruction: Achilles tendon allograft, double bundle.

Allograft usage for cruciate ligament reconstruction has gained in popularity. Many techniques are described for posterior cruciate reconstruction with both autograft and allograft tendons. Achilles tendon allograft is a versatile and effective graft that can be used for a transtibial, double femoral bundle posterior cruciate reconstruction.

Anthropometry of the human scaphoid.

PURPOSE: Internal fixation has become a well-established alternative to casting for acute scaphoid fractures. Screw design has evolved, and several different types of screws of varying sizes are now available. The purpose of this study was to establish morphometric data for the human scaphoid, document variation in scaphoid dimensions between genders, and to evaluate symmetry in scaphoid measurements between the two sides. METHODS: We measured length, width, and morphology of the scaphoid in 30 paired cadaveric specimens with reference to the long axis of the scaphoid from the proximal pole to the distal articular surface. The width of the bone was compared with diameters of commercially available screws. RESULTS: When measured along an axis from proximal pole to the distal articular surface, male scaphoids (31.3 mm +/- 2.1) were significantly longer than female specimens (27.3 mm +/- 1.7). The male scaphoid was also significantly wider than the female specimen when measured perpendicular to the long axis 2 mm from the proximal pole (4.5 mm +/- 1.4 vs 3.7 mm +/- 0.5) and at the waist (13.6 mm +/- 2.6 vs 11.1 mm +/- 1.2). There was no significant difference in the distal pole diameter measured 2 mm from the tip between genders (7.2 mm +/- 1.0 vs 7.2 mm +/- 1.2). The diameters of most commercially available standard screws were larger than the proximal pole of the female scaphoid. CONCLUSIONS: Allowing for countersinking of the screw 2 mm beneath either pole, our data suggest the usual screw length will be 27 mm and 23 mm for male and female scaphoids, respectively. The small width of the proximal pole of the female scaphoid will not accommodate standard-sized screws from most manufacturers, and consideration must be given to distal to proximal screw placement or use of "mini" screws if the implant is to be inserted in a proximal to distal direction.