Thomas P. Branch

Is it important to secure the horns during lateral meniscal transplantation? A cadaveric study.

The purpose of this investigation was to determine if secure attachment of the horns of the lateral meniscus during transplantation affects the load-bearing function of the meniscus. Six knee joints were loaded in compression (310 N) and the interarticular contact pressure in the joint measured using pressure-sensitive film inserted into the joint. Each knee was tested first with the original intact meniscus and then after each of the following surgical procedures involving the original lateral meniscus: (1) total meniscectomy; (2) meniscal transplantation with a tibial bone bridge; (3) meniscal transplantation with neither horn secured; (4) meniscal transplantation with the anterior horn secured; (5) meniscal transplantation with the posterior horn secured; and (6) meniscal transplantation with both horns secured. The results are as follows. (1) The intact joint gave the largest contact area and the smallest peak contact pressure. The joint with the total meniscectomy gave the smallest contact area and the largest peak contact pressure. (2) A meniscal transplantation with either a tibial bony bridge or with both horns secured gave results similar to those for the intact joint. (3) A meniscal transplantation with only one horn secured gave results somewhere in between those for the intact joint and those for the joint without a meniscus. A meniscal transplantation with neither horn secured gave results similar to those for a joint without a meniscus.

The Role of the Acromioclavicular Ligaments and the Effect of Distal Clavicle Resection

To determine the role of the acromioclavicular liga ments in controlling scapular rotation about the distal clavicle and the effects of distal clavicle resection, we used 13 fresh shoulders consisting of the clavicle, acromioclavicular ligaments, coracoclavicular liga ments, and scapula. The range of motion was mea sured using a specially designed goniometer for each of the three orthogonal axes of rotation of the scapula with reference to the clavicle: anterior-posterior axial rotation, protraction-retraction, and abduction-adduc tion. We did two experiments involving sequential sec tioning. Range of motion was measured in the intact shoulder and after each sectioning cut. The order of sectioning in Experiment 1 (six shoulders) was 1) the inferior acromioclavicular ligament, 2) removal of 5 mm of the distal clavicle, and 3) the superior acromiocla vicular ligament. In Experiment 2 (seven shoulders) the order was 1) the superior acromioclavicular ligament, 2) removal of 5 mm of the distal clavicle, and 3) the inferior acromioclavicular ligament. The most important results were 1) only 5 mm of the distal clavicle needs to be resected to ensure that no bone-to-bone contact occurs in rotation postoperatively and 2) there was no difference in the end result (for range of motion in any of the three axes) whether the inferior acromioclavicu lar ligament or the superior acromioclavicular ligament was cut before removal of 5 mm of the distal clavicle.

Optimal graft fixation--the effect of gap size and screw size on bone plug fixation in ACL reconstruction.

In reconstruction of the anterior cruciate ligament (ACL), using central one-third patellar tendon graft, an early weak link is the bone plug junction. To study this, we carried out experiments to determine the relationship between gap size, screw size, and pullout force of patellar bone plugs inserted in the femur of the porcine model. Forty-nine porcine knees were obtained. Holes 11 mm in diameter were drilled in the intercondylar notch of the femur. Bone plugs fashioned from the patella were made to fit the holes with gap sizes of 1, 2, 3, or 4 mm. The bone plugs were inserted into the holes in the femur and secured by means of 20-mm-long screws (either 7- or 9-mm diameter). The bone plugs were then pulled out using a tensile testing machine and the pullout force was measured. The results suggest that a 7-mm (or a 9-mm) diameter screw can be used for gaps of 1 and 2 mm, and a 9-mm diameter screw should be used for gaps of 3 and 4 mm.

Spontaneous fractures of the humerus during pitching. A series of 12 cases.

We report the recent occurrence of spontaneous hu meral shaft fractures in 12 pitchers. The subjects were interviewed over the telephone using a standard ques tionnaire. Radiographs and medical records were solic ited from their physicians. Their average age was 36 years and they had pitched an average of 11.4 years with an average layoff of 14 years (range, 7 to 24). Mean time between games pitched was 21 days (range, 3 to 56). The average number of pitches before the fracture occurred was 38 (range, 10 to 100). Pain was experienced at some point before the fracture in 75% of the pitchers and 75% of the fractures were spiral. These fractures were most probably spontaneous fractures brought on by accumulated fatigue damage. The period of buildup after a prolonged period of layoff was probably insufficient time for proper bone remod eling to occur in these men. While a large percentage of these men had pain before their injury, suggesting a predisposing stress fracture, there is no doubt that their fractures could still be caused by a sudden torsional load without the presence of a stress fracture.

Instrumented Examination of Anterior Cruciate Ligament Injuries: Minimizing Flaws of the Manual Clinical Examination

The clinical examination is a basic language of orthopaedics; it is how orthopaedic surgeons communicate with one another. However, each surgeon speaks a different dialect that has been influenced by where and with whom that surgeon trained, as well as that persons own experiences. Because of the inherent variability in the magnitude, direction, and rate of force application during the clinical examination, manual arthrometers were developed in an attempt to more consistently quantify the clinical examination. Instrumented manual devices, such as the KT-1000 (MEDmetric, San Diego, CA), were the first to provide objective numbers to surgeons and researchers evaluating anteroposterior (AP) knee joint laxity. Although these devices provide surgeons with feedback related to the amount of force applied, the rate at which the force is applied is uncontrolled, resulting in a lack of reliability similar to that of the clinical examination itself. In addition to potential errors in measuring AP laxity, rotational laxity has proven to be very difficult to quantify. Robotic systems that make use of computer-driven motors to perform laxity testing have recently been developed to control the magnitude, direction, and rate of force application and thus improve the accuracy and reliability of both AP and rotational laxity evaluation. This review discusses the evolution of instrumented clinical knee examination over the past 3 decades and highlights the advantages and disadvantages of the various testing systems, as well as how current and future developments in this area may improve the field of orthopaedics by minimizing the flaws of the manual clinical examination.

The Role of Glenohumeral Capsular Ligaments in Internal and External Rotation of the Humerus

The purpose of this study was to define the relationship between internal and external rotation of the humerus and the lengths of the anterior and posterior compo nents of the glenohumeral capsuloligamentous com plex. Six cadaveric shoulders (with intact ligaments and humeri) were stripped of all muscles. Each shoulder was mounted in its correct anatomic position. The ex tent of internal and external rotation of the humerus was then measured 36 times (at 10° intervals in a 360° hu meral cone of motion). One component of the gleno humeral capsuloligamentous complex was lengthened, and the humeral rotation was again measured 36 times. The process of lengthening was done by cutting the ligament and replacing it with a beaded chain and catches sutured across the joint. The process of length ening each component was repeated in 12 combina tions, each with a different anterior and posterior com ponent length. Humeral rotation was measured 36 times using a specially designed goniometer. The length of the anterior component of the glenohumeral capsuloligamentous complex most affected external humeral rotation, and the length of the posterior com ponent most affected internal humeral rotation. How ever, the lengths of both the anterior and posterior com ponents shared in limiting rotation at a number of positions.

A Robotic System for Measuring the Relative Motion Between the Femur and the Tibia

The goal of the robotic system for measuring the relative motion between the femur and the tibia is to provide the clinician with objective parameters (numbers and graphs) which correlate with specific injuries in the knee. In this chapter the sequence of events that shaped the evolution of the robotic system is described. Several key issues that were encountered during the years of development of the robotic system are discussed, as are sources of error during biomechanical knee testing. Detail is given on the problems associated with the management of error using the robotic system. Finally, clinical examples of using the robotic system to examine two patients are presented. On balance, the robotic system allows for the reliable recording of objective parameters of the injured knee while minimizing error. The objective results obtained using the robotic system can provide the clinician with information that will allow for the best treatment plan for the patient with an injured knee.

How to Predict Knee Kinematics During an ACL Injury

The factors that ultimately lead to an anterior cruciate ligament (ACL) injury are complex. The type of sports activity, population segment, posture, bone morphology, and the internal biomechanics of the knee each play a role in risk of injury. A multitude of studies have been performed in these individual areas, which have provided information to form a prediction algorithm for ACL injury. Sports activities, such as soccer, that place a premium on jumping and landing appear to have an increased incidence of these injuries. Female athletes appear to be at a higher risk, potentially due to differences in lower extremity shape or motion patterns. Bone morphology may contribute to the likelihood of ACL injury (i.e., posterior slope and relative tibial size), and the dimensions of the “joint play envelope” may help determine the amount of force necessary to cause injury. While there is no absolute consensus on the biomechanical mechanisms leading to non-contact ACL injury, there is extensive evidence to indicate that ACL injury results from a combination of these factors. Clinicians should consider these factors when mapping out a safe return to play for sports such as soccer. Those athletes more at risk for injury may benefit from more intensive or specific physical training.