Steven B. Zelicof

Five-Year Comparative Study of Highly Cross-Linked (Crossfire) and Traditional Polyethylene

The purpose of this study was to compare the linear penetration rates of a highly cross-linked ultra-high-molecular-weight polyethylene to traditional polyethylene. Twenty-seven highly cross-linked components were matched to 27 traditional polyethylene components with respect to age, sex, body mass index, and activity level. Each group was followed up for a mean of approximately 6 years. Linear penetration was measured using Martells computerized technique (J Bone Joint Surg Am 1997;79:1635). The mean total penetration was 0.283 mm (SD, 0.253) for the highly cross-linked group. The mean total penetration for the traditional polyethylene was 0.696 mm (SD, 0.402). This difference was highly significant (P < or = .001). Our experience demonstrates a 59% reduction in total penetration of highly cross-linked polyethylene when compared with traditional polyethylene at a minimum of 5 years.

Gluteus medius strengthening and the use of the Donatelli Drop Leg Test in the athlete

OBJECTIVES To evaluate and strengthen the posterior segment of the gluteus medius. DESIGN A technical description of a novel examination and rehabilitation protocol. SETTING The gluteus medius, primarily a hip abductor, serves several important functions in the athlete. Weakness of the gluteus medius has been linked to injuries in the shoulder and iliotibial band, as well as ankle instability. Though previously treated as a homogenous muscle, recent studies of the gluteus medius show three segments with distinct function and activation - the anterior, middle, and posterior. Current rehabilitation protocol focuses primarily on the anterior and middle segments, neglecting the posterior. CONCLUSION We propose a three-stage protocol for strengthening and rehabilitation of the injured athlete and the Drop Leg Test, which can be used to identify weakness in the posterior segment of the gluteus medius.

Functional Outcomes in High-function-demand Patients After Total Knee Arthroplasty

Total knee arthroplasty is a safe last-resort treatment for osteoarthritis that has excellent results in low-function-demand elderly patients. Current implants offer the same results in high-function-demand patients. However, supportive data do not exist.One-year Krackow Activity Scores (KAS) of 552 patients from 2 prospective studies were used to retrospectively determine low- and high-function-demand populations. Low function demand was defined as a KAS between 1 and 9 points, and high function demand was defined as a KAS between 10 and 18 points. Patients were assessed preoperatively and at 6 weeks, 3 months, and 1 and 2 years postoperatively per the Knee Society Score-function domain, KAS, SF-36, range of motion, and pain. Comparability between groups was tested for demographics and comorbidities.Both groups showed significant improvement in function, range of motion, and pain 2 years postoperatively. High-function-demand patients had comparable improvement in function compared with low-function-demand patients. Excellent function can be achieved in high-function-demand patients.

Quantifying the Relationship Between the Transverse Acetabular Ligament and the Radiographic Teardrop

BACKGROUND The transverse acetabular ligament (TAL) has been described as an anatomic landmark to guide in the positioning of the acetabular component during total hip arthroplasty. On plain films, the radiographic teardrop (RT) has similarly been used as a measure of appropriate cup positioning. The goal of this study is to quantify the distance and location between the anatomic TAL and RT landmarks to aid in the positioning of acetabular component. METHODS Sixteen randomly selected cadaveric pelvises (eight males, eight females) underwent dissection. Radiographic markers were placed bilaterally at the anteromedial insertions of the TAL, and true anteroposterior pelvic radiographs of the cadavers were obtained. Distances between the markers and the lateral borders of the RT were measured. RESULTS The mean distance between the anteromedial insertion of the TAL and the lateral border of the RT in the male specimens was 11.8 (99% confidence interval, 11.4-12.2) mm. In the female specimens, the TAL to RT distance was shorter, with a mean of 8.4 (99% CI, 7.2-9.6) mm. There was a statistically significant difference between male and female cadavers (P < .01). CONCLUSION The distance between the RT and TAL differs between males and females. Understanding the distance between these anatomic and radiographic landmarks should aid surgeons in obtaining a more accurate degree of acetabular component medialization and can serve as a guide to minimize overmedialization in order to achieve more accurate and reproducible placement of acetabular components during a total hip arthroplasty.

The Tibial Sulcus as a Reference Point for Total Knee Arthroplasty

Determining the amount of tibial resection is an important aspect of knee arthroplasty. The tibial sulcus is a reference point that should be unaffected by degenerative processes. This study compared the tibial sulcus and plateau height for 50 arthritic knees to 50 normal knees on magnetic resonance imaging. The tibial sulcus measured 17.09 mm in arthritic knees and 17.88 mm in normal knees. Sulcus height differences were not statistically significant. Based on these findings, a tibial cut 12 to 14 mm from the sulcus is recommended as a reference point in arthritic knees. This measuring technique has application in limited incision knee arthroplasty.

The natural history of clinically occult avascular necrosis in systemic lupus erythematosus

Patients with systemic lupus erythematosns (SLE) are at an increased risk of developing avascular necrosis (AVN) of bone. To study the epidemiology and natural history of these clinically occult lesions, we have prospectively evaluated 68 SLE patients. All patients had been maintained on a minimum of five rag/day of Prednisone for at least six months and none had hip symptomatology. A modified MRI of both hips was performed on each patiem. A complete MR1 evaluating class and percentage of femoral head involvement, AP and lateral pfain film xrays, bone scan and physical exam were performed for each patient with a positive MR1. Repeat MRI s were obtained at three month intervals to assess possible progression or resolution. Eleven asymptomatic hips (8%) in eight patients had MRI documented AVN. These patients were followed on a yearly basis. The percentage of femoral head involvement ranged from 1-46%. One lesion was MRI class B., the remaining lesions were class A. The radiographic stage of ten hips was stage 0, the MRI class B hip was stage 1. Risk factors for dinicany occult AVN included Afro-American origin, Raynands phenomenon, migraine headaches, t oba c c o use a n d a m a x i m a l co r t i cos t e ro id dose of at least 30 rag/day. Examination and MRI follow-up of all patients with positive MR1 findings at 3 years continues to show no progression of AVN. Additionally, all patients have remained asymptomatic.