➤ Although multiple theories have been proposed, no one pathophysiologic mechanism has been identified as the etiology for the development of osteonecrosis of the femoral head. However, the basic mechanism involves impaired circulation to a specific area that ultimately becomes necrotic.➤ A variety of nonoperative treatment regimens have been evaluated for the treatment of precollapse disease, with varying success. Prospective, multicenter, randomized trials are needed to evaluate the efficacy of these regimens in altering the natural history of the disease.➤ Joint-preserving procedures are indicated in the treatment of precollapse disease, with several studies showing successful outcomes at mid-term and long-term follow-up.➤ Studies of total joint arthroplasty, once femoral head collapse is present, have described excellent outcomes at greater than ten years of follow-up, which is a major advance and has led to a paradigm shift in treating these patients.➤ The results of hemiresurfacing and total resurfacing arthroplasty have been suboptimal, and these procedures have restricted indications in patients with osteonecrosis of the femoral head.

Nontraumatic Osteonecrosis of the Femoral Head: Where Do We Stand Today?: A 5-Year Update

Anterior hip or groin pain is a common complaint for which people are referred for physical therapy, with the hip region being involved in approximately 5% to 9% of injuries in high school athletes.1 Although anterior hip pain is known to result from a number of musculoskeletal and systemic pathologies, a tear of the acetabular labrum is a recent addition to the list that is of particular interest to physical therapists. This mechanically induced pathology is thought to result from excessive forces at the hip joint2,3 and has been proposed as part of a continuum of hip joint disease that may result in articular cartilage degeneration.2 Although the number of recent articles in the orthopedic literature identifying acetabular labral tears as a source of hip pain is increasing, labral tears often evade detection, resulting in a long duration of symptoms, greater than 2 years on average, before diagnosis.4–8 Studies have shown that 22% of athletes with groin pain9 and 55% of patients with mechanical hip pain of unknown etiology2 were found to have a labral tear upon further evaluation. In order to provide the most appropriate intervention for patients with anterior hip or groin pain, physical therapists should be knowledgeable about all of the possible sources and causes of this pain, including a tear of the acetabular labrum and the possible factors contributing to these tears. Therefore, the purpose of this article is to review the anatomy and function of the acetabular labrum and present current concepts on the etiology, clinical characteristics, diagnosis, and treatment of labral tears.

The acetabular labrum is a ring consisting of both fibrocartilage and dense connective tissue10 attached to the bony rim of the acetabulum (Fig. 1). This ring is normally triangular in cross …

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Acetabular Labral Tears

The hip labrum has many functions, including shock absorption, joint lubrication, pressure distribution, and aiding in stability, with damage to the labrum associated with osteoarthritis. The etiology of labral tears includes trauma, femoroacetabular impingement (FAI), capsular laxity/hip hypermobility, dysplasia, and degeneration. Labral tears present with anterior hip or groin pain, and less commonly buttock pain. Frequently, there are also mechanical symptoms including clicking, locking, and giving way. The most consistent physical examination finding is a positive anterior hip impingement test. Because of the vast differential diagnosis and the need for specialized diagnostic tools, labral tears frequently go undiagnosed during an extended period of time. Evaluation usually begins with plain radiographs to assess for dysplasia, degeneration, and other causes of pain. While magnetic resonance imaging (MRI) and computed tomography scans are unreliable for diagnosis, magnetic resonance arthrography (MRA) is the diagnostic test of choice, with arthroscopy being the gold standard. Typically, treatment begins conservatively with relative rest and non-steroid anti-inflammatory agents, with physical therapy (PT) being controversial. Often, surgical treatment is necessary, which entails, arthroscopic debridement of labral tears and surgical repair of associated structural problems.

/pdf/a-comprehensive-review-of-hip-labral-tears-4ndav9031s.pdf

A comprehensive review of hip labral tears

Advances in metals and alloys for joint replacement

The elderly population has substantially increased worldwide. Aging is a complex process, and the effects of aging are myriad and insidious, leading to progressive deterioration of various organs, including the skeleton. Age-related bone loss and resultant osteoporosis in the elderly population increase the risk for fractures and morbidity. Osteoporosis is one of the most common conditions associated with aging, and age is an independent risk factor for osteoporotic fractures. With the development of noninvasive imaging techniques such as computed tomography (CT), micro-CT, and high resolution peripheral quantitative CT (HR-pQCT), imaging of the bone architecture provides important information about age-related changes in bone microstructure and estimates of bone strength. In the past two decades, studies of human specimens using imaging techniques have revealed decreased bone strength in older adults compared with younger adults. The present paper addresses recently studied age-related changes in trabecular and cortical bone microstructure based primarily on HR-pQCT and micro-CT. We specifically focus on the three-dimensional microstructure of the vertebrae, femoral neck, and distal radius, which are common osteoporotic fracture sites.

/pdf/age-related-changes-in-trabecular-and-cortical-bone-3sy7lnoskr.pdf

Age-related changes in trabecular and cortical bone microstructure.

A systematic review was conducted to answer the following questions: (1) Does kinematically aligned (KA) total knee arthroplasty (TKA) achieve clinical outcomes comparable to those of mechanically aligned (MA) TKA? (2) How do the limb, knee, and component alignments differ between KA and MA TKA? (3) How is joint line orientation angle (JLOA) changed from the native knee in KA TKA compared to that in MA TKA? Nine full-text articles in English that reported the clinical and radiological outcomes of KA TKA were included. Five studies had a control group of patients who underwent MA TKA. Data on patient demographics, clinical scores, and radiological results were extracted. There were two level I, one level II, three level III, and three level IV studies. Six of the nine studies used patient-specific instrumentation, one study used computer navigation, and two studies used manual instrumentation. The clinical outcomes of KA TKA were comparable or superior to those of MA TKA with a minimum 2-year follow-up. Limb and knee alignment in KA TKA was similar to those in MA TKA, and component alignment showed slightly more varus in the tibial component and slightly more valgus in the femoral component. The JLOA in KA TKA was relatively parallel to the floor compared to that in the native knee and not oblique (medial side up and lateral side down) compared to that in MA TKA. The implant survivorship and complication rate of the KA TKA were similar to those of the MA TKA. Similar or better clinical outcomes were produced by using a KA TKA at early-term follow-up and the component alignment differed from that of MA TKA. KA TKA seemed to restore function without catastrophic failure regardless of the alignment category up to midterm follow-up. The JLOA in KA TKA was relatively parallel to the floor similar to the native knee compared to that in MA TKA. The present review of nine published studies suggests that relatively new kinematic alignment is an acceptable and alternative alignment to mechanical alignment, which is better understood. Further validation of these findings requires more randomized clinical trials with longer follow-up. Level II.

Kinematic alignment is a possible alternative to mechanical alignment in total knee arthroplasty

Sixty-four hips in 62 patients were revised with a Mueller ring (28 hips), Ganz ring (18 hips), and Burch-Schneider cage (18 hips) under the direction of a single surgeon. A polyethylene cup was cemented into the metal support of all hips. Average follow-up was 4.6 years (range, 2.0-6.7 years). Six rings were revised because of aseptic loosening, and 5 others were radiographically loose, for a mechanical failure rate of 11 of 64 (17%). Acetabular metal ring supports failed by migration when defects of > or =60% of the superior weight-bearing bone were filled by only cement or particulate graft. At the time of surgery, the superior rim of the metal support should be against host-bone for 60% of its support, and if not, the use of bulk allograft, rather than particulate graft, is required. Dislocation was the second failure mechanism identified, and this occurred in 15 hips (23%), with reoperation required in 5 hips (8%). A constrained liner should be used in patients with nonunion of the trochanter and preoperative abductor weakness that grades fair/minus or worse as measured by the side-lying abduction test.

Technical factors for success with metal ring acetabular reconstruction.

Purpose
The joint line of the native knee is horizontal to the floor and perpendicular to the vertical weight-bearing axis of the patient in a bipedal stance. The purposes of this study were as follows: (1) to find out the distribution of the native joint line in a population of normal patients with normal knees; (2) to compare the native joint line orientation between patients receiving conventional mechanically aligned total knee arthroplasty (TKA), navigated mechanically aligned TKA, and kinematically aligned TKA; and (3) to determine which of the three TKA methods aligns the postoperative knee joint perpendicular to the weight-bearing axis of the limb in bipedal stance.

Kinematically aligned TKA can align knee joint line to horizontal

This study investigated the three dimensional (3D) trabecular microstructure of the alveolar and basal bone in the mandible using micro-CT and compared the morphometric values of the different sites. Ten specimens were prepared and scanned using a micro-CT system. Both the alveolar and basal trabecular bone of the premolar region in the mandible were measured for the structural analysis. Cross-sectional 1024x1024 pixel images were created. From the two-dimensional (2D) images produced, 3D structural images were reconstructed. After scanning the specimen, the volumes of interest (VOI) of the alveolar and basal bone regions were selected from the 3D reconstruction images, and the structural parameters such as bone volume fraction, bone surface density, trabecular thickness, trabecular separation, trabecular number and structural model index were analyzed. The trabecular structure showed a marked variation within the sites of the specimen, especially in the basal trabecular bone inferior to the mandibular canal. In both the alveolar and basal bone regions, a mixture of both plate-like and rod-like structures was observed. The alveolar region showed a more compact, plate-type trabecular structure than the basal regions. In parametric comparison with the basal bone, the alveolar bone generally had a higher bone volume fraction, bone trabecular thickness and trabecular number, and lower bone surface density, trabecular separation and structural model index. The alveolar bone consisted of a compact bone structure with a large amount of thick plate-type trabecular bone, which was effectively resistant to the masticatory forces. As the measurements were made closer to the basal bone, a loose structure was observed with lower bone volume and fewer, thin, rod-like trabeculae.

The three-dimensional microstructure of the trabecular bone in the mandible

We report a case of ceramic liner fracture in a 34-year-old man that occurred 1 year 9 months after total hip arthroplasty with a BiCONTACT (Aesculap, Tuttlingen, Germany) ceramic-on-ceramic prosthesis. The ceramic liner was found within the metal shell in 4 large pieces and multiple small fragments in the peripheral portions. Its condition indicated that the possible mechanism of late ceramic liner chip fracture was repeated episodes of impingement between the prosthetic neck and the edge of the ceramic liner. Squatting, kneeling, and sitting cross-legged caused impingement. These positions are more common in Asian populations than in Western populations. After the joint was thoroughly irrigated, a new modular ceramic liner and a 28-mm ceramic head were implanted.

Ye-Yeon Won

Papers

Kinematic alignment is a possible alternative to mechanical alignment in total knee arthroplasty

Technical factors for success with metal ring acetabular reconstruction.

Kinematically aligned TKA can align knee joint line to horizontal

The three-dimensional microstructure of the trabecular bone in the mandible

Delayed fracture of a ceramic insert with modern ceramic total hip replacement.