Aspartic acid racemization reveals a high turnover state in knee compared with hip osteoarthritic cartilage.

OBJECTIVE: We investigated tissue turnover in healthy and osteoarthritic cartilage. We challenge long held views that osteoarthritis (OA) is dominated by a similar turnover process in all joints and present evidence that hip and knee cartilage respond very differently to OA. METHODS: d- and l-Aspartate (Asp) were quantified for whole cartilage, collagen and non-collagenous components of cartilage obtained at the time of joint replacement. We computed the Asp racemization ratio (Asp-RR = d/d + l Asp), reflecting the proportion of old to total protein, for each component. RESULTS: Compared with hip OA, knee OA collagen fibrils (P < 0.0001), collagen (P = 0.007), and non-collagenous proteins (P = 0.0003) had significantly lower age-adjusted mean Asp-RRs consistent with elevated protein synthesis in knee OA. Knee OA collagen had a mean hydroxyproline/proline (H/P) ratio of 1.2 consistent with the presence of type III collagen whereas hip OA collagen had a mean H/P ratio of 0.99 consistent with type II collagen. Based on Asp-RR, the relative age was significantly different in knee and hip OA (P < 0.0005); on average OA knees were estimated to be 30 yrs 'younger', and OA hips 10 yrs 'older' than non-OA. CONCLUSIONS: The metabolic response to OA was strikingly different by joint site. Knee OA cartilage evinced an anabolic response that appeared to be absent in hip OA cartilage. These results challenge the long held view that OA cartilage is capable of only minimal repair and that collagen loss is irreversible.

Viability and apoptosis of human chondrocytes in osteochondral fragments following joint trauma.

Post-traumatic arthritis is a frequent consequence of articular fracture. The mechanisms leading to its development after such injuries have not been clearly delineated. A potential contributing factor is decreased viability of the articular chondrocytes. The object of this study was to characterise the regional variation in the viability of chondrocytes following joint trauma. A total of 29 osteochondral fragments from traumatic injuries to joints that could not be used in articular reconstruction were analysed for cell viability using the fluorescence live/dead assay and for apoptosis employing the TUNEL assay, and compared with cadaver control fragments. Chondrocyte death and apoptosis were significantly greater along the edge of the fracture and in the superficial zone of the osteochondral fragments. The middle and deep zones demonstrated significantly higher viability of the chondrocytes. These findings indicate the presence of both necrotic and apoptotic chondrocytes after joint injury and may provide further insight into the role of chondrocyte death in post-traumatic arthritis.

Comparative strength of three methods of fixation of transverse acetabular fractures.

With the advent of percutaneously placed lag screws for fixation of acetabular fractures, this study evaluated the strength of lag screw fixation compared with traditional fixation techniques of transverse acetabular fractures. Ten formalin-treated human, cadaveric pelvic specimens with bilateral, transtectal transverse acetabular fractures were used for this study. The right acetabular fractures were fixed with a five-hole plate and four screws with the central hole spanning the posterior fracture site. The left acetabular fractures were fixed with two lag screws, one each in the anterior and posterior columns, or with a screw and wire construct stabilizing both columns. The specimens were loaded to implant failure. Stiffness, yield strength, maximum load at failure, and site of failure was recorded. The plate and screw construct showed significantly greater yield and maximum strength when compared with the two lag screws. The stiffness of the lag screw method was 39% higher than that of the plating method, but this result was not statistically significant. In addition, the plate and screw method provided significantly greater maximum strength than the screw and wire technique. The quadrilateral plate seemed to be the weakest area of fixation because 83% of the implant failures occurred in this region. In patients in whom the risks of formal open reduction and internal fixation of acetabular fractures outweigh the possible benefits, such as in patients with burns or degloved skin, the advent of computer-assisted and fluoroscopically guided percutaneous surgical techniques have been instrumental. This study showed there is greater strength of fixation with a plate and screw construct, possibly secondary to supplementary fixation distal to the quadrilateral plate. However, lag screw fixation provided relatively greater stiffness, which may account for its clinical success. Percutaneous lag screw fixation of appropriate transverse acetabular fractures is a viable option.

Closed reduction of a dislocation of a constrained acetabular component.

A constrained acetabular liner occasionally is used in management of chronic instability after total hip arthroplasty. If dislocation occurs out of a constrained liner, open reduction is indicated. A case is presented of closed reduction of a femoral component into a constrained liner.

Tumor-induced osteomalacia and symptomatic looser zones secondary to mesenchymal chondrosarcoma.

Tumor-induced osteomalacia is a rare clinical entity that is associated with soft-tissue or skeletal tumors. We present a case report of a patient with a chest wall mesenchymal chondrosarcoma who presented with bone pain. The patient had skeletal changes in the femoral neck and fibula consistent with osteomalacia and laboratory values suggesting phosphate diabetes. The patient was treated with tumor resection and phosphate supplementation with reversal of the signs and symptoms of osteomalacia. Tumor-induced osteomalacia is vitamin-D-resistant and often reversed by complete removal of the tumor. Most commonly, the causative tumors are of vascular, mesenchymal, or fibrous origin. The osteomalacia is associated with bone pain, muscle weakness, and radiographic changes. Tumor-induced humoral factors have been implicated in causing the osteomalacia, but the definite etiology has yet to be determined. Current treatment includes complete tumor resection and electrolyte supplementation.

A new hazard of cornstarch, an absorbable dusting powder.

Cornstarch is currently the only powder used in the manufacture of surgical and examination gloves. The purpose of this study was to determine if cornstarch damages local tissue defenses in contaminated wounds. It was found that in contaminated wounds, cornstarch enhanced the growth of bacteria and elicited exaggerated inflammatory responses as measured by wound induration. As a result of this investigation, we do not recommend the use of gloves with cornstarch powders.

New advances in electronic devices for hole detection.

Holes in surgical gloves are considered to be an important source of transmission of pathogens between surgeon and patient. Two new glove hole detectors have been devised to alert the surgeon to the presence of holes. These devices have been evaluated using six powder-free and seven powdered varieties of surgical gloves that were either dry or exposed to hydration. Eight of the 13 surgical gloves hydrated rapidly with water, altering their resistance to the conduction of electricity. Because the Barrier Integrity Monitor¿ only has a hydration monitor, 68 false positives occurred during the evaluation, indicating to the surgeon that he/she should change gloves unnecessarily because the glove had no hole. In contrast, the Surgic Alert Monitor¿ (SAM¿) had a hydration alarm as well as a glove hole detection alarm. During the 104 tests, the SAM¿ device showed no false positives. In the testing of five of the rapidly hydrating types of surgical gloves, the SAM¿ device could not reliably detect holes. On the basis of this study, the SAM¿ device, in conjunction with gloves that resist hydration, appeared to be a reliable hole detection monitor.

Personal emergency response systems.

A personal response system is a signaling device that summons help during an emergency. Although personal response systems vary widely, there are three components. The first component is the electronic hardware in the home, which consists of portable and installed sensors and the control console. The second component is the emergency response center, which is either provider-based or manufacturer-based. The third component involves the dispatch of appropriate assistance. The primary users of personal response systems are women in their seventies and eighties who live alone and who have cardiac and musculoskeletal problems, which make them prone to falls. The frequency of personal response system use varies from an average of 0.44 to 0.84 emergencies per subscriber per year. Program coordinators believe that personal response systems help to delay institutionalization, reduce admissions to hospitals, substantially shorten hospital stays, and reduce the duration of home attendant services. The most favorable impact of the personal response system has been its psychologic value to the users and their families.

A system for adaptive transportation.

In our society, we take for granted the ability to travel with few restrictions. For most travelers, the major factor that limits travel is cost. However, for a significant number of Americans, the phrase "freedom to travel" is meaningless. These are the physically handicapped, a group with special needs that has long been denied what every American assumes to be a natural right.

Is there a need for state health department sanitary codes for public hydrotherapy and swimming pools?

The Board of Health of the Commonwealth of Virginia has an outdated sanitary code for its public hydrotherapy and swimming pools. The code is restricted to pools in hotels and other lodging places. The absence of modern regulations for public hydrotherapy and swimming pools has permitted serious deficiencies in pool maintenance, which are highlighted in this report. The most notable of these deficiencies was the presence of high levels of bacterial contamination that could predispose to infect in the water of one public hot tub. The results of this study indicate that the Virginia Board of Health sanitary code for pool water must be revised immediately and should include all public hydrotherapy and swimming pools. Other states and communities may want to assess their codes for swimming pools and hydrotherapy tubs to avoid deficiencies that could be detrimental to public health.

Automated hydrotherapy pool water treatment system.

An automated hydrotherapy water treatment system was described that controls chemical pumps that maintain the pool's water pH and chlorine levels at the designated set points, regardless of the bather load. This system consists of sensing electrodes, a controller, and positive displacement pumps. Because outbreaks of waterborne infections have never been reported in facilities in which the pool water has been continuously maintained at pH 7.2 to 7.8 with a free available chlorine level of at least 1.0 ppm, we recommend that this type of water treatment system be installed in all public pools.