Levels of carbon dioxide in helmet systems used during orthopaedic operations

The use of isolation helmets has gained popularity as a method of possible protection of the operating-room personnel from diseases that can be transmitted during operative procedures. However, the use of these systems has been associated with a variety of symptoms, including fatigue, diaphoresis, nausea, headache, and irritability. These symptoms have often been attributed to the mental stress of the operative procedure or the physical discomfort of the helmet. As far as we know, no manufacturers include the measured levels of carbon dioxide or the rate of air exchange of their helmet system. A possible common cause of discomfort with helmet systems is the level of carbon dioxide to which the person wearing the device is exposed. We measured the levels of carbon dioxide in four helmet systems from three different manufacturers during light exercise designed to approximate the exertion during an orthopaedic operation. All but one unit failed to meet the exposure limits recommended by the National Institute for Occupational Safety and Health and the Occupational Safety and Health Administration regarding exposure to carbon dioxide. One unit, the Stackhouse Freedom Aire self-contained system, did meet these standards, but the levels of carbon dioxide in this helmet were more than 1000 per cent greater than the ambient levels in air (440 parts per million compared with 4939 parts per million). Isolation systems must be evaluated carefully not only for comfort but also for the physiological effects caused by exposure to elevated levels of carbon dioxide. Operating-room personnel who use such systems should be aware that many of the physical symptoms that they experience may be associated with elevated levels of carbon dioxide.

Arthroscopic repair of meniscal tears that extend into the avascular zone. A review of 198 single and complex tears

We assessed the results of 198 meniscal tears that had a major segment in the central avascular region repaired with an arthroscopically assisted inside-out technique. There were 177 patients whose mean age was 28 years. Eighty-two percent were injured during sports, and 71% also required anterior cruciate ligament reconstruction. The menisci were evaluated by clinical examination (180 repairs) a mean of 42 months postoperatively, by follow-up arthroscopic evaluation (91 repairs) a mean of 18 months postoperatively, or both. At followup, 159 (80%) of the 198 tears were asymptomatic for tibiofemoral joint symptoms, and 39 (20%) required repeat arthroscopic surgery for these symptoms. Of the 91 repairs evaluated arthroscopically, 23 (25%) were classified as healed, 35 (38%) as partially healed, and 33 (36%) as failed. We recommend repair of meniscal tears that extend into the avascular region for select patients, including those in their 20s and 30s and highly competitive athletes. This study's reoperation rate of 20% should not be interpreted as the rate of meniscal healing, but as the incidence of tibiofemoral joint symptoms. Even though this is a higher rate than that reported for the repair of peripheral meniscal tears, we believe the benefits of a potentially functional meniscus outweigh the risks of reoperation.

Proximal dissection of a popliteal giant synovial cyst: a case report

Giant synovial cysts in patients with rheumatoid arthritis are well-recognized soft-tissue masses adjacent to the knee. Cases involving the elbow, hip, and other synovial joints have been reported as well. Regardless of location, these expanding, space-occupying lesions usually present with nonspecific symptoms of swelling and pain. Less commonly, the original presentation may be related to the secondary effects of the cyst on nearby anatomic structures. We present a case of a giant synovial cyst originating posteriorly in the knee, which, rather than dissecting distally into the calf, dissected proximally into the posterior soft tissue of the thigh in a patient with long-standing rheumatoid arthritis.

Technical considerations in the management of complex meniscus tears

Meniscal repair continues to be an important procedure in patients with meniscal tears. The orthopedic literature has recommended excision of complex tears or tears that are located in the central avascular region. For the past 13 years, the authors have repaired all meniscal tears that can be reduced anatomically and that have healthy tissue that will support the multiple sutures required for a stable repair, regardless of tear pattern or location. Correct patient selection criteria continue to be important. In all cases, the risks of complications and retear must be considered carefully and judged against the potential benefits of repair. A postoperative rehabilitation program that allows early range of motion, and progression of weight bearing is not detrimental to the healing process if the repair is stable. Close postoperative follow-up examinations are necessary to determine the incidence of meniscal symptoms; however, the absence of joint line pain, catching, locking, or effusion does not guarantee complete healing of the tear. Follow-up arthroscopy is currently the most accurate method to determine if complete or partial healing has occurred.

A rapid method for emergency ring removal

Injuries caused by embedded rings are extremely rare. Swelling can lead to decreased circulation and can threaten the viability of involved fingers. Skin changes can become chronic, as when rings are left on fingers of patients with decreased mentation or sensation. In this report, the authors discuss a technique for removal of embedded rings from the fingers of a schizophrenic patient.

Postmortem comparative analysis of titanium and hydroxyapatite porous-coated femoral implants retrieved from the same patient. A case study

The results of bilateral postmortem analysis of titanium and plasma-sprayed hydroxyapatite (HA) porous-coated femoral components of the same Anatomic Porous Replacement design retrieved from a 35-year-old female donor are reported. Analysis was conducted using backscattered electron imaging, histology, and radiographic techniques. The appositional bone index, percent bone ingrowth, and mineral content were measured for both implants. The results showed a 177% higher appositional bone index (P = .014) for the HA porous-coated Anatomic Porous Replacement component compared to the titanium Anatomic Porous Replacement component. Backscattered electron analysis showed 50% more bone in the HA porous-coated implant (P = .028). The mineral content analysis demonstrated that the bone ingrown into the HA porous-coated device was 23% less mineralized (P = .016). The data from this case study suggested that plasma-sprayed HA porous-coated implants may assist in increasing the amount of bone ingrowth and skeletal attachment in total hip arthroplasties.

Microscopic analysis of autograft bone applied at the interface of porous-coated devices in human cancellous bone

This study describes the response of human cancellous bone when autologous bone chips are added at operation to the interface between host bone and porous-coated implants. During the first operation of a staged bilateral total knee arthroplasty, seven patients consented to have paired porous-coated devices implanted into their opposite medial femoral condyle. One device of each pair had autologous bone chips applied to the porous-coating, and the other was not grafted and was a control. The devices were removed en bloc at the second total knee arthroplasty 6 to 49 weeks later. Backscattered electron imaging showed significantly more bone (p < or = 0.05) in the porous-coating of the implant treated with autologous bone chips which significantly increased (p < or = 0.05) the amount of bone available at the interface. The grafted devices had a mineral apposition rate of 1.04 +/- 0.20 microns/day for the interface and 0.81 +/- 0.09 microns/day for the peripheral bone. This compared with corresponding figures of 1.03 +/- 0.38 microns/day and 0.79 +/- 0.19 microns/day at the ungrafted devices. The mineral apposition rate at the interface of the porous-coated implants was significantly increased (p < or = 0.05) relative to the host bone in the periphery. Our results support the view that autologous bone chips are effective in attaching cementless porous-coated total knee replacements to the human skeleton by bone ingrowth.

Bone ingrowth into porous-coated tibial components implanted with autograft bone chips. Analysis of ten consecutively retrieved implants

Ten asymmetric porous-coated tibial knee components were consecutively retrieved from nine patients with implantation times ranging from 1 week to 48 months. Morselized autograft bone chips were applied to the resected surface of the tibia prior to component implantation. Microradiographic analysis showed bone in contact with 64 +/- 10% of the porous-coated interface. Backscattered electron imaging of the bone-implant interface revealed bone within 8-22% of the porous coating. Although bone in the form of autograft bone chips was observed in the porous coating of the 1 and 3 week specimens, it was not connected to the host bone. By 3 and 6 months, the bone chips were integrated and connected to the host bone providing osseous continuity from the porous coating to the skeleton. This study shows that reproducible bone ingrowth into porous-coated tibial components is achievable using autograft bone chips to promote bone fixation.

Hyaluronan solution as a cartilage antidesiccant

During arthrotomy, desiccation of the articular cartilage of synovial joints by the ambient environment of the operating room causes chondrocyte death and may promote degenerative changes within the joint. This study documents the efficacy of a biomaterial, hyaluronan (HY) solution, to maintain chondrocyte viability during desiccation. Rabbit patellar articular cartilage was air-dried for 2 h with and without application of the HY solution. As assessed by 35SO4 uptake and autoradiography, the HY solution helped maintain chondrocyte viability, when compared to air dried specimens (p less than or equal to 0.02). HY solution applied to the articular surfaces of joints undergoing arthrotomy may offset the detrimental effects of desiccation, such as chondrocyte death and degenerative joint changes.

Bilateral tibial components of different cementless designs and materials. Microradiographic, backscattered imaging, and histologic analysis

Postmortem evaluation was conducted on two cementless knee prostheses considered clinically successful. The two retrieved uncemented porous-coated tibial components of different designs, and materials were evaluated by microradiography, backscattered electron (BSE) imaging, and light microscopy. The right prosthesis, in place for 25 months, was a Porous-Coated Anatomic (PCA) implant with double-layered, sintered, cobalt-chromium alloy beads. The left prosthesis was a Natural-Knee (N-K) implant with a porous coating of cancellous-structured pure titanium implanted for 19 months. A quantitative microradiographic index, the appositional bone index (ABI), was developed to indicate the probability of bone ingrowth occurring into the porous coating. The ABI is a ratio of bone in apposition with porous coating divided by the total amount of porous coating available. The PCA had an average ABI of 9%, and the N-K, 67%. BSE images of the PCA demonstrated no bone within the porous coating. BSE images of the N-K implant showed bone ingrowth into 22% of the pore volume when porous coating was in apposition to host bone. Histology of the PCA revealed fibrous connective tissue throughout the porous coating and between the porous coating-bone interface. Histology of the N-K implant revealed bone ingrowth and osteoblastic activity along the bone within the porous coating.