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Biomedical subjects

Michael A Mont

Publications and source records attributed to Michael A Mont.

At least 19 recordsLinked to original sources
PubMed2007

Gait analysis of patients with resurfacing hip arthroplasty compared with hip osteoarthritis and standard total hip arthroplasty.

Patients with standard total hip arthroplasties may have reduced hip abduction and extension moments when compared with normal nonosteoarthritic hips. In comparison, patients after resurfacing total hip arthroplasty appear to have a near-normal gait. The authors evaluated temporal-spatial parameters, hip kinematics, and kinetics in hip resurfacing patients compared with patients with unilateral osteoarthritic hips and unilateral standard total hip arthroplasties. Patients with resurfacing walked faster (average 1.26 m/s) and were comparable with normals. There were no significant differences in hip abductor and extensor moments of patients with resurfacing compared with patients in the standard hip arthroplasty group. This study showed more normal hip kinematics and functionality in resurfacing hip arthroplasty, which may be due to the large femoral head.

Adult↗
PubMed2007

Clinical experience using a minimally invasive surgical approach for total knee arthroplasty: early results of a prospective randomized study compared to a standard approach.

There has been recent attention concerning minimally invasive techniques for knee arthroplasty. It is not clear whether these complicated techniques can be reproduced across multiple centers and for all surgeons. This prospective, randomized, multicenter study was carried out to assess safety and efficacy of a minimally invasive total knee arthroplasty. The study consisted of 80 knees. There were no differences in blood loss, operative time for completion of surgery, infection, and ultimate wound healing. There were 4 knees with delayed wound healing in the minimally invasive surgical technique group versus 1 in the standard group, which did not affect outcome. Early clinical and radiographic results were also indistinguishable. At 12 weeks follow-up, there was no difference in mean Knee Society objective and functional scores. In summary, in this study, minimal incision total knee arthroplasty demonstrated no improvement over a standard approach.

Aged↗
PubMed2006

An unusual cause of knee pain 10 years after arthroscopy.

Arthroscopic surgery, although relatively minimally invasive, is associated with specific complications. Cases of instruments retained in the knee joint after arthroscopy have been reported. There have been reports of scalpel blades detaching into the joint during the approach that were immediately retrieved, with or without arthrotomy. We report the case of a scalpel blade retained in the knee joint for 10 years after arthroscopy. This case demonstrates the need for the surgeon and the whole operating room staff to be aware of the instrumentation and to systematically check the instruments at the beginning, middle, and end of the procedure. The significance of reporting this case is to make the orthopaedic community aware of possible complications that can occur even with relatively "low-risk" procedures.

Arthrography↗
PubMed2006

Surgical treatment and customized rehabilitation for stiff knee arthroplasties.

UNLABELLED: Treating patients who have arthrofibrotic or stiff knees after total knee arthroplasty can be difficult. Treatment with arthroscopic débridement, arthrolysis of adhesions with polyethylene spacer exchange, or complete revision arthroplasty often has led to less than optimal range of motion and functional outcomes. We used a combination of surgical arthrolysis and an intensive postoperative rehabilitation protocol, including functional bracing, to treat this condition. We then retrospectively reviewed 18 knees in 17 patients who had stiff knees after total knee arthroplasty with no other detectable clinical or radiographic abnormalities, at a mean followup of 30 months. Seventeen knees (94%) had gains in knee range of motion with a mean increased range of motion of 31 degrees. Although 16 of 17 patients had clinical improvement and were satisfied with the procedure, only (2/3) of the patients (12 of 18 patients) had excellent or good Knee Society objective scores. This combined surgical and rehabilitation method can lead to an increased range of motion. All patients improved clinically, but good functional results were less predictable. The authors think treatment of these difficult knees should be aimed at soft tissue operative releases supplemented by an intensive rehabilitation protocol. LEVEL OF EVIDENCE: Therapeutic study, level IV (prospective study). See Guidelines for Authors for a complete description of levels of evidence.

Adult↗
PubMed2006

Minimally invasive revision total knee arthroplasty.

UNLABELLED: Exposure in revision total knee arthroplasty can be difficult. For example, eversion of the patella may require a number of procedures including vastus snips, V-Y turndowns, and tibial tubercle osteotomies. A minimally invasive approach further adds to exposure difficulties. We report a new approach for exposure during difficult revision total knee arthroplasties. A soft tissue envelope technique allows retraction of the patella and avoids eversion. This technique reduces the size of the incision, reduces quadriceps muscle damage, and enhances exposure. It is essential that appropriate instrumentation is used along with down sized femoral and tibial cutting blocks. We report all 17 revision knee arthroplasties using this technique including unicompartmental revisions, tibial component revisions, and femoral component revisions. Followup averaged 29 months (range, 24-39 months). We had one case of posterior retained cement after a full revision with no subsequent complications. One patient required an arthroscopic lateral release for patellar maltracking. Preliminary results are encouraging using improved instrumentation we find essential for enhanced exposure. We believe this a reasonable approach for selected total knee arthroplasty revisions. LEVEL OF EVIDENCE: Therapeutic study, level IV (retrospective case series). See the Guidelines for Authors for a complete description of levels of evidence.

Aged↗
PubMed2006

Nontraumatic osteonecrosis of the femoral head: ten years later.

The etiology of osteonecrosis of the hip may have a genetic basis. The interaction between certain risk factors and a genetic predisposition may determine whether this disease will develop in a particular individual. The rationale for use of joint-sparing procedures in the treatment of this disease is based on radiographic measurements and findings with other imaging modalities. Early diagnosis and intervention prior to collapse of the femoral head is key to a successful outcome of joint-preserving procedures. The results of joint-preserving procedures are less satisfactory than the results of total hip arthroplasty for femoral heads that have already collapsed. New pharmacological measures as well as the use of growth and differentiation factors for the prevention and treatment of this disease may eventually alter our treatment approach, but it is necessary to await results of clinical research with long-term follow-up of these patients.

Arthroplasty↗
PubMed2006

Uncemented total hip arthroplasty in young adults with osteonecrosis of the femoral head: a comparative study.

BACKGROUND: The outcome of uncemented total hip arthroplasty in patients with osteonecrosis of the femoral head in general, and in young adults in particular, remains largely unknown. This study evaluated the clinical and radiographic results of uncemented total hip arthroplasty in young adults with osteonecrosis of the femoral head and compared these results to those seen in young adults with osteoarthritis. METHODS: Forty-one consecutive patients with osteonecrosis of the femoral head (fifty-two hips) and forty patients with osteoarthritis (fifty-two hips) were treated with an uncemented total hip arthroplasty at our institution. The mean age for the osteonecrosis group was thirty-eight years, and, for the osteoarthritis group, forty-two years. Clinical and radiographic outcomes at a minimum of two years were assessed. RESULTS: At a mean duration of follow-up of three years, the functional improvement was significant in both groups (p < 0.05). The outcome was good to excellent for 94% (forty-nine hips) in the osteonecrosis group and 96% (fifty hips) in the osteoarthritis group. There were two revisions in the osteonecrosis group and one revision in the osteoarthritis group. Survivorship free of revision at the time of the latest follow-up was 96.1% for the osteonecrosis group and 98% for the osteoarthritis group. CONCLUSIONS: The short-term results of cementless total hip arthroplasty in patients with osteonecrosis of the femoral head were encouraging and comparable with the results of a matched group of patients with osteoarthritis. We await further follow-up to see if these promising results hold true. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions to Authors on jbjs.org for a complete description of levels of evidence.

Adolescent↗
PubMed2006

Systematic analysis of classification systems for osteonecrosis of the femoral head.

BACKGROUND: Multiple classification systems for osteonecrosis of the hip have been developed to assist physicians in the diagnosis and treatment of this potentially debilitating disorder. The purpose of this analysis was to delineate the classification systems utilized in reports published since 1985 and, through a comparison of the most commonly used systems, to identify consistent factors that would allow for cross-publication comparisons to be made. METHODS: We performed a PubMed search for reports of outcome studies concerning treatment methods for osteonecrosis of the hip. All studies of reported outcomes with greater than ten patients were included in the analysis. Various classification systems were tabulated to determine usage frequencies. The four most commonly used systems were then analyzed to determine common factors used for classification. RESULTS: One hundred and fifty-seven studies were available for analysis. Sixteen major classification systems that made use of more than one radiographic factor were identified, and nine of these systems had one to five modifications reported throughout the literature. Additionally, eleven other systems made use of single factors obtained from either magnetic resonance imaging or anatomic data. The review revealed that four classification systems accounted for greater than 85.4% of the reported studies. Parameters for these four systems were stratified to allow for uniformity of patient or study evaluation. CONCLUSIONS: This analysis of the reported classification systems for osteonecrosis of the femoral head revealed several similarities between the most commonly used systems. An analysis of patients can be made with any of the four major systems if specific data are collected according to various magnetic resonance imaging and radiographic findings. This approach will allow for easier comparison of studies across different centers. LEVEL OF EVIDENCE: Prognostic Level III. See Instructions to Authors on jbjs.org for a complete description of levels of evidence.

Classification↗
PubMed2006

Osteonecrosis of the knee after laser or radiofrequency-assisted arthroscopy: treatment with minimally invasive knee arthroplasty.

BACKGROUND: Osteonecrosis of the knee after various arthroscopic procedures associated with the use of laser or radiofrequency devices has been described in a few case reports. The purpose of this study was to report on a series of nineteen patients with osteonecrosis of the knee after arthroscopic procedures. A literature search was done to compare this series of patients to previously reported cases. In addition, we analyzed the outcome after treatment with minimally invasive knee arthroplasty. METHODS: We studied patients who had development of osteonecrosis of the knee after a routine arthroscopic procedure. Preoperative and postoperative clinical notes, radiographs, and magnetic resonance images of patients were analyzed. Only those patients with no evidence of osteonecrosis on preoperative magnetic resonance imaging who later had development of osteonecrosis and subsequently required a knee arthroplasty were included. We conducted a search of the current literature to compare the results seen in our patient population with those seen in other patients with this entity. Patients were followed both clinically and radiographically for a mean of sixty-two months. RESULTS: A total of nineteen patients met the inclusion criteria. There were fourteen women and five men with a mean age of sixty-nine years. Six patients underwent an arthroscopy with associated holmium or yttrium-aluminum-garnet laser treatment, ten patients had associated radiofrequency treatment, and three patients had microfracture surgery. Subsequent arthroplasty procedures included four unicompartmental knee arthroplasties and fifteen tricompartmental knee arthroplasties. At the time of final follow-up, the mean Knee Society objective score was 95 points. CONCLUSIONS: Arthroscopic procedures may play a role in the development of osteonecrosis of the knee. To our knowledge, this is the largest series of patients to have development of this condition after arthroscopy with associated laser, radiofrequency, or microfracture surgery. The midterm results of knee arthroplasty in this unique patient population are comparable with those of patients undergoing knee arthroplasty for osteoarthritis of the knee. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions to Authors on jbjs.org for a complete description of levels of evidence.

Aged↗
PubMed2006

Use of metal-on-metal total hip resurfacing for the treatment of osteonecrosis of the femoral head.

BACKGROUND: Recently, with the advent of improved metal-on-metal prostheses, total hip resurfacing has emerged as a viable arthroplasty option. However, it remains controversial whether this procedure should be used in patients with osteonecrosis when the femoral resurfacing component is cemented onto dead bone. The purpose of this study was to analyze the clinical and radiographic outcomes of metal-on-metal total hip resurfacing arthroplasty in patients with osteonecrosis of the femoral head. In addition, this group was compared with a matched group of patients who were diagnosed as having osteoarthritis. METHODS: Forty-two osteonecrotic hips that were treated with a metal-on-metal total hip resurfacing arthroplasty were studied. They were matched by gender, age, prosthesis, surgeon, and surgical approach to forty-two osteoarthritic hips that were treated with the same metal-on-metal prosthesis. In the osteonecrosis group, there were twenty-five men and eleven women, and in the osteoarthritis group, there were twenty-eight men and thirteen women. The mean age at the time of surgery was forty-two years. Patients were followed both clinically and radiographically for a mean of forty-one months. RESULTS: The clinical outcomes were similar for both groups, with a good or excellent outcome in thirty-nine hips (93%) with osteonecrosis and a good or excellent outcome in forty-one hips (98%) with osteoarthritis. In each of the two groups, there were two failures that required conversion to a standard total hip arthroplasty. Survivorship curves were similar for the two patient groups. CONCLUSIONS: The short-term results for metal-on-metal total hip resurfacing for this challenging patient population with osteonecrosis were excellent and comparable with those seen in patients with osteoarthritis. We await long-term results to see if these early results are maintained. LEVEL OF EVIDENCE: Prognostic Level II. See Instructions to Authors on jbjs.org for a complete description of levels of evidence.

Adolescent↗
PubMed2006

Sports activity after total hip and knee arthroplasty : specific recommendations concerning tennis.

Lower extremity total joint arthroplasties are among the most successful operations in orthopaedics. Presently, it appears that some patients wish to not only have general functions restored, but also desire the opportunity to return or continue on a high level of activity. This review summarises the literature concerning athletic activity, and tennis in particular, in relation to lower extremity total joint arthroplasties. Orthopaedic surgeons frequently recommend participation in low-impact sports such as swimming, walking, bicycling, bowling and golf. The patient's return to these recreational activities appears to be without problems. In contrast, there has been a general consensus from surgeons to avoid high-impact sports such as tennis and jogging after total joint arthroplasty, but there have been numerous studies that reported functional results being compatible with these activity levels. Conflicts emerge with some studies that describe lower survival rates for hip and knee arthroplasty in patients participating in high-impact sports. Most of these studies report that participation in sporting activities following total joint arthroplasty refers to increased polyethylene wear and debris, which could eventually result in implant failure. With recent advances in implant technology and surgical technique, the survival rates for modern prosthetic designs and patients with these high demands are promising. Various studies assessing the association between clinical outcome and participation in tennis did not demonstrate a harmful effect on implant survival rates. Although the majority of these studies do not reflect a true representation of the average patient undergoing total joint arthroplasty, more surgeons are confronted with the patients' desire to continue with sports activity. To optimise results, patients who demand higher levels of activity must be carefully selected, and must have the motivation and drive to optimise their results. In general, all patients should be encouraged to remain physically active to improve general health, maintain good bone quality, and improve implant fixation. There is still a need for prospective, randomised controlled studies concerning high activity and its impact on total joint arthroplasty.

Arthroplasty, Replacement, Hip↗
PubMed2006

Displaced femoral neck fractures in the elderly: hemiarthroplasty versus total hip arthroplasty.

The incidence of femoral neck fracture among the elderly in the United States is expected to increase dramatically because of the anticipated explosion in the population aged 65 years and older, increased life expectancy, and the rising incidence of osteoporosis. The resulting public health implications may be significant, with annual hospital admissions resulting from hip fracture projected to increase to 700,000 by 2050, and with annual spending on hip fracture care expected to exceed 15 billion dollars within a few years. The decision to perform internal fixation, unipolar hemiarthroplasty, bipolar hemiarthroplasty, or THA must be based on patient mental status, living arrangement, level of independence and activity, and bone and joint quality.

Aged↗
PubMed2006

Hip resurfacing arthroplasty.

Hip resurfacing arthroplasty is a type of hip replacement that involves capping the femoral head and preserving bone of the proximal femur. Metal-on-metal surface replacements have been manufactured since the early 1990s. Recent studies indicate excellent clinical results with low failure rates at 1- to 5-year follow-up. Although these early results are encouraging, resurfacing devices must be used with caution because less is known about their long-term safety and efficacy. The best candidates for resurfacing are patients younger than age 60 years with good bone stock. The surgical approach is similar to that for standard total hip replacements, but with slightly more dissection because the femoral head must be preserved and displaced to visualize the acetabulum. To reduce complications, resurfacing arthroplasty should be performed by surgeons who have received training specifically in this technique.

Arthroplasty, Replacement, Hip↗
PubMed2006

Surgical treatment of osteonecrosis of the hip.

Various surgical procedures are used in patients with osteonecrosis of the hip. Patients with precollapse of the femoral head are generally treated with head-preserving procedures (core decompression, various bone grafting techniques, and osteotomies), whereas those with collapse of the femoral head and/or arthritis may require arthroplasty. The arthroplasty options available include limited femoral resurfacing arthroplasty, metal-on-metal resurfacing arthroplasty, or total hip replacement. The indications, techniques, and early outcomes of some of these procedures for treatment of osteonecrosis of the hip merit discussion.

Femur Head Necrosis↗
PubMed2006

Use of modular large femoral heads without liners in hip arthroplasty.

The use of large-diameter femoral heads in total hip arthroplasty appears to reduce the risk for dislocation, and potentially improve articular wear. Moreover, large-diameter total hip femoral heads have been determined to increase range of motion. The purpose of this study was to report our experiences with this new device. In our patient cohort, many patients have done extremely well in the short-term with this new device, and it seems these patients function better than those with a standard total hip arthroplasty. The patients who experience less pain are able to return to full activities postoperatively. The preliminary results of this study are encouraging, and large femoral head prosthesis appears to be a great choice for orthopaedic surgeons in primary total hip arthroplasty.

Adult↗