Showing papers in "Clinical Orthopaedics and Related Research in 1999"

Autologous chondrocyte transplantation.

Abstract: The intrinsic capacity of cartilage to repair chondral injuries is poor. Different techniques to induce cartilage repair with the use of extrinsic chondrogeneic cell sources have been explored in experimental models. Cells can be harvested autologously or as allografts from a healthy part of the donor tissue, isolated, expanded in vitro, and finally implanted into the defect in high densities. Pure chondrocytes, epiphyseal or mature, allogeneic or autologous, and other types of mesenchymal cells have been used. The composition and structure of the extracellular cartilage matrix are maintained through a balance of anabolic and catabolic activities controlled by the unique chondrocytes. They keep the cartilage alive; they alone maintain it and regulate it. It therefore seems important to use true committed chondrocytes to repair a local cartilaginous defect. The rational basis for the use of committed autologous chondrocytes in combination with a covering periosteal membrane in the treatment of deep cartilage defects is presented.

Anterior femoroacetabular impingement after periacetabular osteotomy.

Abstract: As experience with the Bernese periacetabular osteotomy has grown, an unexpected observation in a group of patients has alerted the authors to the risk of a secondary impingement syndrome that may occur some time after the periacetabular osteotomy. This possibly may explain residual pain and limited range of motion in a larger group of patients. The impingement is produced by abutment of the femoral head or head to neck junction on the anterior rim of the properly aligned acetabulum. The symptoms are those of restricted flexion, and limited or absent internal rotation in flexion, with variable groin pain. Magnetic resonance imaging studies may reveal acetabular labral disease and adjacent cartilage damage associated with the impingement. Lack of anterior or anterolateral offset between the femoral neck and head results in neck to rim contact when the hip is flexed and/or internally rotated. Before the periacetabular osteotomy this is compensated by the lack of anterior acetabular coverage, but after proper correction the mismatch becomes apparent. The authors recently have devised a routine during the periacetabular osteotomy procedure whereby after the acetabular fragment is corrected into the desired position, the joint is opened, visually inspected, and palpated for impingement with the hip flexed and internally rotated. When necessary, a resection osteoplasty of the femoral neck to head junction is performed to improve the head and neck offset and reduce the anterior contact. This, in the short term, has provided satisfactory prevention of postoperative impingement.

Histologic analysis of tissue after failed cartilage repair procedures.

Abstract: This study evaluated the composition of reparative tissue retrieved during revision surgery from full thickness chondral defects in 18 patients in whom abrasion arthroplasty (n = 12), grafting of perichondrial flaps (n = 4), and periosteal patching augmented by autologous chondrocyte implantation in cell suspension (n = 6) failed to provide lasting relief of symptoms. The defects were graded by gross appearance, and all of the tissue filling the defect was retrieved. Histologic evaluation included histomorphometric analysis of the percentage of selected tissue types in cross sections. Immunohistochemistry was performed using antibodies to Types I, II, and X collagen. The histologic appearance of material retrieved after abrasion arthroplasty was that of fibrous, spongiform tissue comprising Type I collagen in 22% ± 9% (mean ± standard error of the mean) of the cross sectional area, and degenerating hyaline tissue (30% ± 10%) and fibrocartilage (28% ± 7%) with positive Type II collagen staining. Three of four specimens obtained after implantation of perichondrium failed as a result of bone formation that was found in 19% ± 6% of the cross sectional area, including areas staining positive for Type X collagen, as an indicator for hypertrophic chondrocytes. Revision after autologous chondrocyte implantation was associated with partial displacement of the periosteal graft from the defect site because of insufficient ongrowth or early suture failure. When the graft edge displaced, repair tissue was fibrous (55% ± 11%), whereas graft tissue attached to subchondral bone displayed hyaline tissue (to 6%) and fibrocartilage (to 12%) comprising Type II collagen at 3 months after surgery. Evaluation of retrieved repair tissue after selected cartilage repair procedures revealed distinctive histologic features reflecting the mechanisms of failure.

Survivorship of the high tibial valgus osteotomy : A 10- to 22-year followup study

Abstract: The results of 106 high tibial valgus osteotomies in 85 patients were evaluated after a minimum 10-year followup to determine survivorship, complications, and risk factors associated with failure. Using Kaplan-Meier survivorship analysis, 73% of patients at 5 years, 51% of patients at 10 years, 39% at 15 years, and 30% at 20 years after high tibial osteotomy had not required conversion of the high tibial osteotomy to a total knee arthroplasty. Univariate Cox regression analysis of risk factors showed that age older than 50 years, previous arthroscopic debridement, presence of a lateral tibial thrust, preoperative knee flexion less than 120°, insufficient valgus correction, and development of delayed union or nonunion were significantly associated with probability of early failure. Multivariate Cox regression analysis showed that a body mass index of less than 25 kg/m 2 , presence of a lateral tibial thrust, and development of delayed union or nonunion were significantly associated with probability of early failure. Using recursive partitioning analysis of risk factors with the Wilcoxon test, a subset of patients who were younger than 50 years of age and who had preoperative knee flexion greater than 120° had a probability of survival after high tibial osteotomy approaching 95% at 5 years, 80% at 10 years, and 60% at 15 years. These results suggest that survival of high tibial osteotomy can be improved through careful patient selection and surgical technique.

Bernese periacetabular osteotomy.

Abstract: Seventy-five symptomatic dysplastic hip joints (63 patients) were treated with the Bernese periacetabular osteotomy during a period of 44 months. The mean patients' age was 29 years (range, 13-56 years) and the female:male ratio was 3.4:1. Group III dysplasia according to Severin was seen in 50% and Group IV dysplasia was seen in 44% of the patients. Osteoarthritis was present in 58% of the patients. Followup was obtained at a mean of 11.3 years (range, 10-13.8 years) in 71 hip joints (95%). Radiographic measurements of the lateral center edge angle, anterior center edge angle, acetabular index, lateralization of the femoral head, and intactness of Shenton's line showed a high correction potential of this type of osteotomy. In 58 patients (82%) the hip joint was preserved at last followup with a good to excellent result in 73%. Unfavorable outcome was significantly associated with higher age of the patient, moderate to severe osteoarthritis at surgery, a labral lesion, less anterior coverage correction, and a suboptimal acetabular index. Major complications were encountered in the first 18 patients including an intraarticular cut in two, excessive lateralization in one, secondary loss of correction in two and femoral head subluxation in three patients.

Tissue engineering of bone. Cell based strategies.

Abstract: Skeletal tissue regeneration requires the interaction of three basic biologic elements: cells, growth and differentiation factors, and extracellular matrix scaffolds. Therapeutic approaches for tissue engineered repair of bone defects have attempted to mimic the natural process of bone repair by delivering a source of cells capable of differentiating into osteoblasts, inductive growth and differentiation factors, or bioresorbable scaffolding matrices to support cellular attachment, migration, and proliferation. Sophisticated designs even have tried to combine two or more of these elements. The development of cell based approaches has advanced dramatically in recent years as an understanding of musculoskeletal cell biology improves. Cell based approaches do not depend on the presence of local osteoprogenitors for the synthesis of new bone and, as a result, they particularly are attractive for patients who have a diminished pool of these progenitors, or in whom the host tissue bed has been compromised. This review highlights the development of cell based approaches for the tissue engineering of bone, and offers perspectives on the optimal elements for success. Although logistical and regulatory issues remain to be solved, cell based therapies for the repair of clinically significant bone defects rapidly are approaching clinical feasibility.

Effect of rotational alignment on patellar tracking in total knee arthroplasty.

Abstract: Forty-four consecutive patients (65 knees) who underwent identical condylar type total knee arthroplasty were evaluated retrospectively. In 22 of the patients (32 knees), the femoral component was set parallel to the posterior condylar axis (neutrally aligned group). In the remaining 22 patients (33 knees), it was set in an external rotation position of 3 degrees to 5 degrees relative to the axis (externally aligned group). Of the total knee arthroplasties in the neutrally aligned group, 34% required lateral release, compared with only 6% in the externally aligned group; patellar tracking in the externally aligned group was significantly better than that in the neutrally aligned group. Postoperative measurements performed using computed tomography scans showed that the mean angle between the prosthetic posterior condylar axis and the transepicondylar axis was 7.9 degrees in the neutrally aligned group and 3.2 degrees in the externally aligned group. The external rotation setting of the femoral component diminished the need for lateral retinacular release and may decrease the rate of patellofemoral complications that occur after total knee arthroplasty.

Minimum 10-year-results of extensively porous-coated stems in revision hip arthroplasty.

Abstract: Obtaining predictable, stable fixation of revision femoral implants is important for the long-term success of revision hip arthroplasty. The authors report on minimum 10 years clinical and radiographic followup of 170 patients with extensively coated cementless revision femoral components. With a range of followup of 10 to 16 years and a mean of 13.2 years, a survivorship of greater than 95% was reported. Clinically, the average Postel-D'Aubigne pain and walking score improved from a preoperative score of 5.4 points to 10.8 points postoperatively. Eighty-two percent of the hips had radiographic evidence of a bone-ingrown prosthesis and 13.9% had evidence of stable fibrous fixation. Four percent of stems were unstable as seen on radiographs. Six stems were revised to larger extensively coated stems and one stem is causing pain and is unstable but has yet to be revised. The overall mechanical failure rate was 4.1%. Stress shielding was greatest in patients with stems larger than 16.5 mm and in osteoporotic bone (Dorr Type C). Nine percent of patients had significant thigh pain including all of the patients with unstable stems. In the presence of bone loss in the proximal metaphyseal region of the femur, fixation of the femoral component is predictable when optimizing prosthetic-bone fit in the diaphyseal region of the femur using an extensively coated femoral component.

Bone repair techniques, bone graft, and bone graft substitutes.

Abstract: This paper reviews the techniques and materials (bone graft and bone graft substitutes) that currently are used to treat nonunions and bone defects. The techniques reviewed are intramedullary nailing, plating, distraction osteogenesis, and electric stimulation. Bone graft and bone graft substitutes reviewed are as follows: vascularized bone transfers; autogenous bone graft; autogenous bone marrow; dimineralized bone matrix; growth factors; calcium sulphate; calcium phosphates; and allograft. The goal of management of fractures, nonunions, and segmental bony defects, is the return of function as quickly and completely as possible. Techniques and management strategies constantly are evolving to accomplish this goal. This paper reviews the history, indications, and limitations of bone repair techniques, methods of bone grafting, and materials available as bone graft substitutes.

Wear and lubrication of metal-on-metal hip implants

Abstract: The implication of polyethylene wear particles as the dominant cause of periprosthetic osteolysis has created a resurgence of interest in metal-on-metal implants for total hip arthroplasty because of their potential for improved wear performance. Twenty-two cobalt chromium molybdenum metal-on-metal implants were custom-manufactured and tested in a hip simulator. Accelerated wear occurred within the first million cycles followed by a marked decrease in wear rate to low steady-state values. The volumetric wear at 3 million cycles was very small, ranging from 0.15 to 2.56 mm3 for all implants tested. Larger head-cup clearance and increased surface roughness were associated with increased wear. Independent effects on wear of material processing (wrought, cast) and carbon content were not identified. Implant wear decreased with increasing lambda ratio, a parameter used to relate lubricant film thickness to surface roughness, suggesting some degree of fluid film lubrication during testing. This study provided important insight into the design and engineering parameters that affect the wear behavior of metal-on-metal hip implants and indicated that high quality manufacturing can reproducibly lead to very low wear.

Unicompartmental knee arthroplasty. Clinical experience at 6- to 10-year followup.

Abstract: Sixty-two consecutive cemented modular unicompartmental knee arthroplasties in 51 patients were studied prospectively. At surgery, the other compartments had at most Grade 2 chondromalacia. The average age of the patients at arthroplasty was 68 years (range, 51-84 years). One patient was lost to followup and 10 died with less than 6 years followup. The average followup of the remaining 51 knees was 7.5 years (range, 6-10 years). The preoperative Hospital for Special Surgery knee score of 55 points (range, 30-79 points) improved to 92 points (range, 60-100 points) at followup; 78% (40 knees) had excellent and 20% (10 knees) had good results. The mean range of motion at followup was 120° with 26 knees (51%) having range of motion greater than 120°. One patient underwent revision surgery for retained cement, one patient underwent knee manipulation, and one patient underwent revision surgery at 7 years for opposite compartment degeneration and pain. Radiographically, 26 knees (51%) had at least one partial radiolucency. There were no complete femoral radiolucencies, but there were three complete tibial radiolucencies, all less than 2 mm. No component was loose as seen on radiographs. At final followup, five of the opposite compartments (10%) and three of the patellofemoral joints (6%) had some progressive radiographic joint space loss; this was less than a 25% loss in all but one knee component that was revised. At 6- to 10-years followup, cemented unicompartmental knee arthroplasty yielded excellent clinical and radiographic results. The 10-year survival using radiographic loosening or revision as the end point was 98%. Using stringent selection criteria, unicompartmental knee replacement can yield excellent results and represents a superb alternative to total knee replacement.

Articular cartilage transplantation. Clinical results in the knee.

Abstract: Between December 1983 and August 1991, 55 consecutive patients (55 knees) who underwent articular cartilage transplantation to their damaged knees were enrolled in the study. Average followup was 75 months (range, 11-147 months). Eight-two percent were younger than 45 years of age. Patients were evaluated through an 18-point scale, with 6 points each allocated to pain, range of motion, and function. An excellent knee was pain free, had full range of motion, and permitted unlimited activity. A good knee allowed full time employment and moderate activity. Eleven of 15 (73%) allografts transplanted 10 or more years ago were still good or excellent at the time of last followup. Overall, 42 of 55 (76%) knees that received the transplants were rated good or excellent. Specifically, 36 and 43 (84%) patients with unipolar transplants regained normal use of their resurfaced knee. The results after bipolar resurfacing were less encouraging, with only six of 12 (50%) knees rated good or excellent. The described technique of osteochondral shell allograft resurfacing of the knee capitalizes on the different healing potentials of bone and cartilage by transplanting the viable articular cartilage organ in its entirely along with just enough of the underlying bone to allow for graft incorporation through creeping substitution. The results support the use of fresh osteochondral shell allograft transplantation for the treatment of large, full thickness articular cartilage defects to the medial or lateral femoral condyles and to the patella.

Tissue engineering of ligament and tendon healing.

Abstract: Ligaments and tendons are bands of dense connective tissue that mediate normal joint movement and stability. Injury to these structures may result in significant joint dysfunction because they either heal by production of inferior matrix or do not heal at all. The process of ligament and tendon healing is complex and the roles of cellular and biochemical mediators continue to be elucidated. The expression of growth factors and growth factor receptors is modulated after injury, and cells from healing tissues are responsive to growth factors. Tissue engineering offers the potential to improve the quality of ligaments and tendons during the healing process. The concept is based on the manipulation of cellular and biochemical mediators to affect protein synthesis and improve tissue remodeling. Recently, novel techniques such as application of growth factors, gene transfer techniques, and cell therapy have shown promise and may become effective biologic therapies in the future. Many groups have been successful in introducing marker and therapeutic genes into ligaments and tendons. Cell therapy involves the introduction of mesenchymal progenitor cells as a pluripotent cell source into the healing environment. The combination of cell therapy with growth factor application via gene transfer offers new avenues to improve ligament and tendon healing.

Cryosurgery in the treatment of giant cell tumor. A long-term followup study.

Abstract: Between 1983 and 1993, 102 patients with giant cell tumor of bone were treated at three institutions. Sixteen patients (15.9%) presented with already having had local recurrence. All patients were treated with thorough curettage of the tumor, burr drilling of the tumor inner walls, and cryotherapy by direct pour technique using liquid nitrogen. The average followup was 6.5 years (range, 4-15 years). The rate of local recurrence in the 86 patients treated primarily with cryosurgery was 2.3% (two patients), and the overall recurrence rate was 7.9% (eight patients). Six of these patients were cured by cryosurgery and two underwent resection. Overall, 100 of 102 patients were cured with cryosurgery. Complications associated with cryosurgery included six (5.9%) pathologic fractures, three (2.9%) cases of partial skin necrosis, and two (1.9%) significant degenerative changes. Overall function was good to excellent in 94 patients (92.2%), moderate in seven patients (6.9%), and poor in one patient (0.9%). Cryosurgery has the advantages of joint preservation, excellent functional outcome, and low recurrence rate when compared with other joint preservation procedures. For these reasons, it is recommended as an adjuvant to curettage for most giant cell tumors of bone.

Relationship of acetabular wear to osteolysis and loosening in total hip arthroplasty

Abstract: Polyethylene wear and the subsequent development of periprosthetic osteolysis are the major factors limiting the longevity of total hip arthroplasties. A minority eventually loosen, but no clinically applicable system exists for accurate early prediction of failure. The relationship between acetabular wear and the development of loosening, osteolysis, and revision was investigated in 235 Charnley low friction arthroplasties. The average age of the patient at surgery was 31.7 years (range, 17-39 years), and the duration of followup averaged 234 months (19.5 years; range, 74-364 months). Total wear averaged 2.1 mm (range, 0-7.2 mm), and the average wear rate was 0.11 mm per year (range, 0-0.55 mm/year), with the wear rate of revised components being twice that of surviving ones (0.19 mm/year versus 0.09 mm/year). The prevalence of osteolysis (33 hips, 14%) and of acetabular and femoral component loosening and revision rose significantly with increasing wear. Osteolysis also was associated significantly with femoral component loosening and revision, but the presence of calcar changes was not (90 hips, 38%). Twenty-five year survivorship exceeded 90% for arthroplasties with a wear rate less than 0.1 mm per year, but 20-year survivorship of acetabular components with a rate greater than 0.2 mm per year was below 30%, and none survived 25 years. For every additional millimeter of wear, the risk of acetabular revision in any one year increased by 45% and for the femur increased by 32%.

Repair of full thickness rotator cuff tears. Gender, age, and other factors affecting outcome.

Abstract: Seventy-two full thickness rotator cuff tears (72 patients) were treated with an open rotator cuff repair between 1986 and 1993. The average postoperative followup was 54 months (range, 24-102 months; standard deviation, 22 months). Fifty-three (74%) patients had no pain, 16 (22%) patients had slight pain without restriction of activities, and three (4%) patients had moderate pain with activity compromise. Women with an associated biceps tendon rupture tended to have worse results. Women had a negative, statistically significant relationship between age and shoulder scoring scales, but age at the time of surgery was not related to any outcome variables for men. A rotator cuff tear greater than or equal to 5 cm2 as determined at the time of surgery was associated with a poorer outcome. The average University of California at Los Angeles score was 32 points (range, 7-35 points; standard deviation, 5 points). The average Constant-Murley score was 78 of 100 points (range, 12-95 points; standard deviation, 15 points). A yes response was given for an average of 10 of 12 questions on the Simple Shoulder Test (range, 0-12 questions; standard deviation, 3 questions). More than 4 years after open rotator cuff repair, patients had a 94% patient satisfaction rate with lasting relief of pain and improved function.

The Install Award. Survivorship of the high tibial valgus osteotomy. A 10- to -22-year followup study.

Abstract: The results of 106 high tibial valgus osteotomies in 85 patients were evaluated after a minimum 10-year followup to determine survivorship, complications, and risk factors associated with failure. Using Kaplan-Meier survivorship analysis, 73% of patients at 5 years, 51% of patients at 10 years, 39% at 15 years, and 30% at 20 years after high tibial osteotomy had not required conversion of the high tibial osteotomy to a total knee arthroplasty. Univariate Cox regression analysis of risk factors showed that age older than 50 years, previous arthroscopic debridement, presence of a lateral tibial thrust, preoperative knee flexion less than 120 degrees, insufficient valgus correction, and development of delayed union or nonunion were significantly associated with probability of early failure. Multivariate Cox regression analysis showed that a body mass index of less than 25 kg/m2, presence of a lateral tibial thrust, and development of delayed union or nonunion were significantly associated with probability of early failure. Using recursive partitioning analysis of risk factors with the Wilcoxon test, a subset of patients who were younger than 50 years of age and who had preoperative knee flexion greater than 120 degrees had a probability of survival after high tibial osteotomy approaching 95% at 5 years, 80% at 10 years, and 60% at 15 years. These results suggest that survival of high tibial osteotomy can be improved through careful patient selection and surgical technique.

Phantom limb, residual limb, and back pain after lower extremity amputations.

Abstract: This study describes the sensations and pain reported by persons with unilateral lower extremity amputations. Participants (n = 92) were recruited from two hospitals to complete the Prosthesis Evaluation Questionnaire which included questions about amputation related sensations and pain. Using a visual analog scale, participants reported the frequency, intensity, and bothersomeness of phantom limb, residual limb, and back pain and nonpainful phantom limb sensations. A survey of medication use for each category of sensations also was included. Statistical analyses revealed that nonpainful phantom limb sensations were common and more frequent than phantom limb pain. Residual limb pain and back pain were also common after amputation. Back pain surprisingly was rated as more bothersome than phantom limb pain or residual limb pain. Back pain was significantly more common in persons with above knee amputations. These results support the importance of looking at pain as a multidimensional rather than a unidimensional construct. They also suggest that back pain after lower extremity amputation may be an overlooked but very important pain problem warranting additional clinical attention and study.

Rotator cuff tears of the hip.

Abstract: Pain over the lateral aspect of the hip commonly is attributed to trochanteric bursitis. Typical findings include local tenderness and weakness of hip abduction. When conservative measures fail to relieve symptoms, surgical release of the iliotibial band over the greater trochanter has been recommended. In the management of seven such patients, an unusual finding was encountered: partial tear of the gluteus medius tendon at its attachment to the greater trochanter. Each patient presented with increasing hip pain of duration of months to years. There were no diagnostic findings on physical examination. Magnetic resonance imaging showed an abnormal signal within the tendon of gluteus medius and fluid within the trochanteric bursa. The disrupted tendons were reattached to bone with heavy nonabsorbable suture. At a median followup of 45 months (range, 21-60 months), all patients were free of pain.

Sudden Death During Primary Hip Arthroplasty

Abstract: The records of 23 patients who died intraoperatively during hip arthroplasty at the authors' institution were reviewed. Of the 38,488 hip arthroplasties in 29,431 patients performed between 1969 and 1997, there were 23 deaths during surgery. There were 15 women and eight men with a mean age of 80.9 years. Preoperative diagnoses were acute hip fracture (13 patients), pathologic fracture (four patients), femoral neck nonunion (one patient), osteoarthritis (four patients), and rheumatoid arthritis (one patient). Eleven patients undergoing cemented total hip arthroplasty died and 12 patients undergoing cemented hemiarthroplasty died. All deaths occurred because of irreversible cardiorespiratory disturbances that were initiated during cementing. There were no deaths among 12,551 patients receiving 15,411 uncemented hip arthroplasties during the 28-year period under review. Autopsy was performed in 13 patients. Bone marrow microemboli were seen in the lungs of 11 of 13 patients in whom an autopsy was performed and methylmethacrylate particles were seen in the lungs of three of 13 patients. These data suggest that elderly patients with preexisting cardiovascular conditions undergoing cemented arthroplasty, especially for fracture diagnosis, are at increased risk for intraoperative death compared with patients undergoing elective hip arthroplasty. In the latter years of the current study, modifications of the operative techniques designed to minimize intramedullary hypertension were associated with a reduction greater than three-fold in overall intraoperative mortality rate. These changes in surgical technique should be considered when cement fixation is used in patients thought to be at risk for having cardiopulmonary disturbances develop from venous embolization of marrow contents.

Long-term osteoarthritic changes in anterior cruciate ligament reconstructed knees.

Abstract: To consolidate the indications for anterior cruciate ligament reconstruction and clarify the long-term prognosis associated with current surgical and rehabilitation techniques, the incidence of osteoarthritis in arthroscopically anterior cruciate ligament reconstructed knees requires investigation. Seventy-two patients with anterior cruciate ligament ruptures who were active in sports requiring sidestepping and pivoting, or who had recurrent episodes of giving way, underwent arthroscopic bone-patellar tendon-bone anterior cruciate ligament reconstruction. These patients were evaluated for meniscal damage and osteoarthritic changes at the time of surgery and followed up for 7 years. Fifty-three patients underwent radiographic evaluation at 7 years, which included anteroposterior, lateral, skyline, and 30 degrees posteroanterior weightbearing views. Radiographic evaluation was performed by three independent surgeons and graded as per International Knee Documentation Committee criteria. Results revealed that knees with chronic anterior cruciate ligament deficiency, even those with intact menisci before reconstruction, suffered early osteoarthritic changes. More severe changes were seen with meniscectomy. Acute anterior cruciate ligament reconstruction with meniscal preservation was shown to have the lowest incidence of degenerative change. Controversy exists regarding the timing of anterior cruciate ligament reconstruction. This study supports early reconstruction of anterior cruciate ligament deficient knees before episodes of giving way occur in individuals intent on continuing activities that involve sidestepping and pivoting.

A clinical study of collagen meniscus implants to restore the injured meniscus

Abstract: The meniscus performs critical functions within the knee, and its loss frequently leads to osteoarthritis and irreversible joint damage. Because prosthetic replacement of the meniscus has proven ineffective, the authors used tissue engineering techniques to develop a resorbable collagen scaffold (collagen meniscus implant) that supports ingrowth of new tissue and eventual regeneration of the lost meniscus. Eight patients underwent arthroscopic placement the collagen meniscus implant to reconstruct and restore the irreparably damaged medial meniscus of one knee. Seven patients had one or more prior meniscectomies, and one patient had an acute meniscus injury. Patients were observed with frequent clinical, serologic, radiographic, and magnetic resonance imaging examinations for at least 24 months (range, 24-32 months). All patients underwent relook arthroscopy and biopsy of the implant regenerated tissue at either 6 or 12 months after implantation. All patients improved clinically from preoperatively to 1 and 2 years postoperatively based on pain, Lysholm scores, Tegner activity scale, and self assessment. Relook arthroscopy revealed tissue regeneration in all patients with apparent preservation of the joint surfaces based on visual observations. Histologic analysis confirmed new fibrocartilage matrix formation. Radiographs confirmed no progression of degenerative joint disease. The collagen meniscus implant is implantable, biocompatible, resorbable, and supports new tissue regeneration as it is resorbed. This tissue seems to function similar to meniscus tissue by protecting the chondral surfaces.

Cost effectiveness of anterior cruciate ligament reconstruction in young adults.

Abstract: The cost effectiveness of ligament reconstruction for acute anterior cruciate ligament tears in young adults was compared with the cost effectiveness of nonoperative management. A decision tree was constructed to predict the expected functional outcomes for operative and nonoperative treatment. Outcome probabilities were derived from the surgical and natural history literature. Cost data were based on averaged figures from the senior author's institution. Utility values were determined from a questionnaire administered to 285 local university students. Cost effectiveness was calculated in terms of dollars spent per additional quality adjusted life year provided by the surgical reconstruction for the initial 7 years after an injury. The operative strategy provided 5.10 quality adjusted life years versus 3.49 years for nonoperative treatment, yielding a marginal effectiveness of 1.61 quality adjusted life years. The estimated total costs of the operative and nonoperative strategies were $11,768 and $2333, respectively, for a marginal cost of $9435. The resulting marginal cost effectiveness ratio was $5857 per quality adjusted life year. These data suggest that, when based on functional outcomes, anterior cruciate ligament reconstruction is a cost effective method of treatment for acute tears in young adults. The cost effectiveness ratio predicted compares favorably with those of other health care interventions that aim to improve quality of life.

Aneurysmal bone cyst. A population based epidemiologic study and literature review.

Abstract: Aneurysmal bone cyst is a rare nonneoplastic expansile osteolytic bone lesion of unknown etiology. To the best of the authors' knowledge, no epidemiologic study concerning its incidence has been reported. The authors performed a retrospective, population based analysis of 94 patients with primary aneurysmal bone cyst and a literature review of 1002 patients regarding gender and age predilection. The annual incidence of primary aneurysmal bone cyst was 0.14 per 10(5) individuals. The male to female ratio was 1:1.04, and the median age was 13 years (range, 1-59 years). The results of this study and data compiled from the literature show that aneurysmal bone cysts occur significantly more often in female patients.

Effect of smoking on tibial shaft fracture healing

Abstract: Of 146 consecutive closed and Grade I open tibia shaft fractures treated with cast immobilization, external fixation, or intramedullary rod fixation during a 4-year period, 44 of 76 (58%) tibias of patients who smoked and 59 of 70 (84%) tibias of patients who did not smoke had followup to union or followup beyond 1 year. The demographics, fracture patterns, and treatments of the two groups were similar. Two of the 44 patients who smoked had nonunions at the 1-year followup, whereas none of the patients who did not smoke had nonunions. Of the 103 tibias with complete followup to union, the median time to clinical healing for patients who smoked (269 days) was significantly greater than that of patients who did not smoke (136 days). Likewise, there was a 69% delay in radiographic union in the group that smoked as interpreted by a radiologist blinded to the two groups. Statistical differences in clinical and radiographic healing rates between those who smoked and those who did not smoke were observed for patients receiving intramedullary fixation or external fixation. Statistical differences were not seen in the clinical and radiographic healing of tibias treated with cast immobilization, although tibias of patients who smoked took 62% longer to heal. The current data suggest that tibias of patients who smoke who require treatment with intramedullary nailing or external fixation require more time to heal than do those of patients who do not smoke.

Carrier Systems for Bone Morphogenetic Proteins

Abstract: Bone deficits can regenerate inherently, although when the amount of bone loss exceeds a critical limit, pseudarthrosis and fibrosis occur. Therapeutic intervention either with an autograft or allogeneic bank bone are traditional options to promote regeneration to overcome critical limits. However, liabilities with traditional treatments have inspired investigators to develop alternatives, such as combinations of biomimetic scaffolds and osteogenic regulatory molecules. The class of osteogenic regulatory molecules known as the bone morphogenetic proteins has several members that stimulate bone regeneration. Therapeutic applications of bone morphogenetic proteins require a well characterized carrier system to ensure safe and effective presentation at the implant site. Several carrier systems have been used to evaluate the sustained release and implant retention of recombinant human bone morphogenetic protein-2. The carrier systems used in this study include type I collagen, poly(D,L-lactide), and deorganified bovine bone. Pharmacokinetics of recombinant human bone morphogenetic protein-2 released from these systems were characterized in the rat ectopic assay. Pharmacokinetics were influenced by the implant carrier. For example, sustained release occurred with the collagen sponge. The recombinant human bone morphogenetic protein-2 from deorganified bovine bone resulted in a burst release at the first collection interval, but thereafter, appeared to bind irreversibly to the morphogen. The poly (D,L-lactide) systems showed a dose dependent sustained release pattern. These results indicate the physicochemical characteristics of a carrier system for recombinant human bone morphogenetic protein-2 impact the release kinetics and may have a profound influence on clinical outcome.

Biosynthetic bone grafting.

Abstract: The regeneration of bone remains an elusive yet important goal in the field of orthopaedic surgery. Despite its limitations, autogenous cancellous bone grafting continues to the most effective means by which bone healing is enhanced clinically. Biosynthetic bone grafts currently are being developed as an alternative to autogenous bone grafting. These grafts generally contain one or more of three critical components: (1) osteoprogenitor cells; (2) an osteoconductive matrix; and (3) osteoinductive growth factors. The importance of each of these components based on preclinical data supports their use in biosynthetic bone grafts. The use of growth factors such as bone morphogenetic proteins, transforming growth factor, platelet derived growth factor, and fibroblastic growth factor is reviewed in preclinical long bone defect and spinal fusion models. The use of bone marrow in preclinical and clinical settings is presented with specific emphasis given to the use of bone marrow as a source of osteoprogenitor cells and how the use of these cells can be enhanced with the use of bone morphogenetic protein-2. These data support the concept that although products that contain only one of the three key components of a bone graft may regenerate bone successfully, composites of the three key components will be more successful clinically.

Unicompartmental knee replacement. A minimum 15 year followup study.

Abstract: One hundred forty Marmor cemented unicompartmental knee replacements were inserted in 103 patients between 1975 and 1982. Fifty-two patients were women and 51 were men. One hundred twenty-five were medial compartment knee replacements and 15 were lateral knee replacements. At minimum 15 year followup 34 patients with 48 knee replacements were living; only four patients with four knee replacements were lost to followup. Average preoperative and final followup Hospital for Special Surgery knee scores were 57 and 82 points, respectively for the knees of living patients. Average preoperative and final followup Knee Society clinical and Knee Society functional scores were 31 and 42, and 85 and 71 points, respectively. For all knees, 10.2% (14 knees) were revised [4.4% (six knees) for tibial loosening, 5.1% (seven knees) for disease progression, and .7% (one knee) for pain]. For patients living 15 years, 12.5% (six knees) were revised [2.1% (one knee) for tibial loosening, and 10.4% (five knees) for disease progression]. Revision for failure of fixation of these unicompartmental replacements was comparable with that reported for fixed bearing total knee replacement. Disease progression (46%; 62 of 136 knees) and tibial subsidence with wear (10.4%; 15 of 136 knees, five of which required revision) were the major long term problems in this group of patients.

Metallic radial head arthroplasty improves valgus stability of the elbow.

Abstract: The stabilizing influence of radial head arthroplasty was studied in eight medial collateral ligament deficient anatomic specimen elbows. An elbow testing apparatus, which used computer controlled pneumatic actuators to apply tendon loading, was used to simulate active elbow flexion. The motion pathways of the elbow were measured using an electromagnetic tracking device, with the forearm in supination and pronation. As a measure of stability, the maximum varus to valgus laxity over the range of elbow flexion was determined from the difference between varus and valgus gravity loaded motion pathways. After transection of the medial collateral ligament, the radial head was excised and replaced with either a silicone or one of three metallic radial head prostheses. Medial collateral ligament transection caused a significant increase in the maximum varus to valgus laxity to 18.0 degrees +/- 3.2 degrees. After radial head excision, this laxity increased to 35.6 degrees +/- 10.3 degrees. The silicone implant conferred no increase in elbow stability, with a maximum varus to valgus laxity of 32.5 degrees +/- 15.5 degrees. All three metallic implants improved the valgus stability of the medial collateral ligament deficient elbow, providing stability similar to the intact radial head. The use of silicone arthroplasty to replace the radial head in the medial collateral ligament deficient elbow must be questioned. Metallic radial head arthroplasty provides improved valgus stability, approaching that of an intact radial head.

Early versus delayed surgery for acute cervical spinal cord injury.

Abstract: The optimal timing of surgical intervention in cervical spinal cord injuries has not been defined. The goals of the study were to investigate changes in neurologic status, length of hospitalization, and acute complications associated with surgery within 3 days of injury versus surgery more than 3 days after the injury. All patients undergoing surgical treatment for an acute cervical spinal injury with neurologic deficit at two institutions between March 1989 and May 1991 were reviewed retrospectively. Forty-three patients initially were evaluated. At one institution, patients with neurologic spinal injuries had surgical intervention within 72 hours of injury. At the other institution, patients underwent immediate closed reduction with subsequent observation of neurologic status for 10 to 14 days before undergoing surgical stabilization. This study indicates that patients who sustain acute traumatic injuries of the cervical spine with associated neurologic deficit may benefit from surgical decompression and stabilization within 72 hours of injury. Surgery within 72 hours of injury in patients sustaining acute cervical spinal injuries with neurologic involvement is not associated with a higher complication rate. Early surgery may improve neurologic recovery and decrease hospitalization time in patients with cervical spinal cord injuries.