Relationship between bone ingrowth, mineral apposition rate, and osteoblast activity.

To better understand skeletal attachment of porous coated total hip and knee implants over time, this study investigated the dynamics of osteoblast populations at the interface of porous coated implants in a weight-bearing ovine model. The relationship between cancellous bone ingrowth, mineral apposition rate (MAR), and osteoblast activity indicators such as osteoblast area, relative osteoblast number, osteoid width, and osteoid area (O.Ar.) were investigated. The data demonstrated that the percent O.Ar. was a marginally significant predictor of bone ingrowth and MAR over time, suggesting that the amount of osteoid present influenced bone ingrowth and MAR in the porous coated implants. The data also demonstrated that all osteoblast activity indicators were significantly greater in the porous coated region compared to the host bone region, while controlling for in situ time (p < 0.05). This may have been due to the trauma of implantation or the influence of the implant load on the bone tissue promoting a regional acceleratory phenomenon. The localized response suggests that specific therapies may be developed to affect the physiology of osteoblasts at the interface of implants, which may allow for improve skeletal attachment of biomaterials and clinical outcomes of cementless joint replacements.

High tibial osteotomy with a calibrated osteotomy guide, rigid internal fixation, and early motion. Long-term follow-up.

BACKGROUND: We studied the results of sixty-four valgus-producing high tibial osteotomies performed with the use of a calibrated osteotomy cutting guide and rigid internal fixation, and followed by early motion, in fifty-six patients who had medial unicompartmental osteoarthritis and varus malalignment. Long-term studies have demonstrated that a high tibial osteotomy performed with staple fixation and followed by immobilization in a cast has an expected survival rate of approximately 85 percent at five years and 60 percent at ten years (in studies of ninety-five knees and 213 knees, respectively). To the best of our knowledge, there are no long-term reports on high tibial osteotomies performed with a calibrated osteotomy cutting guide and rigid internal fixation and followed by early motion. METHODS: The indications for high tibial osteotomy were medial unicompartmental osteoarthritis and varus malalignment. A lateral closing-wedge osteotomy was performed. The patients were reexamined to obtain a knee score, to make lateral radiographs of both knees, and to make a full-length anteroposterior radiograph (showing the entire lower extremity, including the hip and ankle) of the involved knee with the patient standing. RESULTS: Twenty-one knees were treated with a subsequent total knee arthroplasty at an average of sixty-five months after the high tibial osteotomy. The remaining forty-three knees had a good or excellent clinical result, with an average knee score of 94 points at an average of 8.5 years after the osteotomy. Survivorship analysis showed an expected rate of survival, with conversion to a total knee arthroplasty as the end point, of 85 percent at five years and 53 percent at ten years. No patient had patella baja postoperatively. There were six complications: four superficial wound infections, one superficial-vein thrombosis, and one delayed union (union occurred at five months). CONCLUSIONS: High tibial osteotomy has been criticized because of a high rate of complications, a loss of effectiveness with time, and the difficulty of conversion to a total knee arthroplasty secondary to patella baja. In our series, in which an osteotomy was performed with a calibrated osteotomy cutting guide and rigid internal fixation and was followed by early motion, the rate of complications was low and approximately two-thirds of the knees had a good or excellent clinical result at an average of 8.5 years. Conversion to a total knee arthroplasty was accomplished without difficulty in the patients who had this procedure. We highly recommend high tibial osteotomy with a calibrated osteotomy cutting guide, rigid internal fixation, and early motion for patients who wish to continue an active lifestyle.

Arthroscopic partial medial meniscectomy in the older patient.

We reviewed the cases of sixty-three patients who were more than forty years old when they underwent arthroscopic partial medial meniscectomy. Thirty-five patients returned for clinical evaluation and another eight were evaluated by questionnaire and telephone interview. Over the thirty-five-month follow-up period, progressive varus deformity and medial joint-space narrowing were not observed. Of the twenty-seven knees in Group I (non-degenerative tears) that underwent arthroscopic partial meniscectomy, satisfactory results were found in 96 per cent. Of the seventeen knees in Group II (degenerative tears) over-all satisfactory results were found in only 65 per cent. A history of pre-existing degenerative arthritis in patients with degenerative tears seemed to correlate with a less favorable outcome.

Osteotomy of the first cuneiform as treatment of residual adduction of the fore part of the foot in club foot.

An osteotomy of the first cuneiform was performed on eighteen feet in fourteen patients with residual deformity of congenital club foot. The average correction was 72 per cent for the adduction of the fore part of the foot and 47 per cent for the equinus deformity of the fore part of the foot.

Porous-coated metal-backed patellar components in total knee replacement. A postmortem retrieval analysis.

The use of porous-coated metal-backed patellar components to achieve consistent fixation by bone ingrowth and to provide relief of pain warrants serious scrutiny. We conducted a quantitative postmortem investigation of eleven consecutively retrieved components with use of high-resolution contact radiographs, electron microscopy, and histological analysis. The implants had been in situ for a mean (and standard deviation) of 45+/-36 months (range, one to eighty-four months). Analysis of the high-resolution contact radiographs revealed that a mean of 86+/-12 per cent (range, 61 to 100 per cent) of the porous coating was in contact with the host bone. Backscattered electron imaging showed that the mean volume fraction of bone ingrowth was 13+/-9 per cent (range, 0 to 30 per cent). No significant difference was detected, with the numbers available, between the volume fraction of the bone ingrowth measured in the porous coating and that of the host cancellous bone in the patellae.

Knee stability in orthotic knee braces.

The ability of six commercially available orthotic knee braces to stabilize ligamentous injuries of the knee was evaluated using fresh cadaver specimens. Anterior, valgus, and rotational forces were applied to the intact knee, after the anterior cruciate and medial collateral ligaments were cut, and after application of the knee braces. Bony displacement was measured using half pins and an external fixator applied to the tibia and femur. There was a significant difference in brace performance, most likely due to differences in brace design. Of the six braces tested, the 3D 3-Way Brace provided the greatest knee stability.

Compressive strength mapping of femoral head trabecular bone.

The purpose of this study was to develop a test protocol and complete a relative three-dimensional mapping of the local trabecular bone compressive strengths in healthy and osteoarthritic femoral heads. Five fresh frozen cadaveric femoral heads were compared to five fresh frozen osteoarthritic femoral heads obtained from patients undergoing total hip replacement. Each femoral head was coronally sectioned into eight 5 mm slices, which were compression-tested at 20 sites using a hydraulic testing machine. The results of the femoral head compressive strengths were normalized, mapped, and evaluated. The test protocol produced reproducible results and allowed the determination of diseased portions of osteoarthritic bone. The regions of high compressive strength were similar for normal and diseased bone and were located in the superior medial portions of the head. Ultimate stress was higher in diseased bone than in normal bone, while the yield point and stiffness of diseased bone was lower than for healthy bone.

Patellofemoral replacement: the third compartment.

Isolated patellofemoral arthritis is a common condition and there are varying opinions on the most effective treatments. Non-operative and operative treatments have failed to demonstrate effective long-term treatment for those in an advanced stage of the condition. Newer designs and increased technology in patellofemoral replacement (PFR) have produced more consistent outcomes. This has led to a renewed enthusiasm for this procedure. Newer PFR prostheses have addressed the patellar maltracking issues plaguing some of the older designs. Short-term results with contemporary prostheses and new technology are described here.

High tibial osteotomy. Use of an osteotomy jig, rigid fixation, and early motion versus conventional surgical technique and cast immobilization.

High tibial osteotomy (HTO) using conventional surgical technique and cast immobilization was compared to HTO using an osteotomy jig, rigid internal fixation, and early motion. Fifteen patients (19 knees) had conventional HTO. The mean preoperative femoral-tibial angle was 2.5 degrees of varus, and the mean postoperative angle was 6.5 degrees of valgus. Two knees were undercorrected and eight knees (42%) had associated complications. Twenty patients (21 knees) had HTO utilizing the new surgical technique and postoperative management. The mean preoperative femoral-tibial angle was 2.3 degrees varus, and the mean postoperative angle was 7.6 degrees valgus. One knee was undercorrected (less than 4 degrees valgus) and one knee (5%) had an intraoperative intraarticular fracture. High tibial osteotomy with an osteotomy jig to provide accurate correction, and rigid internal fixation to allow early motion, is an attractive alternative to conventional HTO.