Towards a standard in assessment of bone cutting for total knee replacement.

Arthroplasty outcome is influenced by the 'quality' of bone preparation for implant insertion. Surgeons face increasing choices of technique and instrumentation, yet clinical scoring methods assess the overall outcome and patient satisfaction but not the bone cuts directly. 'Quality management' of bone reshaping is needed to evaluate different bone cutting methods and computer assisted orthopaedic surgery (CAOS) systems. Analyses and experiments in this study were formulated for measurement and computation of four quantitative characteristics of bone preparation 'quality' and produced a highly condensed index for each. These represented (a) surface finish of cuts, (b) implant fit/looseness possible with the cut shape, (c) implant location/misalignment, and (d) accuracy of individual planar cuts. Assessment of synthetic bone cuts verified the robustness of the method for wide application in arthroplasty intraoperatively, in vitro and for comparing navigation systems.

Repair of segmental bone defects in the rat: an experimental model of human fracture healing.

Bone repair models in animals may be considered relevant to human fracture healing to the extent that the sequence of events in the repair process in the model reflect the human fracture healing sequence. In the present study, the relevance of a recently developed segmental defect model in rat fibula to human fracture healing was investigated by evaluating temporal progression of rigidity of the fibula, mineral content of the repair site, and histological changes. In this model, a surgically created 2-mm-long defect was grafted with a 5-mm-long tubular specimen of demineralized bone matrix (DBM) by inserting it over the cut ends of the fibula. The temporal increase in rigidity of the healing fibula demonstrated a pattern similar to biomechanical healing curves measured in human fracture healing. This pattern was characterized by a short phase of rapidly rising rigidity during weeks 4-7 after surgery, associated with a sharp increase in the mineral content of the repair tissue. This was preceded by a phase of nearly zero rigidity and followed by a phase of slow rate of increase approaching a plateau. Histologically, chondroblastic and osteoblastic blastema originating from extraskeletal and subperiosteal (near fibula-graft junction) regions, infiltrated the DBM graft during the first 2 weeks. The DBM graft assumed the role of a "bridging callus." By weeks 6-8, most of the DBM was converted to new woven and trabecular bone with maximal osteoblastic activity and minimal endochondral ossification. Medullary callus formation started with direct new bone formation adjacent to the cortical and endosteal surfaces in the defect and undifferentiated cells in the center of the defect at 3 weeks. The usual bone repair process in rodents was altered by the presence of the DBM graft to recapitulate the sequential stages of human fracture healing, including the formation of a medullary callus, union with woven and lamellar bone, and recreation of the medullary canal.

Demineralized bone matrix as a biological scaffold for bone repair.

Experimental models were created in rat fibula to represent impaired bone healing so that biological deficiencies that cause bone repair to fail or to be delayed may be investigated. These models consist of a 4-mm-long segmental defect, created in rat fibula by osteotomy, and fitted with a 7-mm-long tubular specimen of demineralized bone matrix (DBM) over the cut ends of the fibula. The experiments in this study involved various modifications of the DBM scaffold designed to reduce its osteoinductive activity: steam sterilization (sDBM), ethylene oxide sterilization (eoDBM), trypsin digestion (tDBM), and guanidine hydrochloride extraction (gDBM). Bone healing was evaluated by bending rigidity of the fibula and mineral content of the repair site at 7 weeks post-surgery. The sDBM scaffolds resorbed completely by 7 weeks and hence this model was a nonhealing negative control. Rigidities in the unmodified DBM and tDBM groups were comparable, whereas in the gDBM and eoDBM groups it was significantly reduced. Histologically, in the 4-mm defects repaired with unmodified DBM, direct and endochondral bone formation in the scaffold and the defect resulted in a neocortex consisting of woven and lamellar bone uniting the broken bone by 7 weeks post-surgery. We conclude that the eoDBM and gDBM groups represent failure or delay of the bone repair process when compared with the unmodified DBM group in which the process is analogous to normal bone healing.

The use of the vastus lateralis flap in patients with intractable infection after resection arthroplasty following the use of a hip implant.

Recurrent sepsis and breakdown of the tissues in the operative wound after resection arthroplasty is performed for a hip with an infection at the site of an implant present a formidable challenge. A review of the literature indicates that more than 25 per cent of patients had delayed healing, additional surgery, or persistent drainage after resection arthroplasty. Under these circumstances, muscle flaps may help provide definitive closure, cessation of drainage, and functional recovery of the extremity as well as a reduction in the length and cost of hospitalization. The successful use of a vastus lateralis flap in seven patients is described. The specific advantages are: the flap has a consistent reliably identified vascular pedicle which permits a wide arc of rotation; sufficient muscle volume enables large open wounds to be filled; the structural integrity of the muscle is not violated by previous operations; and no important functional deficit is attributable to the procedure.

Arthrodesis of the knee with a modular titanium intramedullary nail.

We retrospectively studied the results of arthrodesis of the knee with a modular titanium intramedullary nail that couples at the knee. The study group consisted of thirteen patients who had a malignant tumor around the knee, five who had failure of a total knee arthroplasty, and three who had a locally destructive benign tumor about the knee. All of the patients were followed for a minimum of two years. Through a single incision at the knee, one nail was inserted retrograde into the femur and the other, antegrade into the tibia; the two nails were joined at the level of the knee by a conical couple and were secured with locking screws. The diameters of the nails were different, to accommodate the dissimilar sizes of the tibial and femoral intramedullary canals. A solid osseous fusion was achieved in nineteen (90 per cent) of the twenty-one patients (sixteen who had had resection of a tumor and three who had had a failed arthroplasty), at an average of 8.4 months (range, three to nineteen months) after the operation. One patient had a delayed union, but fusion was achieved after additional bone-grafting. Of the sixteen patients who were available for clinical and radiographic evaluation at the time of the study, fifteen were satisfied with the over-all outcome and thirteen had either less pain or the same amount of pain as they had had preoperatively. There were no mechanical failures of the implant and no recurrences of tumor. Complications occurred in eight (38 per cent) of the twenty-one patients: three patients had a stress fracture, three had a peroneal nerve palsy (one of which was transient), one had a superficial wound infection, and one had reflex sympathetic dystrophy.

Long-term results of total hip arthroplasty in congenital dislocation and dysplasia of the hip. A follow-up note.

Twenty-three of twenty-nine hips that were previously reported on were studied at an average of fourteen years (range, eight to 16.5 years) after total hip arthroplasty with cement. The original arthroplasties had been performed between November 1971 and January 1976. In all hips, there was dislocation or severe dysplasia. In six hips, superolateral bone grafts were used to increase acetabular coverage. At the latest follow-up examination, seven hips were rated excellent; nine, good; and one, fair. There were six failures (26 per cent) that were revised: four hips (17 per cent) had a fractured Trapezoidal-28 stem, one had loose femoral and acetabular components, and one had loosening of only the acetabular component. Radiographic analysis of the remaining hips revealed that one had progressive acetabular radiolucencies. This patient had an excellent clinical result. Two-thirds of the failures were due to a fractured stem.

Polylactide/polyglycolide antibiotic implants in the treatment of osteomyelitis. A canine model.

Osteomyelitis with Staphylococcus aureus was established in the tibiae of twenty-six adult mongrel dogs. After confirmation of infection at four weeks, all animals had operative débridement and were then divided into three treatment groups. Group 1 (eight animals [sixteen tibiae]) was treated with parenteral administration of gentamicin (three milligrams per kilogram of body weight per day) every eight hours for four weeks. Group 2 (nine animals [nine tibiae]) was treated with a polymethylmethacrylate implant containing 100 milligrams of gentamicin that was placed in the tibia for six weeks. Group 3 (nine animals [nine tibiae]) was treated with a polylactide/polyglycolide implant containing 100 milligrams of gentamicin that was placed in the tibia for six weeks. All animals were killed at the end of treatment. At that time, specimens of tissue were obtained for quantitative culture as well as for antibiotic immunoassay. In the groups that had been treated with an implant, serum was obtained for the measurement of serum drug levels after débridement; after the implantation; four, seven, and twenty-one days postoperatively; and immediately before the animals were killed. The infection was eradicated in ten of the sixteen tibiae in Group 1, in eight of the nine tibiae in Group 2, and in all nine tibiae in Group 3.(ABSTRACT TRUNCATED AT 250 WORDS)

A femoral component inserted without cement in total hip arthroplasty. A study of the Tri-Lock component with an average ten-year duration of follow-up.

Seventy-four total hip arthroplasties in sixty-six patients were performed, between 1983 and 1986, with use of a Tri-Lock femoral component inserted without cement. This tapered cobalt-chromium component has a fixed head and a circumferential proximal porous coating. Follow-up was conducted with use of a questionnaire, physical examination, and radiographic analysis. At the time of the latest follow-up, fifteen patients (eighteen hips) had died, three patients (four hips) had been lost to follow-up, and one patient (one hip) had refused to participate in the follow-up study; however, the status of fifteen hips at the time of death could be verified. Thus, clinical follow-up data were available for sixty-six of the original seventy-four hips. The average age at the time of the operation was sixty-two years (range, seventeen to eighty-four years), and the average interval between the operation and the latest follow-up evaluation was 10.0 years (range, 8.3 to 11.6 years). The Harris hip score was determined for forty-three hips (forty-one patients) in which the prosthesis was in situ at the time of the latest follow-up. The score was good for thirteen hips and excellent for twenty-eight, so the rate of clinical success was 95 per cent. Two patients had a fair result. One of them had persistent pain and the other had limited motion, but neither had radiographic evidence of loosening of the femoral or acetabular component. All forty-one patients were satisfied with the result. The probability (with standard error) of survival of the femoral component at ten years, with revision as the end point, was 0.95 +/- 0.03. The rate of revision of the femoral component because of aseptic loosening was one (2 per cent) of sixty-six. The overall rate of aseptic loosening of the femoral component in the hips that were followed radiographically was two (4 per cent) of forty-seven. Only one (2 per cent) of the forty-seven acetabular cups had evidence of aseptic loosening. There was no radiographic evidence of distal osteolysis around the prostheses that were well fixed. Proximal osteolysis was present in five (11 per cent) of forty-seven hips, but none of the lesions compromised the stability of the prosthesis or the bone and there were no associated fractures. At an average of ten years postoperatively, the Tri-Lock femoral component functioned well overall and patient satisfaction was high.

Preoperative autologous donation for total joint arthroplasty. An analysis of risk factors for allogenic transfusion.

BACKGROUND: While autologous blood is commonly predonated to provide replacement of blood lost in orthopaedic procedures, few studies of patients managed with total joint replacement have addressed the problem of which patients are likely to benefit from an autologous blood-donation program. METHODS: A retrospective analysis of 489 consecutive patients who had had a total joint arthroplasty was performed to identify the risk factors for allogenic transfusion and to further define the indications for preoperative autologous blood donation. The operations included 247 total knee replacements (157 unilateral primary, thirty-two revision, and twenty-nine one-stage bilateral primary procedures) and 271 total hip replacements (163 primary and 108 revision procedures). Fifty-four percent (264) of the 489 patients donated a total of 527 units of blood (average, 2.0 units per patient) preoperatively. RESULTS: One hundred and ninety-one patients (39 percent) required a transfusion of autologous blood or allogenic blood, or both. One hundred and thirty-one patients (27 percent) received autologous blood, and eighty-two patients (17 percent) received a transfusion of allogenic blood; twenty-two patients (4 percent) received both autologous and allogenic blood. Neither form of transfusion caused serious complications. Fifty-six percent (295) of the 527 units of autologous blood were discarded. Autologous donation significantly decreased the requirements for allogenic transfusion (relative risk, 0.1; p<0.0001). It also caused the level of hemoglobin to decrease an average of 12.2 grams per liter from the time before donation to the time before the operation (p<0.0001). Factors that increased the risk for allogenic transfusion were a revision knee or hip procedure or a one-stage bilateral primary knee replacement (relative risk, 5.7; p<0.0001), an initial hemoglobin level of less than 130 grams per liter (relative risk, 5.6; p<0.0001), and an age of sixty-five years or older (relative risk, 2.8; p = 0.02). None of the sixty-seven patients who had a primary knee or hip arthroplasty and an initial hemoglobin level of 150 grams per liter or more required an allogenic transfusion. In addition, none of the sixty-three patients who had a primary arthroplasty, an initial hemoglobin level of between 130 and less than 150 grams per liter, and an age of less than sixty-five years required an allogenic transfusion. Eighty-three percent (115) of the 138 autologous units donated by the seventy patients in these two groups were discarded. These wasted units accounted for 39 percent of the 295 discarded units for the entire study sample. CONCLUSIONS: The efficiency of collection of autologous blood can be improved by identifying patients who have a very low risk of transfusion according to the type of arthroplasty, the initial level of hemoglobin, and age. Patients who have an initial hemoglobin level of at least 150 grams per liter or an initial hemoglobin level of between 130 and 150 grams per liter and an age of less than sixty-five years have a minimal risk of needing a transfusion during or after a primary total joint replacement. These patients should be apprised of their low risk so that they can make an informed decision regarding preoperative autologous donation.

Ceramic-on-polyethylene bearing surfaces in total hip arthroplasty. Seventeen to twenty-one-year results.

BACKGROUND: Polyethylene wear debris, and the resulting inflammatory response leading to osteolysis and loosening, is the primary mode of failure limiting the longevity of total hip replacements. Alternative bearing surfaces, including ceramic-on-polyethylene, have been investigated in an effort to decrease the amount of polyethylene wear debris. The purpose of this study was to evaluate the seventeen to twenty-one-year results of the use of ceramic-on-polyethylene total hip prostheses. METHODS: Sixty-four total hip prostheses were implanted with cement, by one surgeon, in fifty-six patients from 1978 to 1981. The average age at the index arthroplasty was sixty-nine years (range, fifty-one to eighty-four years). The components consisted of a cemented Charnley-Müller stem with a 32-mm modular alumina femoral head and a cemented all-polyethylene acetabular component. All patients who retained the index prosthesis were assessed clinically with use of Harris hip scores and were evaluated radiographically at the time of the latest follow-up. RESULTS: At the time of this latest follow-up, of the original sixty-four implants, eighteen (28%) were still in place and five (8%) had been revised. The remaining forty-one implants were in patients who had died and were functioning well until the patient's death. No patient was lost to follow-up. Of the eighteen hips with an intact prosthesis in the surviving patients, seven had an excellent clinical result; nine, a good result; and two, a fair result. One asymptomatic hip had definite radiographic evidence of femoral loosening. No hip had definite signs of acetabular loosening or evidence of osteolysis. Survivorship analysis revealed that the probability of survival of the prostheses without revision was 95% at five years, 95% at ten years, 89% at fifteen years, and 79% at twenty years. The mean linear and volumetric polyethylene wear rates were 0.034 mm/yr and 28 mm(3)/yr, respectively. There were no fractures of the ceramic heads. CONCLUSIONS: Outstanding long-term clinical and radiographic results were attained despite the use of what are now considered substandard techniques (an inferior stem design, a 32-mm head, and first-generation cementing techniques). The wear rates in this study are lower than previously reported metal-on-polyethylene wear rates and are consistent with the lowest reported in vivo ceramic-on-polyethylene wear rates. These findings support the consideration of ceramic-on-polyethylene bearing surfaces in total hip arthroplasty.

Contralateral total hip arthroplasty or ipsilateral total knee arthroplasty in patients who have a long-standing fusion of the hip.

We studied the cases of twenty patients who had had an ipsilateral total knee arthroplasty or a contralateral total hip arthroplasty, or both, long after one hip had been fused in an acceptable position. Between 1972 and 1986, we performed twenty-one total joint arthroplasties (on thirteen hips and eight knees) and followed two additional patients (one hip and one knee) in whom the operation had been performed elsewhere. The average age of the patients at the time of arthroplasty was fifty-seven years (range, thirty-one to eighty-one years), and the average time from arthrodesis to arthroplasty was thirty-two years (range, eleven to fifty-four years). The results of eighteen of the twenty-three arthroplasties were evaluated at an average of seven years and nine months postoperatively. Four of the remaining five patients, who were followed for an average of eight years, died of a cause that was unrelated to the arthroplasty. After the hip arthroplasty, five hips were rated excellent; five, good; one, fair; and three, poor. Each hip that had a poor result was revised twice for mechanical loosening. Three hips for which the result was not considered poor had progressive radiolucency. After the knee arthroplasty, three knees were rated excellent; four, good; one, fair; and one, poor (because of infection). Seven knees were manipulated a total of fifteen times. Only one patient had progressive symptomatic radiolucency, nine years after the insertion of a posterior stabilized prosthesis. Clinically important ligamentous instability was not encountered.(ABSTRACT TRUNCATED AT 250 WORDS)

Femoral preparation in cemented total hip arthroplasty: reaming or broaching?

Surgical techniques continue to be refined to improve the results of primary cemented total hip arthroplasty. Although there has been much research in the areas of cementation and implant design, little work has specifically addressed how bone preparation can be optimized on the femoral side. On the basis of available scientific data, it appears that the broach-only system has several potential advantages over the traditional ream-and-broach technique. Broaching is usually faster, leaves behind more bone stock, and may improve both microinterlock and macrointerlock. Additionally, the excess bone resulting from broaching without reaming does not seem to compromise fixation at the bone-cement interface. Such differences may become even more important as the indications for cemented hip arthroplasty broaden to include increasingly younger and more active patients, because revision in these individuals is likely. In most cases, reaming is probably counterproductive, although it may be advantageous when used to open the femoral canal, to prevent varus stem orientation, and to manage sclerosis or deformity of bone due to a preexisting hip disorder or the presence of internal fixation devices. Regardless of which method is chosen, good bone surface cleansing and cement penetration remain paramount. More studies comparing reamed and nonreamed preparation are necessary to resolve this controversial issue definitively.

Role of gentamicin-impregnated cement in total joint arthroplasty.

Palacos-Gentamicin (PG) was used in 130 joint arthroplasties at The Hospital for Special Surgery. At an average follow-up of 2.5 years (range, 2 to 5), the overall recurrence rate of infection was 3.8 per cent. Only one (2.0 per cent) infection occurred where the bacteria were sensitive to PG and there were no infections in the two-stage reimplantation group. There have been no adverse effects from the gentamicin and the inferior intrusion properties of the PG have not been reflected in the clinical or radiographic results.

Fracture of the femoral component. Analysis of failure and long-term follow-up of revision.

Although fracture of the femoral component is an uncommon mode of mechanical failure, when it does occur, symptoms may be dramatic. In addition, it presents the surgeon with one of the more challenging problems in revision total hip arthroplasty surgery. This study reviews the problem of femoral stem fracture and evaluates the stem failures and long-term follow-up of the revision for femoral component fractures performed at The Hospital for Special Surgery.

Emerging multiresistant strains: recommended precautions in the emergency room and surgical setting.

The current success in treatment of surgical site infections may be jeopardized by the continued emergence of antibiotic resistance in bacteria common to these infections. The effectiveness of vancomycin against methicillin-resistant staphylococci may decrease as more cases of VISA emerge. No currently available antimicrobial is consistently effective against certain strains of VRE and the potential emergence of VRSA. Orthopaedic surgeons soon may be in the undesirable position of having to eradicate organisms resistant to all available antibiotics. Several new antibiotics show promising activity and may be useful against these multidrug-resistant bacteria. However, as the history of bacterial resistance has taught us, it likely only will be a matter of time until these organisms adapt mechanisms of resistance to these new drugs. The key then lies, as it always has, in preventive measures. Surgeons, and all physicians, must adhere to the precautionary guidelines recently set forth by the CDC and HICPAC. Chief among these guidelines is the elimination of inappropriate antibiotic usage, especially inappropriate vancomycin use.

Technical considerations in difficult primary total hip arthroplasty.

Total joint replacement has become one of the more common orthopaedic operations, with approximately 240,000 major joint arthroplasties performed annually in the United States, a large percentage of these being of the hip. The vast majority of hip replacements are for the diagnosis of degenerative arthritis and are performed in patients greater than 60 years of age. Less commonly the procedure is performed for other diagnoses (eg, developmental disorders of the hip, inflammatory arthritis, and post-traumatic arthritis) and in younger patients. Each of these diagnoses are associated with unique characteristics posing an array of technical challenges for the surgeon. The purpose of this manuscript is to highlight the more common of these processes with emphasis on the technical difficulties encountered when reconstructing these hips.

The role of a composite, demineralized bone matrix and bone marrow in the treatment of osseous defects.

The efficacy of demineralized bone matrix (DBM) used alone and with bone marrow as a graft material in the treatment of osseous defects was evaluated in 48 patients. Of these 48 patients, 39 were available to follow up and review. Follow up averaged 19 months for all patients. In the entire series, 30 of 39 patients demonstrated osseous union for a 77% success rate. Patients with fracture nonunion represented the most recalcitrant group clinically, with union achieved in only 61% of these cases. Overall, the 39 patients grafted with DBM demonstrated healing that was comparable to results achieved with standard iliac crest bone graft. The results indicate the DBM and marrow composite grafting is a suitable alternative to autologous iliac crest bone graft for use in certain clinical situations, such as bone defects in children, comminuted fractures with associated bone loss, nonunited fractures, or to augment an intended arthrodesis site.

Two-stage reimplantation of the infected hip.

To determine the diagnosis of patients with infection after total hip replacement may be very difficult, and successful reimplantation is even more challenging. Surgical debridement, removal of all foreign material, and the prosthesis followed by antibiotic therapy are essential for successful eradication of the infection. Reimplantation of the hip allows for functional recovery of the patient. The optimal time for reimplantation of the prosthesis and the role of antibiotic impregnated cement is less clear. A review of the literature strongly favors a two-stage reimplantation with local antibiotic delivery with successful results of approximately 93%.

Human blood and marrow side population stem cell and Stro-1 positive bone marrow stromal cell numbers decline with age, with an increase in quality of surviving stem cells: correlation with cytokines.

Hematological deficiencies increase with aging leading to anemias, reduced hematopoietic stress responses and myelodysplasias. This study tested the hypothesis that side population hematopoietic stem cells (SP-HSC) would decrease with aging, correlating with IGF-1 and IL-6 levels and increases in bone marrow fat. Marrow was obtained from the femoral head and trochanteric region of the femur at surgery for total hip replacement (N=100). Whole trabecular marrow samples were ground in a sterile mortar and pestle and cellularity and fat content determined. Marrow and blood mononuclear cells were stained with Hoechst dye and the SP-HSC profiles acquired. Marrow stromal cells (MSC) were enumerated flow cytometrically employing the Stro-1 antibody, and clonally in the colony forming unit fibroblast (CFU-F) assay. Plasma levels of IGF-1 (ng/ml) and IL-6 (pg/ml) were measured by ELISA. SP-HSC in blood and bone marrow decreased with age but the quality of the surviving stem cells increased. MSC decreased non-significantly. IGF-1 levels (mean=30.7, SEM=2) decreased and IL-6 levels (mean=4.4, SEM=1) increased with age as did marrow fat (mean=1.2mmfat/g, SEM=0.04). There were no significant correlations between cytokine levels or fat and SP-HSC numbers. Stem cells appear to be progressively lost with aging and only the highest quality stem cells survive.