The neuromuscularly challenged patient

Degenerative problems of the hip in patients with childhood and adult onset neuromuscular disorders can be challenging to treat. Many orthopaedic surgeons are reluctant to recommend total hip replacement (THR) for patients with underlying neuromuscular disorders due to the perceived increased risks of dislocation, implant loosening, and lack of information about the functional outcomes and potential benefits of these procedures in these patients. Modular femoral components and alternative bearings which facilitate the use of large femoral heads, constrained acetabular components and perhaps more importantly, a better understanding about the complications and outcomes of THR in the patient with neuromuscular disorders, make this option viable. This paper will review the current literature and our experience with THR in the more frequently encountered neuromuscular disorders.

Cite this article: Bone Joint J 2014;96-B(11 Suppl A):27–31.

Hip joint replacement surgery for idiopathic osteoarthritis aggregates in families

In order to determine whether there is a genetic component to hip or knee joint failure due to idiopathic osteoarthritis (OA), we invited patients (probands) undergoing hip or knee arthroplasty for management of idiopathic OA to provide detailed family histories regarding the prevalence of idiopathic OA requiring joint replacement in their siblings. We also invited their spouses to provide detailed family histories about their siblings to serve as a control group. In the probands, we confirmed the diagnosis of idiopathic OA using American College of Rheumatology criteria. The cohorts included the siblings of 635 probands undergoing total hip replacement, the siblings of 486 probands undergoing total knee replacement, and the siblings of 787 spouses. We compared the prevalence of arthroplasty for idiopathic OA among the siblings of the probands with that among the siblings of the spouses, and we used logistic regression to identify independent risk factors for hip and knee arthroplasty in the siblings. Familial aggregation for hip arthroplasty, but not for knee arthroplasty, was observed after controlling for age and sex, suggesting a genetic contribution to end-stage hip OA but not to end-stage knee OA. We conclude that attempts to identify genes that predispose to idiopathic OA resulting in joint failure are more likely to be successful in patients with hip OA than in those with knee OA.

Outcome of metal-backed cementless patellar components: the effect of implant design

Failure of metal-backed cementless patellar components frequently has been observed clinically. To determine the effect of component design on clinical outcome, the authors reviewed the results of total knee arthroplasty with metal-backed patellar components of two different designs. The results of 168 total knee arthroplasties (Miller-Galante) with dome-shaped metal-backed patellar components and 93 total knee arthroplasties Miller-Galante II with modified dome-shaped metal-backed patellar components were reviewed. Kaplan-Meier survivorship was determined for both groups. Revision for patellar wear or failure was done or recommended in 36 Miller-Galante total knee arthroplasties. The cumulative survival rates at 3, 5, 7, and 9 years postoperatively were 99%, 92%, 81%, and 73%, respectively for this group. In contrast, only three of 93 Miller-Galante II patellar components required revision. Catastrophic patellar component failure, typically seen with the Miller-Galante metal-backed patellar components, was not observed with the Miller-Galante II components. Cumulative survival of the Miller-Galante II patella at 3, 5, 7, and 9 years postoperatively was 100%, 100%, 98.7%, and 93.2% respectively. The results of the current study show a dramatic reduction in metal-backed component failure by design changes incorporated into the modified dome-shaped Miller-Galante II patellar component and highlights the importance of design on the survival of cementless metal-backed patellar components.

Effect of resin type and manufacturing method on wear of polyethylene tibial components

The purpose of this study was to examine the effect of ultrahigh molecular weight polyethylene resin type and manufacturing method on wear of Miller-Galante I and II tibial knee components. Thirteen Miller-Galante I and 10 Miller-Galante II components were retrieved at revision surgery. The Miller-Galante I tibial components were made by direct compression molding of Hi-fax 1900 resin and the Miller-Galante II tibial components were made by machining from ram extruded rod of GUR 415 resin. Both generations were gamma radiation sterilized in air. The Miller-Galante I retrievals had significantly more wear damage in the form of scratching and embedded metallic debris, whereas the Miller-Galante II retrievals had significantly more wear damage in the form of delamination. For the implants with an implantation time of 5 years or more, the Miller-Galante II polyethylene had a significantly greater maximum density value than did the Miller-Galante I polyethylene. Examination of thin sections of the Miller-Galante II components revealed that delamination occurred through a subsurface region of severely oxidatively degraded polyethylene; no such subsurface degraded region was observed for the Miller-Galante I components. The results of this study suggest that delamination of polyethylene tibial components that have been gamma radiation sterilized (in air) is influenced by resin type or manufacturing method or both.

Clinical and radiographic outcomes of total hip arthroplasty with insertion of an anatomically designed femoral component without cement for the treatment of primary osteoarthritis. A study with a minimum of six years of follow-up

We evaluated the clinical and radiographic outcomes of 100 consecutive primary total hip arthroplasties in which a proximally coated anatomically designed femoral component was fixed without cement for the treatment of primary osteoarthritis. The minimum duration of follow-up was six years (average, 7.1 years). The eighty-eight patients who had the arthroplasties were followed prospectively with a standard clinical evaluation that involved use of the Harris hip score and a radiographic evaluation based on the criteria of the Hip Society. Bone ingrowth was evaluated with the method of Engh et al. The average age of the patients at the time of the operation was 62.6 years (range, thirty-nine to eighty-four years). Fifty-one patients were men and thirty-seven were women. The average preoperative Harris hip score was 48 points, with an average pain score of 15 points and an average function score of 26 points. Nonmechanical complications that necessitated a revision operation included one deep hematogenous infection, one late periprosthetic fracture, and a 0.5-inch (1.27-centimeter) limb-length discrepancy. At the time of the most recent follow-up, the average Harris hip score was 96 points, with an average pain score of 42 points and an average function score of 45 points. The prevalence of pain in the anterior part of the thigh was 5 percent (five hips). One patient had a revision of the femoral component because of aseptic loosening, and one had a revision of the acetabular component because of recurrent dislocations. Radiographic assessment revealed consistent evidence of proximal bone ingrowth. No complete radiolucent line was identified, except around the stem that had loosened. Twenty-seven femoral components were associated with slight pedestal formation. No osteolytic lesion of the femur was identified. Nonprogressive pelvic osteolysis was identified in four hips, but none of the lesions were more than two millimeters in diameter. None of the acetabular components migrated, and no radiolucent line of more than two millimeters in thickness was seen around any acetabular cup. The data from this study, in which the minimum duration of follow-up was six years, indicate that the anatomically designed prosthesis can provide good results, with low prevalences of pain in the thigh and loosening of the component, in younger, active patients.

Wrist arthroplasty with the trispherical total wrist prosthesis

The clinical results and long-term implant survival of wrist arthroplasty with the Trispherical total wrist prosthesis was evaluated in patients with inflammatory arthritis. Using the Hospital for Special Surgery wrist scoring system, the clinical evaluation of 35 Trispherical total wrist arthroplasties showed an excellent result in 20, good result in 8, fair result in 3, poor result in 2, and failed result requiring revision in 2 wrists at an average follow-up of 9 years. Cumulative implant survival in 67 consecutive Trispherical total wrist arthroplasties was 97% at 5 years and 93% at 10 and 12 years postoperatively. Patient satisfaction with wrist arthroplasty using the Trispherical prosthesis was excellent. We attribute the favorable long-term results obtained with the use of this prosthesis to its inherent design that allows for accurate restoration of the center of rotation of the wrist.

Fretting corrosion accelerates crevice corrosion of modular hip tapers

The use of multiple-component systems in orthopedic surgery gives the surgeon increased flexibility in choosing the optimal implant, but introduces the possibility of interfacial corrosion. Such corrosion could limit the longevity of prostheses due either to tissue reactions to corrosion products, or to device failure. The incidence and nature of corrosion of modular total hips was evaluated in a consecutive series of 79 retrieved implants from University Hospitals of Cleveland. Surfaces were examined with stereo- and scanning electron microscopy. Several laboratory studies were undertaken to examine mechanisms that might contribute to the initiation of corrosion. The first set of experiments investigated the effect of head neck extension; the second study looked at the effect of material combinations on fretting corrosion and crevice corrosion. Analysis of retrieved implants demonstrated that fretting corrosion played a major role in the initiation of interface corrosion, and that a correlation existed between corrosion and length of neck extensions. Laboratory studies showed that longer head neck extensions may be more susceptible to fretting corrosion because of an instability at the interface. Short-term mixed-metal corrosion studies demonstrated that the coupling of cobalt and titanium alloys did not render the interface more susceptible to corrosion. It is hypothesized that fretting corrosion contributes to the initiation of modular interface corrosion, and that the problem can be reduced by design changes that increase the stability of the interface.

Primary semiconstrained total elbow arthroplasty. Survival analysis of 113 consecutive cases

We used survival analysis to evaluate 113 consecutive semiconstrained total elbow arthroplasties (TEAs) in 95 patients at a maximum follow-up of 99 months. Our criteria for failure were mechanical malfunction, revision for any reason, and deep infection. The primary diagnosis was inflammatory arthritis in 86 elbows, post-traumatic arthritis in 6, supracondylar nonunion or fracture in 12, osteoarthritis in 2 and other causes in 3. Seven failures were due to deep infection, and five of these had a primary diagnosis of inflammatory arthritis. Eight failures were revised or had revision recommended for aseptic loosening, and six of these were in patients with post-traumatic arthritis or supracondylar nonunion. The cumulative survival for TEAs performed for post-traumatic arthritis, fractures or supracondylar nonunion was 73% at three years and 53% at five years, significantly worse than the cumulative three- and five-year survivals of 92% and 90%, respectively, for patients with inflammatory arthritis. TEA with a semiconstrained prosthesis appears to have a satisfactory survival in selected patients with arthritic disorders. The incidence of deep infection was reduced by improvements in surgical technique and postoperative management, and the routine use of antibiotic-impregnated cement. The incidence of aseptic loosening was low, except in patients with supracondylar nonunion or post-traumatic arthritis.

Primary semiconstrained total elbow arthroplasty. Survival analysis of 113 consecutive cases

We used survival analysis to evaluate 113 consecutive semiconstrained total elbow arthroplasties (TEAs) in 95 patients at a maximum follow-up of 99 months. Our criteria for failure were mechanical malfunction, revision for any reason, and deep infection. The primary diagnosis was inflammatory arthritis in 86 elbows, post-traumatic arthritis in 6, supracondylar nonunion or fracture in 12, osteoarthritis in 2 and other causes in 3. Seven failures were due to deep infection, and five of these had a primary diagnosis of inflammatory arthritis. Eight failures were revised or had revision recommended for aseptic loosening, and six of these were in patients with post-traumatic arthritis or supracondylar nonunion. The cumulative survival for TEAs performed for post-traumatic arthritis, fractures or supracondylar nonunion was 73% at three years and 53% at five years, significantly worse than the cumulative three- and five-year survivals of 92% and 90%, respectively, for patients with inflammatory arthritis. TEA with a semiconstrained prosthesis appears to have a satisfactory survival in selected patients with arthritic disorders. The incidence of deep infection was reduced by improvements in surgical technique and postoperative management, and the routine use of antibiotic-impregnated cement. The incidence of aseptic loosening was low, except in patients with supracondylar nonunion or post-traumatic arthritis.

Vascular ultrasonography for deep venous thrombosis after total knee arthroplasty

Screening vascular ultrasonography was performed postoperatively on 164 consecutive patients being treated with total knee arthroplasty (203 total knee prostheses). This consisted of examination of the femoral and popliteal veins of the operative extremity with color flow and duplex ultrasonography one week postoperatively. All patients received deep venous thrombosis (DVT) prophylaxis with sequential compressive pneumatic stockings, low-dose warfarin, continuous passive motion, and early mobilization. All patients were observed prospectively for thromboembolic sequelae for a minimum of six months postoperatively. The screening study was significantly limited in six (3%) of the 203 total knee prostheses. The overall incidence of sonographically detected proximal DVT or symptomatic calf vein thrombosis was 3% (6/203), and the incidence of symptomatic pulmonary embolism was 2% (4/203). Four of the ten thromboembolic complications occurred after hospital discharge. Results of this study suggest that duplex ultrasonography can be a useful screening method for identification of venous thrombosis after TKA. Patients with asymptomatic proximal DVT can be identified and appropriately treated before development of serious thromboembolic complications. Routine screening for DVT after TKA can avoid the considerable expense, inconvenience, and potential risk of complications associated with prolonged postoperative prophylactic anticoagulation. The combination of sequential compressive stockings, early mobilization, and low-dose warfarin appears to be a safe and effective prophylactic regimen against venous thromboembolic disease in these high-risk patients.

Distal femoral replacement with allograft/prosthetic reconstruction for treatment of supracondylar fractures in patients with total knee arthroplasty

Large-segment distal femoral allografts were used in conjunction with non-linked total knee prostheses to reconstruct bone deficits following supracondylar fracture of the femur in seven patients with previous total knee arthroplasties. Three patients with multiple medical problems died of unrelated causes prior to a minimum 2 year follow-up. Indications for surgery were previously failed attempts at osteosynthesis and significant fracture comminution, osteopenia, and intercondylar extension or femoral component loosening. Specifics of the surgical technique included subperiosteal excision of the involved distal femur with retention of a soft tissue sleeve containing the collateral ligaments and reconstruction with a large-segment allograft and a stemmed, semiconstrained total knee prosthesis. Cement fixation using pressurized technique with intramedullary plugging of the tibial and femoral canal was routinely used to secure the prosthesis/allograft construct to the host bone. Postoperative complications included one dislocation, which was successfully treated closed, and one popliteal artery injury, which was successfully repaired. There were no postoperative infections. Two patients, however, had some degree of persistent instability, warranting bracing at the time of last follow-up. Using the Knee Society rating system, the average knee score for these patients was 71, and the average pain score and function score were 33 and 49, respectively. Range of motion averaged 96 degrees. All of the femoral components were well fixed at last follow-up. Results of this study indicate that large-segment distal femoral allografts used in conjunction with nonlinked knee prostheses can be an acceptable method of treatment of these difficult reconstructive problems.

Custom total shoulder arthroplasty in inflammatory arthritis. Preliminary results

Twenty-three patients with inflammatory arthritis and rotator cuff deficiency have undergone 27 custom-fit total shoulder arthroplasties. The design used included a short-stem humeral component and a metal-backed glenoid component with an offset keel. The glenoid component was custom-fit to provide maximum coverage of the glenoid surface. The average age of the patients at the time of surgery was 55 years (range, 20-75 years). All patients had inflammatory arthritis, 16 were on steroids, and all had some degree of rotator cuff involvement ranging from small to complete tears. The average length of follow-up study was 5 years (range, 3-7 years). The average preoperative shoulder score was 36 points (range, 15-50 points) with an average pain score of 7 (of 30) points. Postoperatively, the shoulder score improved to 85 points with a pain score of 28 points. Twenty-one shoulders scored a good to excellent result. Two patients required reoperation, both for recurrent rotator cuff tears, one of which occurred after a fall. Radiographic analysis revealed no incidence of humeral radiolucency and six cases of glenoid radiolucency. Only two of these were progressive and both were associated with irreparable rotator cuff tears. Thus, in the early follow-up, this design of glenoid has decreased the incidence of glenoid radiolucency in this difficult patient population.

Use of an antibiotic impregnated polymethyl methacrylate intramedullary spacer for complicated revision total hip arthroplasty

Revision total hip arthroplasty is frequently necessary in the presence of significant proximal femoral bone loss, periprosthetic fracture, or infection. In these situations, optimal reconstruction may sometimes warrant the use of special implants, including bone grafts. The emergent presentation of these cases or unexpected findings at the time of surgery can preclude the use of these treatment options. In cases of periprosthetic sepsis, delayed reimplantation may be the most successful approach to eradicate infection. In seven of these complicated revision total hip arthroplasties, the authors used an antibiotic-impregnated intramedullary polymethyl methacrylate spacer with delayed prosthetic reimplantation to allow for the use of these methods. Benefits of this technique include uncompromised radiographic evaluation of the proximal femur for design of a custom implant, if needed, stabilization of the proximal femur facilitating early mobilization of the patient in the case of periprosthetic fracture, and local delivery of antibiotics to the wound in the case of infection. The author's ability to reconstruct these total hip arthroplasties complicated by bone deficiency, fracture, and sepsis, was significantly improved with this use of this technique.

"Hybrid" total knee arthroplasty with the Miller-Galante prosthesis. A prospective clinical and roentgenographic evaluation

Twenty-nine "hybrid" Miller-Galante total knee arthroplasties, in 22 patients, were evaluated prospectively and according to the clinical and roentgenographic guidelines of The Knee Society. Selection of this technique, incorporating an uncemented, porous-ingrowth femoral component and a cemented tibial component, was based on patient age, medical condition, activity level, and intraoperative assessment of bone quality and ligament competency. The average age of the patients at the time of surgery was 71 years. The average preoperative Knee Society Knee Score was 32; average pain score was 14; and the average function score, 47. After an average follow-up interval of 28 months postsurgery (minimum, 24 months), the average Knee Society Knee Score was 93; the average pain score, 47; and the average function score, 79. Range of motion averaged 110 degrees. Only one knee, with persistent pain of obscure origin, rated an unsuccessful result. No arthroplasties were revised for any reason. Twenty-three knees had fluoroscopically guided roentgenograms to assess the bone-prosthesis and bone-cement interfaces. No significant or progressive radiolucencies were noted under any of the components. No apparent adverse bone remodeling was associated with the uncemented femoral component. The fluoroscopically guided roentgenograms were significantly more sensitive in detecting interface radiolucencies than plain ones. Clinical and roentgenographic evidence of component loosening were absent in all patients. Results of this study suggest that the hybrid fixation technique can reliably provide satisfactory pain relief and restoration of function in properly selected patients. Potential advantages of an uncemented femoral component include decreased operative time, reduction of polyethylene wear from cement debris, and avoidance of a possible adverse biologic response to polymethylmethacrylate.

Bending properties of wire-reinforced bone cement for applications in spinal fixation

PMMA beam specimens were tested in four-point bending to determine if the bending strength of acrylic bone cement, as used in posterior spinal fusion, could be improved by metal-wire reinforcement. The result showed that the load-carrying capacities of 1- and 0.5-mm diam stainless-steel-wire-reinforced PMMA specimens in bending were significantly higher than similar unreinforced normal PMMA samples. On an average, steel reinforcement comprising approximately 1% of the cross-sectional area of the PMMA specimens caused a 15% increase in bending strength. Even after the cement fractured, the reinforcing wires still sustained an appreciable amount of bending moment, thus preventing catastrophic failure of cement alone.