Edwin P. Su

Revision of metal-on-metal resurfacing arthroplasty of the hip: THE INFLUENCE OF MALPOSITIONING OF THE COMPONENTS

We have reviewed 42 patients who had revision of metal-on-metal resurfacing procedures, mostly because of problems with the acetabular component. The revisions were carried out a mean of 26.2 months (1 to 76) after the initial operation and most of the patients (30) were female. Malpositioning of the acetabular component resulted in 27 revisions, mostly because of excessive abduction (mean 69.9 degrees ; 56 degrees to 98 degrees ) or insufficient or excessive anteversion. Seven patients had more than one reason for revision. The mean increase in the diameter of the component was 1.8 mm (0 to 4) when exchange was needed. Malpositioning of the components was associated with metallosis and a high level of serum ions. The results of revision of the femoral component to a component with a modular head were excellent, but four patients had dislocation after revision and four required a further revision.

The role of constrained liners in total hip arthroplasty.

Recurrent instability after total hip replacement is a complex problem with extensive literature detailing multiple etiologies and solutions. It has been shown that the success of surgical treatment depends on the identification of the cause. Unfortunately, in certain situations, there may not be an optimal solution for dealing with the cause, or the cause may remain unidentified. In these cases, the success rate of surgical treatment of the unstable total hip replacement is only 40% to 50%. Constrained acetabular liners were developed to address the problem of recurrent instability by holding the femoral head captive within the socket. Before the use of constrained liners, there were no reliable solutions to dislocation arising from inadequate soft tissues, a deficient abductor mechanism, or neuromuscular disorders. We have used a constrained liner for these situations, with poor patient compliance and instability without a clear cause as relative indications for its use. Our experience with attaining joint stability using one type of constrained liner has resulted in a 97.6% success rate (83 of 85 hips) at 4.8 years, surpassing the outcomes achieved by other means. The intermediate followup after implantation of a constrained liner has not shown significant rates of component wear or loosening.

Imaging of Metal-On-Metal Hip Resurfacing

Conventional radiography is the primary imaging modality to evaluate the condition of hip resurfacing implants and the preferred method of assessing implant stability over time. Radiographs assess the angle of inclination of the femoral and acetabular components, implant stability, and femoral neck narrowing. Ultrasonography detects solid or soft tissue masses adjacent to the implant. Magnetic resonance imaging (MRI) detects osteolysis and complications in the periprosthetic soft tissues such as wear-induced synovitis, periprosthetic collections, neurovascular compression, and quality of the muscle and tendons of the rotator cuff of the hip. For pain after hip resurfacing, early use of optimized MRI is recommended.

Operative treatment of tibial plateau fractures in patients older than 55 years.

Surgical treatment of tibial plateau fractures in the older patient poses an additional challenge because of the underlying condition of the bone and articular surface. We sought to identify risk factors for poorer outcomes in the operative treatment of displaced tibial plateau fractures in older patients. Thirty-nine displaced tibial plateau fractures in patients 55 years and older were treated operatively. Patients were evaluated objectively with Rasmussen clinical and radiologic scoring techniques, and the Short Musculoskeletal Function Assessment and the Short-Form 36 self-assessment instruments. The Rasmussen clinical and radiologic scoring systems, used on average 2.54 years postoperatively, found acceptable results in 87.2% and 82.1% of patients, respectively. The fracture classification of Schatzker was not predictive of results. External fixation was associated with significantly poorer results. Increasing age was associated with poorer clinical and self-assessment scores, although preexisting degenerative joint disease was not. The results from the Short-Form 36 indices were not significantly worse for our study patients. The average Short Musculoskeletal Function Assessment score of our study patients indicated poorer function for mobility than a normative group. Operative treatment of this injury in this population can result in favorable outcomes as evaluated by clinical, radiographic, and self-assessment criteria.

A prospective, multi-center, randomised trial to evaluate the efficacy of a cryopneumatic device on total knee arthroplasty recovery

Pain, swelling and inflammation are expected during the recovery from total knee arthroplasty (TKA) surgery. The severity of these factors and how a patient copes with them may determine the ultimate outcome of a TKA. Cryotherapy and compression are frequently used modalities to mitigate these commonly experienced sequelae. However, their effect on range of motion, functional testing, and narcotic consumption has not been well-studied. A prospective, multi-center, randomised trial was conducted to evaluate the effect of a cryopneumatic device on post-operative TKA recovery. Patients were randomised to treatment with a cryopneumatic device or ice with static compression. A total of 280 patients were enrolled at 11 international sites. Both treatments were initiated within three hours post-operation and used at least four times per day for two weeks. The cryopneumatic device was titrated for cooling and pressure by the patient to their comfort level. Patients were evaluated by physical therapists blinded to the treatment arm. Range of motion (ROM), knee girth, six minute walk test (6MWT) and timed up and go test (TUG) were measured pre-operatively, two- and six-weeks post-operatively. A visual analog pain score and narcotic consumption was also measured post-operatively. At two weeks post-operatively, both the treatment and control groups had diminished ROM and function compared to pre-operatively. Both groups had increased knee girth compared to pre- operatively. There was no significant difference in ROM, 6MWT, TUG, or knee girth between the 2 groups. We did find a significantly lower amount of narcotic consumption (509 mg morphine equivalents) in the treatment group compared with the control group (680 mg morphine equivalents) at up to two weeks postop, when the cryopneumatic device was being used (p < 0.05). Between two and six weeks, there was no difference in the total amount of narcotics consumed between the two groups. At six weeks, there was a trend toward a greater distance walked in the 6MWT in the treatment group (29.4 meters versus 7.9 meters, p = 0.13). There was a significant difference in the satisfaction scores of patients with their cooling regimen, with greater satisfaction in the treatment group (p < 0.0001). There was no difference in ROM, TUG, VAS, or knee girth at six weeks. There was no difference in adverse events or compliance between the two groups. A cryopneumatic device used after TKA appeared to decrease the need for narcotic medication from hospital discharge to 2 weeks post-operatively. There was also a trend toward a greater distance walked in the 6MWT. Patient satisfaction with the cryopneumatic cooling regimen was significantly higher than with the control treatment.

Stiffness after TKR: how to avoid repeat surgery.

Stiffness after total knee replacement (TKR) is a frustrating complication that has many possible causes. Although the definition of stiffness has changed over the years, most would agree that flexion <75° and a 15° lack of extension constitutes stiffness. The management of this potentially unsatisfying situation begins preoperatively with guidance of the patients expectations; it is well-known that preoperative stiffness is strongly correlated with postoperative lack of motion. At the time of surgery, osteophytes must be removed and the components properly sized and aligned and rotated. Soft tissue balancing must be attained in both the flexion/extension and varus/valgus planes. One must avoid overstuffing the tibiofemoral and/or patellofemoral compartments with an inadequate bone resection. Despite these surgical measures and adequate pain control and rehabilitation, certain patients will continue to frustrate our best efforts. These patients likely have a biological predisposition for formation of scar tissue. Other potential causes for the stiff TKR include complex regional pain syndrome or joint infection. Close follow-up of a patients progress is crucial for the success in return of range of motion. Should motion plateau early in the recovery phase, the patient should be evaluated for manipulation under anesthesia. The results of reoperations for a stiff TKR are variable due to the multiple etiologies. A clear cause of stiffness such as component malposition, malrotation, or overstuffing of the joint has a greater chance of regaining motion than arthrofibrosis without a clear cause. Although surgical treatment with open arthrolysis, isolated component, or complete revision can be used to improve TKR motion, results have been variable and additional procedures are often necessary.

Comparison of Bone Removed During Total Hip Arthroplasty With a Resurfacing or Conventional Femoral Component: A Cadaveric Study

We sought to examine the amount of bone removed during total hip arthroplasty with a resurfacing femoral component, compared to with a conventional, stemmed femoral component, by using 6 male and 4 female cadaveric pelves with attached bilateral proximal femora. Using randomized assignment and order, a total hip arthroplasty with a resurfacing femoral implant was performed on one side, and total hip arthroplasty with a cementless, stemmed femoral implant was performed on the contralateral side. The relationship between native femoral head diameter and the implanted acetabular socket was on average within 2 mm for both procedures. No significant difference was observed in the amount of acetabular bone removed (9.8 g for hip resurfacing vs 8.8 g). However, a resurfacing component resulted in approximated 3 x less bone removal from the femur (25.8 g vs 75.1 g). This study shows that the preservation of femoral bone with a resurfacing femoral component does not result in an increased removal of acetabular bone when compared to the use of a conventional, stemmed femoral component.

Ceramic Liner Fractures Presenting as Squeaking After Primary Total Hip Arthroplasty

BACKGROUND Squeaking after ceramic-on-ceramic total hip arthroplasty is a relatively uncommon phenomenon. It usually does not require treatment in the absence of pain, mechanical symptoms, and/or relentless squeaking. The purpose of this investigation was to report on four patients who presented with hip pain and squeaking due to fractured ceramic liners after ceramic-on-ceramic total hip arthroplasty. METHODS Four patients with painful squeaking after ceramic-on-ceramic total hip arthroplasty were seen at our institution. One patient had a revision for suspected loosening and excessive anteversion of the cup noted on radiographs and magnetic resonance imaging (MRI). The remaining three patients had a revision for audible squeaking with progressive pain. RESULTS Intraoperatively, the ceramic liners of all four patients were fractured. CONCLUSIONS Squeaking after ceramic-on-ceramic total hip arthroplasty rarely is a functional issue. However, painful squeaking without notable trauma may indicate fracture of the ceramic liner. Painful squeaking is difficult to evaluate by conventional imaging. When painful squeaking occurs, exploration via surgical revision is recommended in selected patients, as ceramic liner fractures may go unnoticed on radiographs and/or MRI and thus their actual prevalence may be higher than estimated.

Aseptic Lymphocyte Dominated Vasculitis-Associated Lesion Resulting From Trunnion Corrosion in a Cobalt-Chrome Unipolar Hemiarthroplasty

Most of the published descriptions of adverse soft tissue reactions that have been reported in the context of a metal-on-metal articulation have been in cases of total hip arthroplasty or resurfacing arthroplasty. Recently, several case reports have been published describing aseptic lymphocyte dominated vasculitis-associated lesions (ALVAL) in metal-on-polyethylene. To our knowledge, there has not been a description of a similar, aggressive reaction secondary to metal debris from the head-neck junction of a unipolar hemiarthroplasty component. In this case report, we describe a patient with a catastrophic failure of a unipolar hip hemiarthroplasty, secondary to aggressive osteolysis and an inflammatory mediated immunological reaction to metal debris.

Fixed flexion deformity and total knee arthroplasty

Fixed flexion deformities are common in osteoarthritic knees that are indicated for total knee arthroplasty. The lack of full extension at the knee results in a greater force of quadriceps contracture and energy expenditure. It also results in slower walking velocity and abnormal gait mechanics, overloading the contralateral limb. Residual flexion contractures after TKA have been associated with poorer functional scores and outcomes. Although some flexion contractures may resolve with time after surgery, a substantial percentage will become permanent. Therefore, it is essential to correct fixed flexion deformities at the time of TKA, and be vigilant in the post-operative course to maintain the correction. Surgical techniques to address pre-operative flexion contractures include: adequate bone resection, ligament releases, removal of posterior osteophytes, and posterior capsular releases. Post-operatively, extension can be maintained with focused physiotherapy, a specially modified continuous passive motion machine, a contralateral heel lift, and splinting.