R. Michael Meneghini

Results of Unicompartmental Knee Arthroplasty at a Minimum of Ten Years of Follow-up

BACKGROUND There is a renewed interest in unicompartmental knee arthroplasty. The present report describes the minimum ten-year results associated with a unicompartmental knee arthroplasty design that is in current use. METHODS Sixty-two consecutive unicompartmental knee arthroplasties that were performed with cemented modular Miller-Galante implants in fifty-one patients were studied prospectively both clinically and radiographically. All patients had isolated unicompartmental disease without patellofemoral symptoms. No patient was lost to follow-up. Thirteen patients (thirteen knees) died after less than ten years of follow-up, leaving thirty-eight patients (forty-nine knees) with a minimum of ten years of follow-up. The average duration of follow-up was twelve years. RESULTS The mean Hospital for Special Surgery knee score improved from 55 points preoperatively to 92 points at the time of the final follow-up. Thirty-nine knees (80%) had an excellent result, six (12%) had a good result, and four (8%) had a fair result. At the time of the final follow-up, thirty-nine knees (80%) had flexion to at least 120 degrees . Two patients (two knees) with well-fixed components underwent revision to total knee arthroplasty, at seven and eleven years, because of progression of patellofemoral arthritis. At the time of the final follow-up, no component was loose radiographically and there was no evidence of periprosthetic osteolysis. Radiographic evidence of progressive loss of joint space was observed in the opposite compartment of nine knees (18%) and in the patellofemoral space of seven knees (14%). Kaplan-Meier analysis revealed a survival rate of 98.0% +/- 2.0% at ten years and of 95.7% +/- 4.3% at thirteen years, with revision or radiographic loosening as the end point. The survival rate was 100% at thirteen years with aseptic loosening as the end point. CONCLUSIONS After a minimum duration of follow-up of ten years, this cemented modular unicompartmental knee design was associated with excellent clinical and radiographic results. Although the ten-year survival rate was excellent, radiographic signs of progression of osteoarthritis in the other compartments continued at a slow rate. With appropriate indications and technique, this unicompartmental knee design can yield excellent results into the beginning of the second decade of use.

Rapid rehabilitation and recovery with minimally invasive total hip arthroplasty.

To assess the potential recovery rate of a minimally invasive total hip replacement technique with minimal soft tissue disruption, an accelerated rehabilitation protocol was implemented with weightbearing as tolerated on the day of surgery. One hundred consecutive patients were enrolled in this prospective study. Ninety-seven patients (97%) met all the inpatient physical therapy goals required for discharge to home on the day of surgery; 100% of patients achieved these goals within 23 hours of surgery. Outpatient therapy was initiated in 9% of patients immediately, 62% of patients by 1 week, and all patients by 2 weeks. The mean time to discontinued use of crutches, discontinued use of narcotic pain medications, and resumed driving was 6 days postoperatively. The mean time to return to work was 8 days, discontinued use of any assistive device was 9 days, and resumption of all activities of daily living was 10 days. The mean time to walk ½ mile was 16 days. Furthermore, there were no readmissions, no dislocations, and no reoperations. Therefore, a rapid rehabilitation protocol is safe and fulfills the potential benefits of a rapid recovery with minimally invasive total hip arthroplasty.

Adverse Local Tissue Reaction Arising from Corrosion at the Femoral Neck-Body Junction in a Dual-Taper Stem with a Cobalt-Chromium Modular Neck

BACKGROUND Femoral stems with dual-taper modularity were introduced to allow additional options for hip-center restoration independent of femoral fixation in total hip arthroplasty. Despite the increasing availability and use of these femoral stems, concerns exist about potential complications arising from the modular neck-body junction. METHODS This was a multicenter retrospective case series of twelve hips (eleven patients) with adverse local tissue reactions secondary to corrosion at the modular neck-body junction. The cohort included eight women and three men who together had an average age of 60.1 years (range, forty-three to seventy-seven years); all hips were implanted with a titanium-alloy stem and cobalt-chromium-alloy neck. Patients presented with new-onset and increasing pain at a mean of 7.9 months (range, five to thirteen months) following total hip arthroplasty. After serum metal-ion studies and metal artifact reduction sequence (MARS) magnetic resonance imaging (MRI) revealed abnormal results, the patients underwent hip revision at a mean of 15.2 months (range, ten to twenty-three months). Tissue specimens were examined by a single histopathologist, and the retrieved implants were studied with use of light and scanning electron microscopy. RESULTS Serum metal levels demonstrated greater elevation of cobalt (mean, 6.0 ng/mL) than chromium (mean, 0.6 ng/mL) or titanium (mean, 3.4 ng/mL). MRI with use of MARS demonstrated adverse tissue reactions in eight of nine patients in which it was performed. All hips showed large soft-tissue masses and surrounding tissue damage with visible corrosion at the modular femoral neck-body junction. Available histology demonstrated large areas of tissue necrosis in seven of ten cases, while remaining viable capsular tissue showed a dense lymphocytic infiltrate. Microscopic analysis was consistent with fretting and crevice corrosion at the modular neck-body interface. CONCLUSIONS Corrosion at the modular neck-body junction in dual-tapered stems with a modular cobalt-chromium-alloy femoral neck can lead to release of metal ions and debris resulting in local soft-tissue destruction. Adverse local tissue reaction should be considered as a potential cause for new-onset pain in patients with these components, and early revision should be considered given the potentially destructive nature of these reactions. A workup including serologic studies (erythrocyte sedimentation rate and C-reactive protein), serum metal levels, and MARS MRI can be helpful in establishing this diagnosis.

Use of porous tantalum metaphyseal cones for severe tibial bone loss during revision total knee replacement.

BACKGROUND The best treatment method for large tibial bone defects during revision knee replacement has not been established. The purpose of this study was to determine the initial results obtained with a unique reconstructive implant, the porous tantalum metaphyseal cone, designed as an alternative treatment for severe tibial bone loss following total knee arthroplasty. METHODS Porous tantalum metaphyseal cones were implanted during fifteen revision total knee replacements in eight women and seven men who had an average age of 68.1 years at the time of the procedure. The patients had had an average of 3.5 prior total knee replacements. According to the Anderson Orthopaedic Research Institute bone defect classification, eight knees had a Type-3 defect and seven knees had a Type-2B bone defect. All patients were followed clinically and radiographically. RESULTS The patients were followed for an average of thirty-four months (range, twenty-four to forty-seven months). Overall, the average Knee Society clinical scores improved from 52 points preoperatively to 85 points at the time of the final follow-up. At the final follow-up evaluation, all fifteen porous metaphyseal cones showed evidence of osseointegration with reactive osseous trabeculation at points of contact with the tibia. There was no evidence of loosening or migration of any of these tibial reconstructions at the time of final follow-up. CONCLUSIONS At the time of short-term follow-up, the porous tantalum metaphyseal tibial cones effectively provided structural support for the tibial implants in this series. The potential for long-term biologic fixation may provide durability for these tibial reconstructions. Long-term follow-up and comparison with alternative reconstructive techniques will be required to evaluate the true effectiveness of this treatment approach.

Muscle damage during MIS total hip arthroplasty : Smith-Petersen versus posterior approach

Decreased muscle damage is a reported benefit of minimally invasive surgical (MIS) approaches in total hip arthroplasty (THA). We compared the extent and location of muscle damage during THA using the MIS anterior Smith-Peterson and MIS posterior surgical approaches. THA was performed in six human cadavers (12 hips). One hip was assigned to the Smith-Peterson approach and the contralateral hip to the posterior approach. Muscle damage was graded with a technique of visual inspection to calculate a proportion of surface area damage. Less damage occurred in the gluteus minimus muscles and minimus tendon with the Smith-Peterson approach. A mean of 8% of the minimus muscle was damaged via the Smith-Peterson approach, compared to 18% via the posterior approach. The tensor fascia latae muscle was damaged (mean of 31%), as well as direct head of the rectus femoris (mean 12%) during the Smith-Peterson approach. The piriformis or conjoined tendon was transected in 50% of the anterior approaches to mobilize the femur. The posterior approach involved intentional detachment of the piriformis and conjoined tendon and measurable damage to the abductor muscles and gluteus minimus tendon in each specimen. Clinical outcome studies and gait analysis are necessary to ascertain the functional implications of these findings.

Early Failure of Unicompartmental Knee Arthroplasty Leading to Revision

The most common previously reported modes of failure of unicompartmental knee arthroplasty (UKA) in the first and second decades are polyethylene wear, progression of arthritis, and component loosening. The purpose of this study is to describe an early mechanism of failure of the medial UKA. Thirty-two consecutive revisions from UKA to total knee arthroplasty were retrospectively reviewed. The predominant mode of failure observed in 15 (47%) of 32 knees was medial tibial collapse. Of these, 87% were an all-polyethylene design, and 7 of 15 failed in less than 16 months and required more complex reconstruction with stems, augments, and screws and cement. Increased tibial slope was associated with posterior tibial collapse. In our series, knees that failed by medial tibial collapse had more significant bone defects and required more complex reconstructions than is currently reported in the literature.

The progression of patellofemoral arthrosis after medial unicompartmental replacement: results at 11 to 15 years.

This study reports the 11-year to 15-year results of unicompartmental knee arthroplasty with an emphasis on failure mechanisms and progression of patellofemoral arthrosis. In a prospective study of 513 consecutive potential knee replacement candidates, 59 patients (12%) had medial unicompartmental arthroplasty of the knee. All 59 patients had isolated unicompartmental disease without clinical symptoms or radiographic evidence of patellofemoral arthritis. No patient was lost to followup. The average followup was 13 years (range, 11–15 years). The mean preoperative Hospital for Special Surgery knee score of 55 points (range, 30–79 points) improved to a mean of 90 points (range, 60–100 points) at final followup. Patellofemoral symptoms were present in 1.6% of patients at 10 years; this increased markedly to 10% of patients at 15 years (p < 0.01). Four patients (10%) had moderate or severe patellofemoral symptoms at final followup; two were revised to a primary total knee replacement at 7 and 11 years for progressive patellofemoral degeneration. No component was radiographically loose and no osteolysis was seen. The Kaplan-Meier survival with loosening or revision for any reason was 98.0% ± 2.0% at 10 years and 95.7% ± 4.3% at 15 years. At up to 15 years, unicompartmental knee arthroplasty yielded good clinical results; however, progressive patellofemoral arthritis was the primary mode of failure.

Bone Remodeling Around Porous Metal Cementless Acetabular Components

Bone remodeling around cementless acetabular components after total hip arthroplasty has not been well characterized. A randomized, prospective study of total hip arthroplasty was performed comparing 2 cementless acetabular implants: a solid titanium and a more elastic porous tantalum design. Seventeen hips (9 porous tantalum, 8 titanium) underwent quantitative computed tomography at mean of 7.7 years, and adjacent bone mineral density (BMD) was calculated. The absolute and relative decrease in BMD from preoperative level was less in zones 9 to 15 mm adjacent to the porous tantalum compared to the titanium component (P <or= .02) and predominated posterosuperiorly. The relative BMD increased in all regions adjacent to the porous tantalum component from 5% to 40% over the control. This data demonstrates stress-shielding likely occurs less around a highly porous metal implant of material with an elastic modulus similar to bone.

Epinephrine-induced pulmonary edema during arthroscopic knee surgery. A case report.

In recent reports, use of dilute epinephrine irrigation fluid has been recommended as a safe and effective way to improve visualization in arthroscopic knee and shoulder surgery 1,2. We are not aware of any reports, in the orthopaedic literature, of adverse reactions to epinephrine utilized in this manner. The anesthesiology literature contains a single case report of nearly fatal ventricular tachycardia in a patient undergoing shoulder arthroscopy with use of dilute epinephrine irrigation fluid 3. We present a case of nearly fatal cardiopulmonary collapse during arthroscopy of the knee in which dilute epinephrine irrigation fluid was utilized. The patient was informed that data concerning her case would be submitted for publication. A nineteen-year-old female college athlete underwent arthroscopy for reconstruction of the anterior cruciate ligament and transplantation of a medial meniscal allograft to treat chronic knee pain and instability. The patient had no relevant medical history, did not take any medications, and had a normal preoperative hemoglobin level and hematocrit. She had no family or personal history of cardiac, pulmonary, or endocrine abnormalities and no history of adverse reactions to general anesthesia. She stated that she did not use any over-the-counter supplements or medications. General endotracheal anesthesia with midazolam, sufentanil, and propofol was administered uneventfully in the operating room. Inhalation anesthetics were not utilized, and no other medications were administered prior to induction. A pneumatic tourniquet was not used. After administration of 0.25% bupivacaine with epinephrine (1:100,000) in the subcutaneous tissue, standard anteromedial and anterolateral arthroscopic portals were made. The arthroscopy was performed with utilization of a pressure-controlled pump system set at 40 mm Hg for irrigation with a dilute epinephrine solution, with the concentration of epinephrine calculated to be 0.3 mg/L (1.5 mL of 1:1000 [1 mg/mL] epinephrine mixed into 5 L of saline solution). …

A Randomized, Prospective Study of 3 Minimally Invasive Surgical Approaches in Total Hip Arthroplasty: Comprehensive Gait Analysis

Purported advantages of total hip arthroplasty performed with minimally invasive surgical (MIS) approaches are less muscle damage and faster recovery. There are little data scientifically evaluating these claims. Twenty-four consecutive hips were randomized to total hip arthroplasty through 1 of 3 MIS approaches (2-incision, mini-posterior, and mini-anterolateral). Each patient underwent preoperative and postoperative gait analysis. Gait parameters included vertical ground reaction force, velocity, single-leg stance time, limb-loading rate, and abductor torque. All 3 groups demonstrated overall improvements in gait parameters at 6 weeks postoperatively. The anterolateral approach patients showed a decrease in the vertical ground reaction force at mid-stance, whereas the 2-incision and posterior approaches demonstrated no significant change. These results fail to demonstrate any significant advantage of the 2-incision approach over the posterior approach in kinetic gait parameters. Furthermore, the anterolateral approach demonstrates a gait pattern consistent with abductor muscle injury in the early recovery period, despite the MIS approach.