Edward J. McPherson

Periprosthetic total hip infection: outcomes using a staging system.

The outcomes of 50 consecutive patients with chronic periprosthetic total hip arthroplasty infections were evaluated based on a staging system developed at the authors’ institution. The staging system includes three categories: infection type (acute versus chronic), systemic host grade, and local extremity grade. The initial treatment plan was a two-stage resection followed by reimplantation if clinically indicated. Treatment was modified for each patient according to how the patient responded to initial debridement. The average followup was 23.2 months (range, 0–74 months). Of the 50 patients, 29 had reimplantation with a total hip arthroplasty (58%), 17 patients had permanent resections (34%), and four patients had amputations (8%). Five patients died (10%). Fifteen patients had muscle flap transfers into the hip for soft tissue coverage. Significant correlations were seen with the staging system and outcome parameters. Patients who were very medically ill were far more likely to die or have their leg amputated. Conversely, healthier patients were more likely to have successful reimplantation. A strong correlation was seen with a compromised local wound and the need for muscle flap transfer. Complication rates were strongly related to worsening medical condition and a worsening local wound. Based on these results, a staging system for periprosthetic infection is a useful tool that with additional refinement will provide more objective evaluation of treatment methods for periprosthetic hip infection in the future.

Rehabilitation after total knee arthroplasty : A comparison of 2 rehabilitation techniques

This study was conducted to compare postoperative total knee arthroplasty rehabilitation protocols. The hypothesis of this study was that patients undergoing total knee arthroplasty could achieve range of motion and hospital discharge in the same period using a postoperative rehabilitation protocol that did not use a continuous passive motion machine. This randomized prospective study compared 46 total knee arthroplasties in which a continuous passive motion machine was used with 37 total knees that were rehabilitated with early passive flexion of the knee (named drop and dangle protocol). Postoperative physical therapy regimens were otherwise the same for both groups. Surgical technique was the same for both groups except for closure which was performed in the drop and dangle group with the knee at 90 ° to 95 ° flexion. Only patients with osteoarthritis were included in the study, and in both groups of patients received the same prosthetic components. Patients in the drop and dangle group were discharged from the hospital 1 day earlier (p = 0.01) and had a statistically better extension range of 2.8 ° at 6 months (p = 0.03). Knees in the drop and dangle group had less drainage (p = 0.06). Range of motion and hospital discharge can be achieved in a similar time interval with the drop and dangle technique as with using a continuous passive motion device, and that such a device is not required for postoperative knee rehabilitation.

Hydroxyapatite-coated proximal ingrowth femoral stems. A matched pair control study.

A matched pair study of 2 groups of 42 uncemented total hip replacements were compared retrospectively after a minimum 3-year followup. Forty-two hips were implanted with a hydroxyapatite coating on the proximal femoral patched porous surfaces; 42 hips had patched porous-coated stems without hydroxyapatite. There were no clinical differences between the matched groups by any criteria of measurement. There was no statistically significant difference between the matched groups for femoral stem fixation at all followup intervals. At the 3-year followup, 90% of the femoral stems in the hydroxyapatite porous group, and 83% in the porous control group achieved stable bony fixation. Hydroxyapatite-coated femoral stems demonstrated accelerated bone remodeling characterized by proximal cancellous hypertrophy. The percentage of femoral stems exhibiting cancellous hypertrophy was significantly greater at all followup intervals. This study did not demonstrate any clinical advantage of hydroxyapatite being added to a porous-coated surface. The radiographic changes of bone remodeling seen with hydroxyapatite are not known to improve durability of the hip arthroplasty. This study again condemns the use of patched porous-coating and titanium-bearing surfaces.

Medialization of the patella in total knee arthroplasty.

Patellar complications of total knee arthroplasty remain the most common cause of pain and reoperation. Laboratory studies have suggested that medialization of the patella will improve tracking of the patella on the trochlea of the femoral component. The purpose of this study was to determine if clinical medialization of the patellar component on the patellar bone would improve tracking of the patella as demonstrated radiographically. Sixty-two knees were randomized so that 31 knees had a centrally placed patellar component and 31 had the patellar component placed on the medial two thirds of the patellar bone. There was no difference between the two groups with respect to either clinical or radiographic results in the first year after surgery. There was no improvement compared with previous reports in the incidence of tilt and displacement. The one improvement was a reduction in the incidence of lateral release. Thus, consequences of lateral release such as postoperative morbidity, avascular necrosis of the patella, and stress fracture of the patella can be avoided. It is recommended that the patellar component be placed on the medial two thirds of the patella to reduce the occurrence of lateral release. Tracking of the patella during surgery can be assessed using a single suture placed at the superior pole of the patella, and this technique in combination with the no-thumbs test provides an additional means of evaluation for patellar tracking.

Infected total knee arthroplasty. Two-stage reimplantation with a gastrocnemius rotational flap.

This study reviews a consecutive series of 21 patients undergoing two-stage reimplantation total knee arthroplasty for late chronic infection. All 21 patients had late chronic infections, and 20 of 21 patients were compromised hosts. Seven different organisms were isolated at the time of prosthetic resection. Staphylococcus coagulase negative species was the most frequently isolated organism. At the time of reimplantation, a medial gastrocnemius rotational flap was rotated over the proximal tibia and knee for wound closure. The average explantation time was 25 weeks (range, 7–76 weeks), and no methylmethacrylate spacers were used. At an average 17-month followup (range, 5.1–33.1 months) all reimplanted total knee replacements remained in place with one patient having recurrent infection. At reimplantation, 11 patients had positive bacterial cultures from tissue specimens. Sixteen of the 33 (40%) positive cultures were from specimens taken from the medullary canal. At followup, the average Knee Society Score was 77.4 (range, 40–100). The lack of a methylmethacrylate spacer and a long explanation time were considered important factors in diminishing functional performance and determining the need for a gastrocnemius flap. A medial gastrocnemius rotational flap should be considered at the time of reimplantation total knee arthroplasty if the soft tissue envelope about the knee is compromised and cannot be closed without undue tension.

Effects of radiofrequency energy on human articular cartilage: an analysis of 5 systems.

Background Previous radiofrequency work has not rigidly controlled energy application to the articular cartilage, giving uncertain results published to date. Hypothesis At minimal settings, radiofrequency probes cause cell death in measurable areas when applied to human articular cartilage. Study Design Controlled laboratory study. Methods Simulating operating room conditions, 5 commercially available radiofrequency probes were attached to a customized jig to standardize a minimal contact pressure of each probe tip to 2.0 g. Keeping all variables the same, probes were placed on specific points of fresh grade II human cartilage with treatment times of 1 and 3 seconds at the manufacturers recommended settings. Grade III cartilage was also tested with a treatment time of 3 seconds, and grade II cartilage was studied with the probe held 1 mm off the cartilage surface. Cartilage was blindly analyzed by confocal microscopy using a live/dead cell viability assay to determine the extent of cell death. Results Radiofrequency probes produced significant cellular death in the form of a half-circle into the cartilage to variable depths. For treatment times of 1 and 3 seconds, cell death measurements ranged from 404 to 539 μm and 1034 to 1283 μm, respectively. One probe failed to show any effect, with minimal evidence of cell death or cartilage smoothing. When probes were kept a 1.0-mm distance above the cartilage, no cell death or cartilage smoothing was noted. Radiofrequency treatment of grade III cartilage penetrated to the subchondral bone. There was no statistically significant difference between the damage caused by monopolar and bipolar probes when tested under these rigidly controlled conditions. Conclusion These results showed significant cellular death at these minimal conditions to the underlying chondrocytes with radiofrequency probes. Surgeons using this technology need to be aware of the power and dangerous potential these probes can have on articular cartilage.

Breakage of a Total Condylar III Knee Prosthesis A Case Report

The authors report the failure of a Total Condylar III (Cintor, Johnson and Johnson, Raynham, MA) knee arthroplasty, implanted in a second revision knee surgery, due to fracture of the tibial spine. The tibial component was in varus position and externally rotated relative to the tibia. This imparted torque and resulted in a spiral fracture of the polyethylene spine. This is the first report of failure of a Total Condylar III prosthesis by mechanical breakage.

Contemporary total hip replacement with metal on metal articulation.

Between 1991 and 1994, 74 patients received total hip replacements with metal on metal articulation. The results of these patients with 74 hips who had a 6-month to 4-year (average, 2.2 years average) followup are reported. Patients were prospectively evaluated by the Harris hip score, a patient self assessment form, and radiographs. The average postoperative Harris hip score was 91. Patient self assessment forms showed that 95% of the patients scored their results as excellent or good. No patient had revision for loosening, but 1 underwent revision surgery for recurrent dislocation. Serial radiographs have not revealed loosening or osteolysis. Wear could not be measured radiographically. Twenty-seven of the patients had bilateral total hip replacements with 1 hip being metal on polyethylene; the patients could not detect any difference between the 2 hips. The satisfactory short term results from the contemporary metal on metal articulation investigated in this study are encouraging and warrant continued study.

Muscle flaps in total knee arthroplasty.

The results of 12 patients who had been treated with muscle flap coverage for compromised soft tissues associated with total knee arthroplasty were studied. Five latissimus dorsi free flaps, 6 medial gastrocnemius rotational flaps, and 2 rectus abdominis free flaps were done in 12 knees. The authors used and classified 3 types of muscle flaps: (1) prophylactic soft tissue coverage, done before definitive reconstruction; (2) treating muscle flap for infected prostheses with deficient soft tissue coverage; and (3) salvage muscle flap for wound dehiscence or necrosis in the immediate postoperative period. These patients were observed for an average of 4.1 years (range, 1–8 years). The wound was revascular-ized successfully in 100% of the knees. The prosthesis was preserved in 83% of the knees. Recurrent infection occurred in 3 patients. Treating muscle flaps are least likely to result in an overall successful reconstruction because these flaps are used in knees with chronic infection. Prophylactic flaps and salvage muscle flaps provide the soft tissue coverage necessary to allow successful reconstruction in the appropriate circumstances.

Anatomic assessment of the proper insertion site for a tibial intramedullary nail.

Objectives: To locate the proper insertion point for a tibial intramedullary nail in the coronal plane. Design: Fifty‐seven cadaveric lower legs were disarticulated at the knee and ankle and stripped of their soft tissue. Each tibia was nailed in a retrograde fashion through the center of the tibial plafond with a seven‐millimeter sharp‐tipped rod through the proximal tibia. The exit point of the nail was measured in the coronal plane in relation to the tibial tubercle. Results: Except for one tibia, the intramedullary nail exit point was always located medial to the center of the tibial tubercle with the average being eight millimeters ± six millimeters medial to the center of the tibial tubercle. Forty‐six percent of the nails exited medial to the whole tibial tubercle. Conclusions: The insertion point of a tibial nail should be over the medial aspect of the tibial tubercle in the coronal plane. Our data supports using a medial or patellar splitting approach for nail insertion. Insertion sites lateral to the tibial tubercle should be avoided.