David A. McQueen

Knee Arthrodesis with the Wichita Fusion Nail: An Outcome Comparision

The Wichita Fusion Nail® (WFN®) is a knee arthrodesis stabilization system that employs compression via an intramedullary rod. It was designed for use in the salvage of the irretrievably failed total knee arthroplasty and other severe knee pathologies. Questionnaires covering the fusion success rate, fusion time, and complication rate were obtained from 33 surgeons who were among the first to use the device. Data from these questionnaires were analyzed to determine if the rate of successful fusion was close to 100%, which was the primary hypothesis of this study. The average time required to achieve fusion and the rate of complications were also calculated and compared to similar results available in the literature. The results for 44 selected patients were included and it was determined that all achieved fusion for a success rate of 100%. This compared favorably with reported success rates in the range of 54% to 96%. The average fusion time was 15.5 weeks. Complications included: six delayed unions, three deep infections, and two periimplant fractures for a major complications rate of 20.4%. Both the fusion times and complication rate compared favorably with other reported results. Surgeons using the device for the first time had outcomes equal to those of more experienced users. Our results demonstrated that a rate of successful arthrodesis close to 100% could be consistently achieved with the WFN.® Overall, the WFN® facilitated an improved outcome for a previously difficult procedure.Level of Evidence: Therapeutic study, level IV (case series). See the Guidelines for Authors for a complete description of level of evidence.

Salvage procedures for failed total knee arthroplasty

Revision total knee arthroplasty for aseptic loosening or following infection can pose formidable challenges to the reconstructive surgeon. In some cases, the patient will undergo a series of operations, each resulting in ever-increasing bone loss. In extreme circumstances, the end result may be amputation, arthrodesis, or permanent resection arthroplasty. Isiklar et al.1, in a study of amputation following total knee arthroplasty, found that patients had undergone an average of six operative procedures prior to having an amputation. In a review of patients who had a reinfection following reimplantation for an infection at the site of a total knee arthroplasty, Hanssen et al.2 found that patients had undergone an average of thirteen operative procedures. Although amputation or permanent resection arthroplasty results in a poor outcome that can be avoided in most patients, situations in which these options should be considered include life-threatening infection, persistent infection, irreparable soft-tissue deficiency, severe bone loss, and the wishes of the patient following multiple failed attempts at reconstruction. Resection arthroplasty may be best tolerated by patients who are willing to accept loss of ambulation, such as those who are already disabled because of multiple joint involvement. The prevalence of amputation following total knee arthroplasty has ranged from 0.02% to 0.18%, but it has been reported to be 6% in patients with a chronic infection at the site of a total knee arthroplasty1,3-5. The outcome of amputation or resection arthroplasty following total knee arthroplasty is predictably poor, with a low likelihood of ambulation. Isiklar et al.1 reported on a series of nine above-the-knee amputations in eight patients. The mean interval between the first total knee arthroplasty and the amputation was 9.7 years. Eight of the nine amputations were performed for infection with severe bone loss, and one …

Current Status of Revision Total Knee Arthroplasty: How Do We Assess Results?

Failure of primary total knee arthroplasty within five years after the operation most frequently occurs because of deep infection (38%), instability (27%), failure of bone ingrowth into a cementless implant (13%), patellar problems (8%), wear (7%), loosening (3%), or miscellaneous problems (4%)1. In contrast, in a series of 427 revision total knee arthroplasties, failure of fixation was the most frequent problem, followed by abnormal alignment, component malposition, osseous fracture, and patellar problems2. The results of revision total knee arthroplasty are difficult to assess because they are influenced by many factors: the etiology of failure, the extent of bone loss, the quality of the soft tissues, the technique of reconstruction, the adequacy of rehabilitation, patient compliance, the duration of follow-up, and the mode of assessment. Contemporary modular designs have provided good short-term results. A combined review of 161 revisions that had been performed with a modular constrained condylar knee or posterior stabilized design revealed an 80% rate of good or excellent results after an average duration of follow-up of 3.5 years, with a 33% prevalence of radiolucent lines and a 10% rate of complications3. The durability of the results will depend in part on the integrity of the locking mechanisms of the modular components, the quality of the polyethylene, and the load transfer conferred by modular stems and augments to the implants. Long-term studies will be necessary to determine if these modular designs are more durable than nonmodular prostheses. Successful revision total knee arthroplasty requires careful preoperative analysis and planning to ensure that the cause of failure is known and that the necessary instruments, implants, and other supplementary reconstructive materials are available. In 1995, 243,919 primary total knee arthroplasties and 169,803 primary total hip arthroplasties were performed in the United States4. As a …

Negative pressure intrusion cementing technique for total knee arthroplasty.

Negative pressure intrusion (NPI) is an alternative cementing technique for the tibial baseplate of total knee arthroplasty that uses a suction cannula in the proximal tibia to remove excess fluids and fat before cementing. This technique was compared with standard third-generation positive pressure intrusion (PPI) techniques in an in vitro implantation and analysis of 6 pairs of cadaveric tibiae. Six matched pairs of fresh frozen tibiae were prepared by cutting the tibial surfaces, standard cleaning and surface drying, then performing PPI and NPI on 1 of each pair. No objective differences were noted on radiographs or direct cement depth measurement analysis. Scanning electron micrograph evaluation revealed that the PPI specimens had consistently more voids in the cement-bone composite, and the NPI specimens had consistently narrower empty spaces between bone and cement, resulting in tighter fill in NPI specimens. NPI was shown to enhance characteristics known to improve tensile and shear strength in cement-bone composites.

Effect of Bone Block Removal and Patellar Prosthesis on Stresses in the Human Patella

Thermoelastic stress analysis was used to examine stresses on the anterior surface of patellae after patellar bone block excision for autogenous graft anterior cru ciate ligament reconstruction. Complications of anterior cruciate ligament injury often lead to degenerative changes in the knee that can require total knee joint replacement. It was hypothesized that stresses in a bone block-compromised patella may be increased even further by insertion of a patellar prosthesis. All pa tellae were first tested intact and then were retested after a sequence of surgical modifications including pa tellar prosthesis implantation, tapered bone block ex cision, square bone block excision, and both shapes of excised bone blocks with a patellar prosthesis in place. Stresses in patellae with bone blocks excised were sig nificantly greater than stresses in intact patellae. The anterior surface stress pattern in the loaded patella was significantly altered by excision of a bone block. There were no significant differences between maximum stress in patellae with tapered and square bone blocks excised. A finite element analysis showed that excision of a larger trapezoid-shaped bone block greatly in creased maximum stress levels. Insertion of a patellar prosthesis did not significantly alter stress patterns or maximum stress levels in the patella.

Polymethylmethacrylate and titanium alloy particles activate peripheral monocytes during periprosthetic inflammation and osteolysis

We investigated the interactions of particulate PMMA or titanium alloy, patient blood monocytes, and periprosthetic tissues using a SCID‐hu model of aseptic loosening. Periprosthetic tissues and bone chips obtained at revision surgery for loosening were transplanted into muscles of SCID mice. Peripheral blood monocytes (PBMCs) isolated from the same donors were fluorescently labeled and co‐cultured with PMMA or Ti‐6Al‐4V particles before intraperitoneal injection. Control mice with periprosthetic tissue or non‐inflammatory ligament xenografts received naive PBMCs transfusion. Mice were euthanized 2 weeks after PBMC transfusion. The human tissues were well accepted in SCID mice. Transfused fluorescent‐labeled PBMCs were markedly accumulated in transplanted periprosthetic tissues. Multinucleated osteoclast‐like cells were commonly seen within retrieved xenograft tissue, and focal bone erosions were ubiquitous. Total cell densities and CD68+ cells within the xenograft were significantly increased in mice transfused with PMMA and Ti‐provoked PBMCs compared to the naïve PBMC animals (p < 0.05). Immunohistochemical staining identified much stronger positive IL‐1 and TNF stains in xenografts from either PMMA or Ti‐stimulated monocytes transfusion groups (p < 0.05). TRAP+ cells were found around bone chips in both activated‐PBMCs groups, although markedly more aggregated TRAP+ cells in the PMMA‐challenged group than in the titanium group (p < 0.05). MicroCT assessment confirmed the significant decrease of bone mineral density in chips interacted with activated‐monocytes/osteoclasts. In conclusion, PMMA or titanium particles readily activate peripheral monocytes and promote the cell trafficking to the debris‐containing prosthetic tissues. Particles‐provoked PBMCs participated in and promoted the local inflammatory process, osteoclastogenesis, and bone resorption.

Using self-assessed health to predict patient outcomes after total knee replacement

Self-assessed health status has been shown to be a powerful predictor of mortality, service use, and total cost of medical care treatment. We investigated the potential for self-assessed health to further serve as a predictor of improvement in health status after a clinical intervention. Using the five-category measure of self-assessed health (excellent, very good, good, fair, or poor), we examined patients’ improvements in health status after total knee arthroplasty in each of the WOMAC-defined categories for health status in patients. The results indicate that the greater patients rated their preoperative health, the greater their postoperative improvement. The results suggest that a simple process of asking patients to rate their own health in a presurgery clinic could be a powerful tool in predicting patient outcome. This also suggests that by stratifying preoperative self-assessed health, potential improvements in health status will be more fully captured.

Flexion-extension gap in cruciate-retaining versus posterior-stabilized total knee arthroplasty: a cadaveric study.

We re‐examined experimental model results using half‐body specimens with intact extensor mechanisms and navigation to evaluate cruciate‐retaining (CR) and posterior stabilized (PS) total knee arthroplasty (TKA) component gaps through an entire range of motion. Six sequential testing regimens were conducted with the knee intact, with a CR TKA in place, and with a PS TKA in place, with and without 22 N traction in place at each stage. Each of 10 knees was taken through six full ranges of motion from 0° to 120° at every stage using a navigated knee system to record component gapping. No significant difference was found between loaded and unloaded component gaps, and no significant differences were found in component gapping between CR and PS TKAs throughout a full range of motion. Flexion–extension gap measurements were significantly different from previously published data (at 90° flexion). No difference was found in kinematics when comparing CR and PS TKA component designs. Our results suggest that intact extensor mechanisms may be required to perform proper kinematic studies of TKA. Our findings provide evidence that the extensor mechanism may play a major role in the flexion–extension gaps in cadaveric knees.

Single-use instrumentation, cutting blocks, and trials decrease contamination during total knee arthroplasty: a prospective comparison of navigated and nonnavigated cases.

The purpose of this prospective controlled trial was to determine whether decrease in contamination could be achieved in nonnavigated and navigated total knee arthroplasties by replacing traditional saws, cutting blocks, and trials with specialized saws and single-use cutting blocks and trials. Various tray wrapping metrics during total knee arthroplasty were measured in 400 procedures performed by 8 different surgeons at 6 institutions. Instrumentation contamination was determined by counting the number of tray sterility indicators, pans, and instruments that were compromised. The results show that a decrease in contamination was evident in 57% (nonnavigated) and 32% (navigated) fewer compromises of tray sterility indicators, pans, and instruments. Single-use instruments show promising benefits, but further study is needed to confirm safety and efficacy before they can be widely adopted. The authors believe that the use of single-use instruments, cutting guides, and trial implants for total knee arthroplasty will play an increasing role in decreasing operating room contamination and potential deep infections.

The influence of sequential debridement in total knee arthroplasty on the flexion axis of the knee using computer-aided navigation

The effects of osteophyte debridement, bony cuts, and soft tissue releases on the functional flexion axis of the knee can be assessed by evaluating 3D kinematics following each step of a total knee arthroplasty. Using a navigated knee system with dedicated software, the functional flexion axis (helical axis) can be determined after each step. Five paired fresh‐frozen cadaveric knees were used with a CT scan performed on each specimen identifying implanted fiducial markers. Kinematics data were recorded during each step of sequential osseous cuts and soft tissue releases for both an unloaded and loaded limb by each of three surgeons. The functional helical (flexion/extension) axis was identified for all specimens. The internal/external rotation angle (θ) of the helical axis differed from the transepicondylar axis by −8.3° to +6.7° for the unloaded condition. θ ranged from −7.2° to +7.4° with distraction. Soft tissue releases had no effect on θ; until a bony cut of the articular surface, which increased θ from −0.3° to +9.7°. Implantation of cruciate retaining prosthetic components subsequently reduced the θ range −7.3° to +4.0°. Thus, soft tissue releases had minimal effect on θ of the helical axis except for resection of the proximal tibia. Implantation of the CR prosthesis reduced è close to that of the intact knee. In a minority of knees, the helical axis did not coincide exactly with the transepicondylar axis. Interspecimen and left/right variability of θ were significant, although interinvestigator variability and an applied distraction force were insignificant.