A new model to assess tibial fixation. II. Concurrent histologic and biomechanical observations

A tibial hemiarthroplasty model was designed to allow concurrent histologic and biomechanical analysis of the tibial implant-bone interface. In this study, micromotion was visually observed at the implant-bone interface of cemented and uncemented implants. Six dogs had staged bilateral implantation. Biomechanical analysis of three- and 12-month specimens was correlated with histologic analysis of the same specimen. Load transmission involved compression of trabecular bone and fibrous tissue at the interface. Failure of the interface occurred through cyclic fatigue and microfracture of trabeculae. Micromotion was seen at all interfaces, porous or smooth, cemented or uncemented. Displacement was greatest under an eccentrically loaded plateau. Micromotion at ingrown and cemented interfaces was because of trabecular compression. Uncemented smooth devices and uncemented porous devices with fibrous fixation of the plateau appeared unstable. The cemented implants and a single uncemented implant studied at 12 months showed no interface micromovement. The absence of micromovement in the uncemented implant was associated with subsidence and with ingrowth of 30% into the porous peg and porous plateau.     

Patellar prosthesis positioning in total knee arthroplasty. A roentgenographic study

Patellar prosthesis positioning in 40 primary total knee replacements was evaluated with regard to (1) patellar tilt, (2) angle between the patellar component and patellar bony remnant, (3) lateral versus medial placement, (4) patellar height, and (5) size of the patellar component versus patellar length. Two different designs were evaluated. Twenty knees that were resurfaced with a patellar button prosthesis and implanted with conventional surgical technique constituted Group A. Twenty knees that were resurfaced with a new biconvex prosthesis and implanted with specially designed instrumentation constituted Group B. For Group A, the patellar tilt averaged 4.25 degrees preoperative and 8.35 degrees postoperative. For Group B the patellar tilt averaged 4.60 degrees preoperative and 1.83 degrees postoperative. In Group B, there was significant improvement in patellar position, with only two patients showing values exceeding the neutral range (p = 0.0409). The angle between the patellar component and the bony remnant in Group A averaged 5.975 degrees, and in Group B, 1.447 degrees. Two patients in Group A and 18 patients in Group B had values in the normal range for patellar tilt and the angle between the prosthesis and the bone. The prosthesis was inserted medial to the patellar center in six patients in Group A and one patient in Group B. A significant decrease in patellar height was noted for both groups, but values were still within the normal range. Both groups showed significant increase in the postoperative articular length, indicating that oversized prostheses were inserted and excess bone removed.     

Ceramic coating improves tibial component fixation in total knee arthroplasty

Forty uncemented total knee arthroplasties (36 patients) were randomly allocated to a Miller-Galante II prosthesis with or without hydroxyapatite/tricalcium phosphate (HA/TCP) coating on the titanium fiber mesh on the undersurface of the tibial component. The patients were followed for 2 years with repeated radiostereometric examinations. After 2 years, the HA/TCP tibial components displayed smaller anterior-posterior tilt and less subsidence. The mean value of maximal total point motion was small: 0.5 mm in both groups. At 24 months, there were more radiolucent lines under the tibial tray and around the stem in the uncoated group, but the clinical results did not differ. HA/TCP coating on the undersurface of the tibial component improved the stability and seemed to improve the quality of the interface between the tibial component and the bone.     

A new surgical technique for tibial tubercle transfer in total knee arthroplasty.

Several methods are described for extensor mechanism realignment in total knee arthroplasty, including lateral release, medial reefing, V-Y quadricepsplasty, and tibial tubercle transfer. Each has its indications, merits, and pitfalls. The advantages of tibial tubercle transfer include precise realignment of the quadriceps mechanism, the ability to properly locate the patella proximally or distally, and maintenance of quadriceps power. The authors present a new technique for tibial tubercle transfer in total knee arthroplasty. Important points include (1) full-thickness medial and lateral soft tissue flaps that are anchored to bone and cover the transferred tubercle at the end of the procedure; (2) osteotomy of a long (10-cm) strip of tubercle and tibial crest; (3) placement of the osteotomized segment in a prepared, inset cancellous bone bed; and (4) fixation of the graft with multiple staples that hold the graft in place without being inserted through the graft. The method described will allow surgeons to perform tibial tubercle transfer reproducibly while avoiding the frequently cited complications of nonunion, loss of fixation, and wound slough.     

A method of tack fixation of tibial bone grafts in total knee arthroplasty

A simple and secure method of bone graft fixation using a tack is described for reconstruction of peripheral tibial defects during cemented and uncemented total knee arthroplasties. In use since 1985, this method facilitates minimization of tibial bone resection and provides an intrinsically stable platform for tibial component seating. This method is technically simple to perform with routine primary total knee arthroplasty equipment and is especially helpful for intermediate-sized grafts, which are too small to be handled conveniently with screws.     

ICLH knee arthroplasty. A consecutive study of 108 knees with uncemented tibial component fixation

One hundred eight ICLH knee arthroplasties with cementless tibial component fixation were performed from 1978 through 1982 in Gothenburg, Sweden. The patients were followed for 2-8 years (mean, 4 years) with clinical and radiographic examinations at regular intervals, and the data were computer-analyzed. Patellar subluxation-dislocation, often accompanied by pain, occurred in 50% of the knees. Eleven arthroplasties failed due to aseptic loosening. Survival rate analysis performed using three different definitions of failure resulted in cumulative success rates after 8 years of 86%, 78%, and 72%. Most failures occurred between 2 and 5 years after surgery. Patients with bilateral arthritis were overrepresented among the failures. There was a significant correlation between failure and poor bone sclerosis around the polyethylene pegs. Most patients can be treated with cementless fixation, but other types of fixation should be considered for elderly patients and patients with severe bilateral disease.     

Survivorship of cementless total knee arthroplasty without tibial plateau screw fixation

Seventy-two cementless tricompartmental total knee arthroplasties were performed in 47 patients using a porous-coated prosthesis without screw fixation for the tibial components between 1984 and 1986. These individuals were observed at regular intervals for a minimum of three years. Their Hospital for Special Surgery pain and function scores as well as roentgenographic signs of anatomic alignment and subsidence were evaluated at six months, one year, and three years postoperatively. The roentgenographic evaluation for subsidence looked at a measurable difference in the anteroposterior roentgenograph on the medial and lateral plateaus and on the lateral roentgenograph anteriorly and posteriorly. Early postoperative interpretations have suggested pain and knee scores to be much lower than scores in the cemented prosthesis. Reassessment after three years, however, revealed no further deterioration of the noncemented prosthesis in respect to knee scores and survival analysis. Roentgenographic analysis showed no correlation between subsidence and alignment alterations, subsidence and time, or subsidence and pain. It appears that after an initial period of discomfort, the noncemented knee can achieve a functional, clinical, and roentgenographic result much better than previously anticipated. The consequences beyond this time period still remain unknown.     

Midterm results of all-polyethylene tibial components in primary total knee arthroplasty

Our goal was to determine the 7-year survivorship of a total knee arthroplasty system with all-polyethylene tibial components. From June 1996 to December 1997, 129 consecutive patients (177 knees) (>/=70 years old) underwent such primary arthroplasty at 2 centers in the United States. The 88 patients (120 knees) with 7 years or more of follow-up were evaluated radiographically and functionally. Average results included: Knee Society Score, 93.7 points (SD, 8.1); Knee Society function score, 68.9 points (SD, 27.6); range of motion, 119 degrees (SD, 10.9); osteolysis, 0%; stress shielding, 6.6%; progressive radiolucencies, 2.5%; Kaplan-Meier survivorship (revision), 99.4% (95% confidence intervals, 98.2%-100.0%). At midterm follow-up, an all-polyethylene tibial component proved to be an excellent surgical option for total knee arthroplasty in an elderly patient population.     

Mid-term results of total knee arthroplasty after high tibial osteotomy

Background The outcome of total knee arthroplasty (TKA) after high tibial osteotomy (HTO) is still controversial. In order to determine if osteotomy has any effect on this outcome we performed a medium-term review of a cohort of patients with knee osteoarthritis. Materials and methods Thirty-two patients (38 knees), who were treated with a HTO before the TKA during the last 8 years, were compared with a matched group who underwent primary TKA. The knees were evaluated preoperatively and postoperatively according to the scoring systems of the Knee Society and Hospital for Special Surgery (HSS). The anteroposterior tibiofemoral alignment, the Insall–Salvati patellar position ratio, range-of-motion and the location of the lateral joint line, were also recorded. The patients were reviewed with a mean follow-up of 4.5 years after TKA. Results The preoperative and postoperative knee scores had no statistically significant differences between the two groups. So was the case with the intraoperative releases, blood loss, thromboembolic or neurologic complications and infection rates in either group. Access to perform the arthroplasty was reportedly more difficult and took an average of 25 min longer. A significant difference (p < 0.05) was detected in terms of impingement of the tibial stem on the lateral tibial cortex, patellar subluxation and patella baja between the two groups but this did not have any influence on the outcome of the prosthesis. Knee alignment and stability so as range of motion (ROM) measurements were also found with no statistical significance. Conclusion Although we did manage to detect statistically significant differences mainly in radiographic results between the two groups, this situation did not appear to influence the clinical outcome of the patients, however. The fact that most of the patients had good or excellent results at an average follow-up of 4.5 years suggests that HTO does not have a significant negative effect on later TKA.     

OAK knee evaluation. A new way to assess knee ligament injuries

The Orthop?dische Arbeitsgruppe Knie (OAK) documentation is based on clinical evaluation during functional knee stability testing near extension and near flexion. Increased compartmental translations and rotations, which result from structural defects because of anatomic lesions in a given knee injury, are clinically evaluated. The synopsis of the clinically detectable abnormal knee motion is graphically documented. A clinically applicable grading system of the true and reversed pivot shift phenomena completes the assessment of compartmental knee instability. Important contributing factors such as the constitutional laxity, the morphotype, and the range of motion are registered on the documentation form. The evaluation form presents four categories that represent subjective, objective, and functional criteria reflecting the overall results of repaired ligaments. This evaluation format establishes selected criteria to compare results from different centers.     

Long-term results of total knee arthroplasty following high tibial osteotomy according to Wagner

Purpose  

There is relatively little information available about the long-term results of total knee arthroplasty (TKA) following high tibial osteotomy. The aim of our study was to share our experiences and long-term results of TKA after a previous closing wedge high tibial osteotomy according to Wagner.     

Initial stability of tibial components in primary knee arthroplasty. A cadaver study comparing cemented and cementless fixation techniques

The purpose of this roentgen stereophotogrammetric analysis (RSA) study was to evaluate the initial stability of cemented and cementless tibial components in vitro. Twenty tibia specimens were matched into two groups. In the first group, the tibial trays were cemented superficially and in the second group cementless fixation with stem and screws was performed. An axial load of 2000 N for 1000 and 10,000 cycles was applied onto the specimens and RSA was performed. The experimental results after 1000 cycles showed a higher migration with significant differences for the parameters maximum lift off (p = 0.011) and maximum total point motion (p = 0.002) in the cementless group. After 10,000 cycles, the migration in the cementless group increased significantly for maximum lift off (p = 0.043), maximum subsidence (p = 0.045) and maximum total point motion (p = 0.013). The higher migration rates in the cementless group demonstrate a lower initial mechanical stability of cementless tibial components which can cause an early component loosening.     

Hydroxyapatite-coated tibial implants compared with cemented tibial fixation in primary total knee arthroplasty. A randomized trial of outcomes at five years

BACKGROUND: Although excellent long-term results have been reported with cemented tibial fixation, cementless fixation as a means to improve the longevity of total knee prostheses continues to be of interest to clinicians. The purpose of this study was to compare outcomes between cementless tibial fixation with hydroxyapatite and cemented tibial fixation in the first five years following primary total knee arthroplasty. METHODS: We performed a prospective, randomized clinical trial that included eighty-one patients with noninflammatory knee arthritis who underwent primary total knee arthroplasty when they were less than seventy years of age. The subjects were randomized at the time of surgery to be treated with either cementless tibial fixation with hydroxyapatite or cemented tibial fixation. Evaluations were performed preoperatively and at six months, one year, and five years postoperatively by a physical therapist who was blinded to group allocation. Self-reported pain and function, the primary outcomes, were measured with the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and the RAND 36-Item Health Survey (RAND-36). Complications and revision rates were determined through a review of hospital records and at each patient evaluation. The Knee Society radiographic score was used to evaluate plain radiographs at each assessment. RESULTS: Seventy subjects (86%) completed the five-year assessment. Slightly more pain was reported in the hydroxyapatite group at six months as measured with both the WOMAC and the RAND-36, a difference that disappeared by one year postoperatively. No differences were seen in function, radiographic findings, or complications. No subject required revision of the tibial prosthesis during the study. CONCLUSIONS: At five years postoperatively, there is no difference between cementless tibial fixation with hydroxyapatite and cemented tibial fixation in terms of self-reported pain, function, health-related quality of life, postoperative complications, or radiographic scores.     

Radiolucency adjacent to the tibial component in total knee arthroplasty.

This study determined the accuracy of standard radiographs in observing radiolucency adjacent to the tibial component in total knee arthroplasty. A model of the proximal tibia was used. Plastic sleeves of different heights were glued under the tibial tray to imitate radiolucency. By tilting the x-ray tube 1degrees at a time, an investigation was performed to determine how many degrees it would take to cover the heights of the different plastic sleeves. In a clinical study of patients at standard follow-up, 21 knees were examined using standard radiographs. Radiographs using image intensification were then taken of the same knees to obtain radiographs with views parallel to the plane of the tibial tray. The results of the study on the phantom showed that a 1degrees deviation of the x-ray beam from the optimal position would obscure a 0.5-mm "radiolucency." This was true for radiolucencies of 2, 3, 4, and 5 mm. This was confirmed in the clinical study where < or = 4 mm of radiolucency was obscured on standard radiographs. Therefore, standard radiographs cannot be used to determine radiolucency. The 2-mm radiolucency normally associated with loosening is not clinically valid.     

Stability of initial fixation of the tibial component in cementless total knee arthroplasty

This study measured the vertical displacement of three kinds of cementless tibial components [Porous Coated Anatomical (PCA), Tricon, and Whiteside], under eccentric loading up to 2,225 N. Displacement between the tibial tray and the proximal tibia was measured with linear variable differential transformers at the anterior and posterior side when anteriorly or posteriorly loaded, and at the medial and lateral side when medially or laterally loaded. The general pattern of motion was sinking at the loaded side and lift-off at the opposite side. Lift-off opposite the loaded side was fairly small for all components at all measurement sites. Among the three components, the Whiteside showed the smallest displacements. The Tricon (when anteriorly or posteriorly loaded), and the PCA (when medially or laterally loaded) showed sinking at the loaded side. Anterior screw fixation of the PCA was not effective in preventing anterior lift-off. The tilting motion of the tibial components observed in this study implies instability of the initial fixation, which could possibly compromise bony ingrowth. Furthermore, this tilting could cause uneven distribution of load, and potentially result in fracture of the underlying bone.     

Autologous bone grafting without screw fixation for tibial defects in total knee arthroplasty

We evaluated 30 knees with autologous bone grafts, performed without screw fixation, for tibial defects in total knee arthroplasty (TKA). The tibial defects were classified into three types: contained, flat peripheral, and slant peripheral. The resected femoral condyle was fixed with a combination of bone cement and the tibial component, without using screws. The patients were followed for an average of 6 years and 10 months. In all knees except 1, the grafted bone united and formed good continuity with the tibial floor. Autologous bone grafting without screw fixation is a simple and effective method to deal with the tibial defects in primary TKA, especially for contained and flat peripheral defects. Received: November 24, 2000 / Accepted: June 25, 2001     

The results of tibial tubercle osteotomy for revision total knee arthroplasty

Tibial tubercle osteotomy was used in the surgical exposure of 67 knees in 64 patients undergoing revision total knee arthroplasty. The clinical and radiographic results were reviewed retrospectively. The mean follow-up time was 30 months (range, 5-60 months). Knee Society scores (KSS) confirmed good or excellent results in 87% of the knees, and the mean KSS was 86. The procedure was particularly effective in 2-stage exchanges for infected total knee arthroplasty, in which infection was eradicated in 9 of 10 cases, with a mean KSS of 82. In this series, no patellofemoral complications, no component malalignments, and no avulsions of the patellar tendon occurred. Serious complications directly related to the tibial tubercle osteotomy occurred in 5 patients (7%).     

Proximal tibial osteotomy. A new fixation device

A new internal fixation device was applied to 41 proximal tibial osteotomies to ensure against loss of postoperative correction. An oblique osteotomy was stabilized by two screws and a five-hole one-half tubular plate. Thirty-six patients with 41 proximal tibial osteotomies were reviewed for an average roentgenographic follow-up time of 22.6 months (range, six to 48 months) with no loss of correction. In addition, 16 patients with 19 osteotomies and a minimum clinical follow-up time of two years were reviewed using the Hospital for Special Surgery knee scoring system; these early results demonstrated a similar outcome to previously published series. The new fixation device is simple to use, permits early postoperative motion, and maintains the exact correction obtained at the time of surgery.