Porous tantalum cones for large metaphyseal tibial defects in revision total knee arthroplasty: a minimum 2-year follow-up

Sixteen cases of revision total knee arthroplasty requiring the use of porous tantalum tibial cones for 2 T2A, 3 T2B, 4 T3A, and 7 T3B tibial bone defects (Anderson Orthopaedic Research Institute classification) after 13 cases of aseptic loosening and 3 cases of staged reimplantation for infection were reviewed. At an average 31 months (24-38), no patients were lost to follow-up. There were 2 cases of recurrent sepsis requiring removal of a well-fixed cone. In the remaining 14 cases, the reconstructions were functioning well with no reoperations. Radiographs demonstrated reestablishment of the joint line, neutral mechanical axis (average, 5.4° of valgus), and signs of stable osteointegration into the cones. Good short-term results were achieved in complex revisions, with these new reconstructive tools.     

Prospective results of uncemented tantalum monoblock tibia in total knee arthroplasty: minimum 5-year follow-up in patients younger than 55 years

A significant increase in younger patients undergoing total knee arthroplasty raises the theoretical concern for revision secondary to micromotion and fixation failure with cemented components. We prospectively studied 100 consecutive tantalum monoblock uncemented tibial components and 312 concurrent cemented controls. Patients younger than 55 years with adequate bone stock were enrolled. This cementless patient group was younger and had higher preoperative functional status. Prostheses were posterior-substituting uncemented femoral and tibial components with a cemented patellar button. Knee Society pain and function scores and radiographs were obtained, and a cost analysis was performed. Knee Society scores were excellent and equivalent beyond 6 months. There was no significant difference in perioperative blood loss, complication rates, or cost. There was a significant decrease in operative time in the uncemented group. Radiographs revealed no failures of ingrowth at last follow-up. There were 3 uncemented group failures, but none were due to failure of fixation. The use of a porous tantalum tibia at minimum 5 years has yielded promising clinical and radiographic results in a younger patient population.     

Preformed articulating knee spacers in 2-stage total knee revision arthroplasty: minimum 2-year follow-up

Two-stage revision arthroplasty using articulating spacers for the treatment of infected total knee arthroplasty (TKA) is a successful management technique. Our purpose was to report our results using preformed, commercially available articulating spacers made of gentamicin-impregnated cement. Thirty-three patients with infected primary or revision TKAs were treated with these spacers using a 2-stage revision technique. In most cases, the spacers were modified intraoperatively by adding a stem of reinforced antibiotic-impregnated acrylic cement. Successful eradication was achieved in 30 of 33 cases at a minimum 2-year follow-up interval. Two patients required a second spacer before successful revision TKA. No spacer fractures or dislocations occurred in this series. No adverse soft tissue effects were noted from the use of this type of articulating spacer.     

Revision surgery for patellar dislocation after primary total knee arthroplasty

This study evaluated risk factors for patellar dislocation after primary total knee arthroplasty and determined functional outcomes in patients following revision. Thirty-nine knees in 39 patients averaging 68 years (range, 27-91 years) at the time of revision were evaluated at a mean of 3.2 years (range, 2-7 years). Mean Knee Society and Function scores significantly improved from 34 and 35 to 77 and 54, respectively. Patellar dislocation most commonly resulted from errors in technique such as soft-tissue imbalance and malaligned components that led to poor tracking of the patella. Patellar tracking only improved after soft-tissue realignment in combination with revision of malaligned or loose components. Although revision significantly improved active knee extension and Knee Scores, two thirds of the patients had residual disabilities and pain.     

Revision total knee arthroplasty with a cemented posterior-stabilized or constrained condylar prosthesis: A minimum 3-year and average 5-year follow-up study

The results of 57 revision total knee arthroplasties performed for aseptic failure between 1984 and 1992 with a cemented posterior-stabilized or constrained condylar prosthesis were reviewed at follow-up examinations at a minimum of 36 and an average of 62 months (range, 36–120 months). The reason for revision was aseptic loosening of 1 or both components in 32 knees (56%), instability in 16 knees (28%), polyethylene wear and osteolysis in 4 knees (7%), supracondylar femur fracture in 2 knees (4%), and a failed allograft, pain, and arthrofibrosis in 1 knee each (5% total). The average age of the patients at the time of the revision was 74 years (range, 38–90), and the original diagnosis for the majority of patients was osteoarthritis (74%). All of the revision prostheses were cemented posterior stabilized or constrained condylar-type implants. Bone deficiencies were grafted with cancellous allograft in contained defects and cortical allograft in noncontained defects. Five knees were reconstructed with allograft-prosthesis composites. The average modified Hospital for Special Surgery knee score improved from 49 to 82 (100 points possible) at final follow-up evaluation (P < 0.001). Seventy-nine percent of knees were graded as good or excellent. Kaplan-Meier survivorship analysis predicted 94% ± 6.2% survival at 40 months and 75% ± 25% at 99 months. There were 4 clinical failures, 3 of which were related to residual instability in patients with a posterior-stabilized prosthesis. Complications (3 knees) were exclusively related to the extensor mechanism. Radiographically, overall knee alignment improved from 0.3° varus to 3.0° valgus. Fifty-six percent of tibial components were placed in slight varus alignment. Radiolucent lines occurred in 33% of knees, but there were no complete or progressive radiolucencies. Radiolucent lines were more prevalent adjacent to press-fit intramedullary femoral stems compared with cemented stems (P < .02), but the difference did not correlate with clinical or radiographic failure. The median bone defect score, as proposed by the Knee Society Committee on Bone Defects, was significantly greater in knees that were revisions of a failed cemented total knee arthroplasty compared with revision of a failed cementless total knee arthroplasty (P = .02) but was not correlated with clinical or radiographic outcome (P> .05).     

Joint line and patellar height restoration after revision total knee arthroplasty

Background:

Restoration of proper joint line (JL) position and patellar height in revision total knee arthroplasty (TKA) is essential in the recovery of knee function and kinematics. We determined whether the JL position and patellar height could be restored in patients undergoing septic and aseptic revision TKA.

Materials and Methods:

We retrospectively reviewed 70 patients (74 knees) who had revision TKA between September 2004 and December 2010. Forty seven knees had a two stage revision for infected TKA and 27 knees for aseptic failure. The JL position, patellar height and patellar tendon (PT) length were measured and compared between primary TKA and post revision. The clinical scores including a hospital for special surgery (HSS), Knee Society Score (KSS), Western Ontario and McMaster Universities (WOMAC) and range of motion (ROM) were compared.

Results:

The overall JL increased from 17.51 mm to 18.37 mm post revision, the Insall-Salvati (IS) ratio declined from 0.98 to 0.92, and the PT length declined from 42.92 mm to 39.45 mm. 9 of the 21 patellar baja knees improved to normal patellar height. After revision, the JL in the septic group (17.02 mm) was significantly lower than the aseptic group (20.74 mm). The changes of the JL position and IS ratio in the septic group were significantly larger than the aseptic groups (P < 0.05). JL position had a positive correlation to the IS ratio and PT length post revision. The knee function scores including HSS, KSS, WOMAC scores, and ROM all improved post revision compared to pre revision (P < 0.05), and the septic group had a lower knee function compared to the aseptic group. JL position and IS ratio post revision had no correlation to the HSS, KSS, WOMAC scores, and ROM.

Conclusions:

JL position can be sufficiently restored with appropriate distal femoral augment reconstruction after revision TKA, but the patellar height cannot be well improved, especially in the septic revision with obvious PT contracture. No correlation was found between the JL position and patellar height to the knee function post revision TKA.     

Dual massive skeletal allograft in revision total knee arthroplasty

The reconstruction of large uncontained defects represents a major challenge to the revision total knee surgeon, and the outcome of the revision often depends on the management of these bone deficiencies. We report the first successful use of both complete distal femoral and proximal tibia massive allografts in the reconstruction of large femoral and tibial uncontained defects during revision total knee arthroplasty. At the five-year follow up, we did not find any infection, graft failure or loosening of implant, in spite of using two massive structural allografts in a single revision total knee arthroplasty.     

Effect of retaining a patellar prosthesis on pain, functional, and satisfaction outcomes after revision total knee arthroplasty

It remains controversial whether patients' pain, function, and satisfaction are affected in revision total knee arthroplasty by patellar prosthetic resurfacing. This is a retrospective, comparative cohort study to evaluate this. One hundred twenty-six patients who underwent total knee arthroplasty revision were identified. After revision, the presence or absence of a patellar prosthesis was ascertained. At a minimum of 2 years' follow-up, pain and function were assessed by Western Ontario and McMaster Universities Osteoarthritis Index, Oxford-12, Short-Form 12, and patient satisfaction questionnaires in 110 patients (58 with patellar component, 52 bony shell). Univariate and multivariate analyses demonstrated no significant difference between the 2 cohorts for Western Ontario and McMaster Universities Osteoarthritis Index pain, function, Oxford-12, and satisfaction outcomes. The absence of a patellar prosthesis does not appear to significantly affect pain, function, or satisfaction outcomes after revision total knee arthroplasty.     

The use of porous metal cones in revision total knee arthroplasty

Massive bone defects represent a major problem in revision total knee arthroplasty. Traditionally, structural allograft has been used for this purpose; however, this is technically demanding and is associated with a failure rate. Metaphyseal tantalum cones have been a major advancement. They have made surgery easier and have yielded better results when compared to reconstruction with allograft. Adding the ability to comfortably use these implants to one’s armamentarium should be a priority for surgeons who regularly revise total knee replacements. These implants have completely replaced the use of structural allografts in the authors’ practice.     

Clinical outcome of revision of the patellar component in total knee arthroplasty. A 2- to 7-year follow-up study

The objectives of this study were to determine the relationship between the thickness of the residual patellar bone and the composite patella-patellar component, and the clinical outcome in patients who had undergone revision total knee arthroplasty (TKA) with a biconvex patellar component. Clinical outcome after at least a 2-year follow-up was determined using the Knee Society pain and functional scores, and radiographically, with the thicknesses of the patellar bone and composite measured in 23 knees (22 patients). The thickness of the patellar bone after preparation for a biconvex patellar component was significantly less for revised patellae (average, 5.0 mm) than the primary patellae (average, 7.9 mm; P < 0.01). Differences in thickness between preoperative patellae, primary composites, and revision composites did not significantly affect postoperative results. There were no patellar fractures, despite the relatively thin bone remnant in the revision patients. Radiolucency was observed in 8% of the revisions. A patella with a thickness of residual bone of as little as 5 mm can provide favorable clinical results in revision TKA with restoration of the composite thickness of the patella achieved using a thick but small-diameter biconvex patellar component. Received for publication on Feb. 4, 1998; accepted on Aug. 20, 1998     

The use of bulk allografts in revision knee arthroplasty

During the revision of a failed total knee implant, when large osseous defects are encountered, the surgeon has the following three options for managing severe bone loss: revision with a custom implant, revision with a rotating-hinge component, or reconstruction with an allograft and a long-stemmed revision component. An allograft reconstruction replaces the damaged bone, albeit with dead bone; whereas the other two options require additional bone to be removed. By using a bone defect classification system preoperatively, the surgeon estimates the extent of bone damage and orders the proper revision system and allograft material. A durable revision arthroplasty is achieved by using long-stemmed implants that provide axial stability, cementless stems that permit compressive loads, and step cuts that achieve rotational stability.     

Secondary patellar resurfacing in total knee arthroplasty: results of multivariate analysis in two case-matched groups

Although patellofemoral symptoms after patellar-retaining knee arthroplasty are common, no evidence has been published in the literature on the potential benefit from patellar resurfacing at a later stage. This study evaluates the effect of secondary (delayed) patellar resurfacing using comparisons between 2 case-matched groups of patients with primary and secondary patellar resurfacing. Furthermore, multivariate statistical methods were applied to study factors that may influence the final outcome. Our results suggest that although significant clinical improvement was seen after delayed patella resurfacing, the outcome of secondary patellar resurfacing is inferior to that expected for a similar group of patients with primary resurfacing. Furthermore, the timing (delay period) of the secondary resurfacing procedure appears to negatively affect the final outcome. This suggests that secondary patellar resurfacing, when indicated, should be considered at an early stage.     

Scintigraphic assessment of patellar viability in total knee arthroplasty after lateral release

To what extent lateral retinacular release done in total knee arthroplasty compromises patellar viability has been debated. This study is a prospective study to assess patellar viability using Technetium-99m methylene diphosphate (Tc-99m MDP) scintigraphy. Between 2005 and 2006, 59 patients (72 knees) who underwent primary total knee arthroplasty were studied, of which 36 required lateral release. All patients underwent regional bone scan using Tc-99m MDP before and 1 to 3 weeks after the surgery. Two nuclear medicine consultants using both qualitative and quantitative assessment interpreted the scans independently. Fourteen knees with lateral release showed scintigraphic signs of hypovascularity in the early postoperative period that normalized in 8-week postoperative period. This study documents the greater incidence of transient patellar hypovascularity associated with lateral release.     

Preliminary results of an uncemented trabecular metal tibial component in total knee arthroplasty

Trabecular metal has several theoretical advantages for the long-term survival of a tibial component. We report the results of a prospective cohort of 105 consecutive primary total knee arthroplasties using an uncemented trabecular metal (tantalum) tibial component at a minimum 3-year follow-up (range, 36-56 months). There was a significant improvement in Oxford Knee scores and Short Form-12 scores postoperatively. There was no radiolucency at the implant-bone interface on any postoperative radiograph. There has been one (1%) revision of the tibial component for trauma. The 3-year results using this prosthesis are as good as those published for the commonly used cemented prostheses. Longer follow-up is required to see whether these results are maintained over time.     

Rotational alignment in total knee arthroplasty

Total knee arthroplasty is a successful procedure for end-stage knee osteoarthritis, demonstrating a 10-year survival rate of 92–98%. Rotational alignment of components affects the kinematics of the tibiofemoral and patellofemoral joints and the longevity of the implant. Reliable references for rotation for the femoral component are the transepicondylar axis and the Whiteside line (AP Axis), while a reliable reference for tibial baseplate rotation is the tibial tubercle. Assessing rotation postoperatively requires a CT scan. Revision for malrotation has proven to be successful for isolated component or combined component malrotation, yielding improvements in range of motion and Knee Society Scores.     

Hybrid component fixation in total knee arthroplasty: minimum of 10-year follow-up study

Hybrid total knee arthroplasty (TKA) (uncemented femur with cemented tibia and patella) was introduced in the late 1980s to gain the theoretical advantage of durable cementless femoral fixation while avoiding the problems noted with cementless tibial fixation. From December 1992 to July 2000, 215 patients (235 knees) who underwent hybrid TKA were enrolled in this study. Five types of prosthesis (AGC, Maxim, LCS-M, LCS-APG, and Scorpio) were used. Revision rate for aseptic loosening was 16 (6.8%) of 235 knees. At 10 and 15 years, survivorship with tibial or femoral revision as the end point was 0.95 and 0.92, respectively. Hybrid TKA provides durable fixation with clinical and radiographic performance at minimum 10 years comparable with cemented series.     

Evaluation of a porous tantalum uncemented acetabular cup in revision total hip arthroplasty: clinical and radiological results of 60 hips

Long-term survival of the acetabular component in revision total hip arthroplasty (THA) is determined by initial implant stability and bone ingrowth. Highly porous Trabecular Metal (TM, Zimmer, Inc, Warsaw, Ind) facilitates ingrowth and may be an ideal material for revision THA. The outcome and survivorship of a TM, nonmodular, uncemented acetabular cup were assessed in 60 consecutive patients undergoing revision THA (mean follow-up, 42 months; range, 14-68 months). Most (55/60) acetabular cups were implanted without screw fixation. Mean Harris Hips Scores improved from 74.8 preoperatively to 94.4 at last follow-up. Serial radiographs demonstrated excellent bone apposition and bone graft incorporation. Complications were limited to 7 cases of dislocation and 1 revision for aseptic loosening. The TM acetabular cup appears suitable for use in revision THA and warrants further study.     

Isolated revision of failed metal-backed patellar components: outcome with minimum 4-year follow-up

Several reports document high failure rates of metal-backed patellar components, but few report the outcome of revising these components to all-polyethylene, cemented implants. At a mean 87.2-month follow-up, we describe a series of 36 patients (40 knees) who underwent isolated metal-backed patellar revision to a cemented, all-polyethylene patellar component. After the patellar revision, 5 patients (6 knees) underwent additional surgery, but no patellar components required revision. The additional surgeries were performed at an average of 77.6 months after patellar revision and included 3 tibial insert exchanges for polyethylene wear, 2 revisions of femoral and tibial components for osteolysis, and 1 realignment procedure for recurrent subluxation of the patella. We conclude that revision of a failed metal-backed patellar component to a cemented, all-polyethylene patella is a durable, successful procedure.     

The effect of an augmentation patella prosthesis versus patelloplasty on revision patellar kinematics and quadriceps tendon force: an ex vivo study

The purpose of this study was to assess the effect of 2 revision reconstructive interventions on patellofemoral joint mechanics in comparison to control. We flexed 8 cadaver knee specimens from 0 degrees to 60 degrees of flexion in a test rig designed to simulate weight-bearing flexion and extension (Oxford rig). Quadriceps tendon extensor force and patellar kinematics were recorded for control total knee arthroplasty (TKA) (normal primary TKA with patella resurfaced) and then for each of the 2 revision patellar interventions (after patelloplasty of typical revision knee patellar bone defect to leave a simple bony shell, and after TKA with augmentation patella resurfacing). Our results demonstrate that patellar kinematics and quadriceps extensor force are optimized when the patella is reconstructed to normal anteroposterior thickness.