International Knee Society Research Articles

A flat all-polyethylene tibial component in medial unicompartmental knee arthroplasty: a long-term study

The aim of this study is to present the clinical and radiological results of a cemented unicompartmental knee arthroplasty (UKA) using a flat all-polyethylene tibial component at long-term follow-up, in a homogeneous group of patients with medial femoro-tibial knee arthritis. The study group included 53 knees in 51 patients who were treated between January 1998 and November 1999 using a flat all-polyethylene tibial component. The same surgical technique was used for all patients. Inclusion criteria included a diagnosis of atraumatic arthritis, pre-operative flexion greater than 100° with no flexion deformity, a varus deformity of less than 10°, and a body mass index (BMI) less than 35. A neutral mechanical axis was considered the end-point in all interventions. The patients were assessed clinically using the International Knee Society (IKS) and the functional scores at follow-up. Plain radiographs were used to determine the alignment of the mechanical axis at 5, 10 and 14.7-year follow-up. A radiographic analysis of loosening, based on the method described by the IKS, was performed and the degree of arthritic progression in the non-resurfaced compartment was also assessed. At latest follow-up five patients had died and the data for three patients had not been collected. At final review four knees had undergone revision surgery and a further patient had declined a recommended revision TKA. The main indication for revision surgery was progressive aseptic loosening of the tibial component in female patients. No revisions were required because of arthritic progression in the lateral compartment. Over time the clinical outcomes did not show statistically significant differences. There was a significant worsening of the mechanical axis at the last follow-up compared with the results at five and ten year review. This study demonstrated that, in primary arthritis involving the medial femoro-tibial compartment, UKA using a flat all-polyethylene component could be considered an effective surgical option. Attention should be paid to progressive worsening of the mechanical axis over time associated with progressive radiolucency especially in female patients. IV.

Computer-assisted navigation for cruciate-retaining total knee arthroplasty in patients with advanced valgus arthritic knees

BackgroundThe valgus arthritic knee is a complex deformity involving both soft tissue and bony problems that significantly affect the positioning of the components for, and decrease the accuracy of, reconstructed alignment in total knee arthroplasty (TKA). The unique bony deformity and soft tissue problem makes the use of conventional mechanical instrumentation difficult and leads to unsatisfactory results. PurposeThe purpose of this study was to investigate the effect of computer-assisted navigation for TKA on the postoperative mechanical axis, component alignment, and functional outcomes in the arthritic knee with genu valgus deformity. MethodsFrom January 2003 to August 2009, 24 patients (24 knees) with advanced valgus knee arthritis who underwent computer-assisted navigation for cruciate-retaining TKA were retrospectively reviewed. The accuracy of the postoperative mechanical axis and component alignment, and functional outcomes were assessed. ResultsThe mean postoperative mechanical axis was 180.2° (range, 178.1–182.5°). All patients achieved the targeted goal of a leg axis within 3° of the neutral axis. The joint line was not substantially elevated. No patient required conversion to a constrained component to achieve stability. At a mean follow-up of 45.5 months, the Hospital for Special Surgery (HSS) knee score improved from a mean preoperative score of 55.6 to 92.8 postoperatively. The International Knee Society (IKS) clinical score improved from 42.2 to 95.9. The IKS for pain improved from 15.4 to 47.1, and the IKS knee function score improved from 35.8 to 95.4. ConclusionComputer-assisted navigation for TKA is a useful alternative technique for advanced valgus knee arthritis where accurate restoration of the joint line, proper alignment of the limb and prosthetic components, and meticulous soft tissue balancing may be challenging because of bony deformities and soft tissue contractures.

Cementless total knee arthroplasty in chronic inflammatory rheumatism

We report a short-term monocentric retrospective evaluation of cementless total knee arthroplasty (TKA) in a population suffering from chronic inflammatory rheumatism. We have reviewed 23 patients (34 knees) with an average age of 55 years (range 26-78), bearing a TKA for chronic inflammatory rheumatisms with a 6-year follow-up (range 3-12); 78% suffered from rheumatoid arthritis and 15% from juvenile rheumatoid arthritis. We used a cementless total prosthesis sacrificing the posterior cruciate ligament and bearing an ultra-congruent rotational tibial insert, the Natural Knee (NK2™) (Zimmer(®), Warsaw, IN, USA). At last follow-up, an independent surgeon performed a clinical assessment for pain, function and quality of life using International Knee Documentation Committee score, International Knee Society (IKS) score and Devane's score. A radiographic study evaluated secondary fixation according to the radiographic index of the Knee Society and according to Ewald's score. The mean postoperative IKS score was 83 points (range 40-100) for the knee score and 74 points (range 20-100) for the function score. Radiographic assessment came across only one case of loosening, concerning the tibial component on an asymptomatic patient. We came across the following complications: 1 early infection, 2 important postoperative flessum deformity having needed an arthrolysis, 1 supracondylar fracture of the femur and 1 fracture of the patellar component. Survival rate at 6-year follow-up is 97% taking into account one case of revision. Non-cementation of this implant in chronic inflammatory rheumatism does not result in a higher rate of loosening. In this series, patients own satisfaction, function of the knee and survival rate are rather good. Retrospective, no control group, Level IV.

Medial unicompartmental knee arthroplasty: Does tibial component position influence clinical outcomes and arthroplasty survival?

In several recent studies, unicompartmental knee arthroplasty (UKA) produced better functional outcomes than did total knee arthroplasty with 10-year prosthesis survival rates greater than 95%. Nevertheless, UKA is still widely viewed as producing inconsistent results. Tibial component loosening is the leading cause of failure. We consequently sought to identify tibial component position criteria associated with outcomes of medial UKA. We conducted a retrospective multicentre study of 559 medial UKAs performed between 1988 and 2010 in 421 patients (262 females and 159 males) with a mean age of 69.51±8.72 years at surgery. We recorded the following radiographic parameters: joint space height, obliquity and slope of the tibial implant, whether the tibial component was perpendicular to the femoral component, and lower limb malalignment. The International Knee Society (IKS) score was used to assess clinical outcomes. Mean follow-up at re-evaluation was 5.17±4.33 years. The mean 10-year prosthesis survival rate was 83.7±3.5%. Factors associated with decreased prosthesis survival were a greater than 2-mm change in joint space height, a greater than 3° change in tibial component obliquity, a slope value greater than 5° or a change in slope greater than 2°, and more than 6° of divergence between the tibial and femoral components. Residual mechanical varus of 5° or more was also associated with mechanical failure. The only factor associated with worse functional score values was joint space elevation by more than 2mm. The high level of accuracy required for optimal positioning of the tibial component during medial UKA indicates a need for considerable technical expertise and emphasises the conservative nature of the procedure. Optimal positioning is crucial to restore normal knee kinematics and to prevent implant wear and lesions to adjacent compartments. IV, retrospective study.

Poor short-term outcomes after computer-assisted rotating-platform total knee arthroplasty with a deep-trochlear-groove femoral component: Analysis of 19 patients

Congruent rotating tibial plateaus are designed to minimise wear after total knee arthroplasty (TKA). The Score™ prosthesis has a congruent rotating tibial plateau, a deep trochlear groove, and uses a computer-assisted navigation system for ligament balancing. Although this prosthesis is widely utilized, no accurate data on outcomes are available. The innovative features of the Score™ prosthesis, most notably patellar replacement with a highly constrained femoral component, do not jeopardize implant survival. In a pilot study, we retrospectively evaluated outcomes of 19 patients treated with Score™ knee replacement between February and October 2006 (mean age, 66.8 years; range, 58-82 years). The evaluation criteria were the International Knee Society (IKS) scores and prosthesis survival rate estimated using Kaplan-Meier plots with failure defined as revision need to change the prosthesis. Mean follow-up was 35.3 months. The IKS knee score increased from 27.4 (5-60) preoperatively to 81.4 (45-99) at last follow-up (P<0.0001). Mean mechanical axis was 181.2° (180-186°), with 16 between 180° and 183°. Revision surgery was required in five cases (for patellar complications with combined motion-range limitation in flexion (<90°) and extension (5-20°) in three cases, isolated motion-range limitation in one case, and recurvatum deformity with instability in one case). Prosthesis survival was 82% (73-91%) after 24 months and 65% (51-78%) after 44 months. The deep trochlear groove femoral component resulted in patellar complications, which were the most common reasons for revision surgery, together with motion-range limitation and instability possibly related to improper use of the navigation system. This small retrospective case-series study showed an unusually low prosthesis survival rate probably related to the implant design. We no longer use the Score™ prosthesis, despite the availability of a dedicated navigation system, and we recommend careful monitoring of patients who have this prosthesis. Level IV, retrospective study.

Simultaneous Unicompartmental Knee Arthroplasty and Lateral Patellar Facetectomy for Bicompartmental Degenerative Disease

ABSTRACT Introduction Unicompartmental knee arthroplasty (UKA) is a treatment option in patients with unicompartmental degenerative disease. Compared to total knee arthroplasty (TKA), the advantages of UKA include accelerated recovery and cruciate ligament retention. These advantages, along with emerging evidence that mild patellofemoral joint osteoarthritis does not compromise results of UKA have encouraged expansion of the indications for UKA. Symptomatic lateral patellofemoral joint degenerative disease is a common cause of UKA revision. Partial lateral patellar facetectomy can provide relief from symptoms of lateral patellofemoral degenerative disease. We hypothesize that simultaneous UKA and lateral patellar facetectomy provides durable pain relief and functional improvement in a patient population with degenerative disease of one tibiofemoral compartment and the lateral patellofemoral joint. Materials and methods: Between 2004 and 2008, 11 lateral UKA's were performed in association with partial lateral patellar facetectomy in 11 female patients (mean age: 66.7 years) with degenerative changes in one tibiofemoral compartment and the lateral patellofemoral joint. Patients were followed clinically and radiographically for a mean of 5 years. Results No patient underwent revision surgery in the followup period. The mean international Knee Society (IKS) knee score improved from 64.9 ± 11.2 points preoperatively to 87.5 ± 12.6 points at final follow-up (p = 0.01). The mean IKS functional score improved from 65.9 ± 23.5 points preoperatively to 83.2 ± 23.3 points at final follow-up (p = 0.012). The mean Kujala score was 84.3 ± 13.5 points postoperatively. Progression of patellofemoral OA was observed in one patient. Conclusion Simultaneous UKA and partial lateral patellar facetectomy is a viable treatment option for symptomatic degenerative disease involving one tibiofemoral compartment and the lateral patellofemoral joint. This treatment approach may be a useful alternative to TKA or bicompartmental arthroplasty in a carefully selected patient population. Level of evidence Case series—Level IV. Magnussen RA, Gancel E, Servien E, Jacobi M, Demey G, Neyret P, Lustig S. Simultaneous Unicompartmental Knee Arthroplasty and Lateral Patellar Facetectomy for Bicompartmental Degenerative Disease. The Duke Orthop J 2013;3(1):61-66.

Bilateral total knee arthroplasty in a one-stage surgical procedure

Bilateral total knee arthroplasty (TKA) in a one-stage surgical procedure has the advantage of a single hospital stay, shorter rehabilitation, and reduced patient management costs. However, until now the use of this strategy has been limited by the fear of a higher rate of perioperative complications. The hypothesis of this study was that in selected patients, this management strategy would not result in any serious complications. This prospective 24-month pilot study was performed in a continuous series of patients without a control group. Inclusion criteria were bilateral non-infectious gonarthropathy, in patients classified as American Society of Anesthesiology (ASA)1 or2 and presenting with a preoperative hemoglobin level of at least 13g/dL. All patients underwent a pre- and postoperative evaluation using the International Knee Society (IKS) and Knee Injury and Osteoarthritis Score (KOOS) scores. Thirty patients were included in the study (25women, mean age 70.3years old [32 to 88years]; five ASA1 and 25 ASA2). All patients were followed-up and evaluated for a mean 18months (6 to 30months). Three deep vein thromboses, one cardiopulmonary accident and three confusional states were reported, but there were no perioperative deaths, pulmonary embolisms, nosocomial infections or revision procedures. At 18months follow-up the IKS score had improved from 98 (33-139) preoperatively to 169 (62-200) postoperatively. The five items of the KOOS score improved significantly. This preliminary series confirms that bilateral total knee replacement in a one-stage surgical procedure is a reliable alternative to a two-stage procedure in ASA1 and2 patients. Because of the savings in health costs with this strategy, public healthcare authorities should provide support by creating and sponsoring a specific group for further study. 4, prospective, no control group.

The effect of tibio-femoral over-distraction in primary knee arthroplasty

Overstuffing the patellofemoral joint has been associated with poor post-operative outcomes. No study has assessed the effect of over-distracting the tibio-femoral joint in the vertical plane and its effects on function and quality of life. The purpose of this study is to assess the effect of tibio-femoral joint distraction on function and quality of life after total knee arthroplasty. Measurements of knee joint distraction were devised using long-leg alignment radiographs. Seventy-three patients were prospectively recruited and their joint distraction measured post-operatively. A comparison was made between the level of joint distraction and functional outcomes as measured by the International Knee Society score and its components, such as pain and flexion, and the Knee injury and Osteoarthritis Outcome Score and quality of life as measured by the Short-Form 12 score. Twelve-month follow-up was achieved. Knee joint over-distraction post-arthroplasty correlated significantly with Knee Society score (p = 0.041), flexion (p = 0.005) and pain (p = 0.002). Those knees that were over-distracted post-operatively suffered more pain, less flexion and a lower International Knee Society score compared with their counterparts. No correlation was found between over-distracting the knee joint and quality of life. Over-distracting the tibio-femoral joint during arthroplasty is a significant predictor of reduction in function and increase in pain in the short to medium term. When between sizes of tibial inserts, the surgeon should consider using the thinner option.

Coronal Alignment Correlates With Outcome After Total Knee Arthroplasty: Five-Year Follow-Up of a Randomized Controlled Trial

In a prospective randomized control trial comparing computer-assisted vs conventional total knee arthroplasty, we previously reported that patients with coronal alignment within 3° of neutral had superior international knee society and Short-Form 12 (SF-12) physical scores at 6 weeks, 3 months, 6 months, and 12 months after surgery. Computer-assisted total knee arthroplasty achieved greater accuracy in implant alignment, and this correlated with better knee function and quality of life. At 5 years, 90 of 111 patients assessed in our original study were reviewed. Coronal alignment within 3° of neutral continued to be correlated with superior International Knee Society and SF-12 scores. Coronal alignment greater than 3° was associated with a significant decline in SF-12 mental health scores.

TKA outcomes after prior bone and soft tissue knee surgery

Bone surgery around the knee joint could represent a more traumatic prior surgical procedure compared to soft tissue knee surgery and may predispose to differing postoperative total knee arthroplasty (TKA) outcomes. The objective of this study was to analyse the postoperative results as well as complications and failures in two groups of patients that had undergone knee surgery prior to primary TKA (bone surgery and soft tissue surgery) when compared to the no prior surgery group. A retrospective and cohort series of 1,474 primary TKA were evaluated at minimum follow-up period of 2 years: 1,119 primary TKA underwent no prior surgery (1,119 patients) (group A), 85 primary TKA (85 patients) (group B) had prior bone procedure [high tibial osteotomy (n = 64), tibial plateau fracture (n = 10) and patellar realignment (n = 11)], and third group of 146 primary TKA (146 patients) (group C) had undergone a soft tissue procedure [arthroscopy (n = 60) and menisectomy (n = 86)] before primary TKA. All the patients underwent a clinical and radiological evaluation as well as International Knee Society (IKS) scores. Preoperatively, group B had 40 % of cases classified as stage IV knee arthritis (p < 0.02); while 57 % of cases in group A showed higher levels of knee malalignment (p = 0.001) and group C had lower BMI (p = 0.001). Intraoperative complications revealed no difference. Although group B had the poorest postoperative mean values of knee flexion, TKA procedure improved the preoperative mean values of knee flexion in all the study groups. The postoperative complications were more prevalent in group C (p < 0.001), while the percentage of revision TKA was similar for all study groups (p = 0.5). At 120-month follow-up, the Kaplan-Meier survival curve rates showed no difference (p = 0.29). This study confirms that prior knee surgery could be considered a clinical condition predisposed to higher postoperative complication rate in primary TKA compared to the no prior surgery group. After analysing the three study groups, group C showed a higher rate of postoperative local complications and lower IKS knee scores, while the group B showed the poorest postoperative mean values of knee flexion as well as the need for extended surgical approach (TTO approach) was more prevalent in this study group. However, statistical analysis did not reveal a direct correlation between the type of prior knee surgery and TKA failures.

Revision of Minimal Resection Resurfacing Unicondylar Knee Arthroplasty to Total Knee Arthroplasty: Results Compared With Primary Total Knee Arthroplasty

We compared a cohort of patients undergoing revision of a minimal resection resurfacing unicompartmental knee arthroplasty (UKA) to total knee arthroplasty (TKA) with a cohort of patients undergoing primary TKA. Both cohorts were matched in terms of age, sex, and body mass index. We collected data on preoperative and postoperative range of motion, International Knee Society scores, and radiologic data. We also collected data on the modes of failure of the primary UKA. There were 55 patients in each cohort. The average time the UKA was in place was 48.3 months. The average follow-up period from the time of revision was 39.2 months. The most common reason for revision was subsidence of the tibial base plate (58%). Forty percent of patients required particulate bone grafting for contained defects. Two patients required metal augments, and 1 required stems. There was no significant difference between the 2 groups in terms of range of motion, functional outcome, or radiologic outcomes. Revision of these types of implants to TKA is associated with similar results to primary TKA and is superior to revision of other forms of UKA.

Associations between pre-operative radiographic changes and outcomes after total knee joint replacement for osteoarthritis

To assess the influence of pre-operative X-ray changes on the response to total knee joint replacement (TKR). We included patients from one centre who underwent primary TKR (n = 478) for osteoarthritis in 2006 and 2007. The International Knee Society score (IKSS) and short form health survey were collected pre-operatively and at 1 and 2 years after surgery. Pre-operative radiographs were read to assess Kellgren and Lawrence (K-L) grading, individual radiographic features using the OARSI atlas, and subchondral bone attrition using the Ahlbach method. The main independent variable was a modified (K-L) grade. The outcome variables were the IKSS pain and function scores. Covariates included demographic features, co-morbidities, baseline pain and function, prosthesis type, and the use of patella resurfacing. Multivariable linear regression models were created to assess the relationships between pre-operative X-ray findings and pain and function outcomes. On average, pain and function improved greatly following surgery. However, pain relief was unsatisfactory in about 30%, and functional improvement suboptimal in about 50%. OR (95% CI) for ongoing moderate-severe pain at 12 months for modified K-L grades; <3: 5.39 (1.23-15.69), 3a: 2.62 (1.21-5.67), 3b: 1.81 (1.00-3.26), 4a: 2.06 (1.05-4.05) when compared to 4b. OR (95% CI) for poor function at 12 months were; 3a: 2.81 (1.23-6.39) and 4a: 2.45 (1.22-4.91), when compared to 4b. Patients with more severe radiographic knee damage at the time of surgery are most likely to have substantial gains in terms of both pain relief and improved function as a result of a TKR.

Mid- to long-term results of revision total knee replacement using press-fit intramedullary stems with cemented femoral and tibial components

This was a retrospective analysis of the medium- to long-term results of 46 TC3 Sigma revision total knee replacements using long uncemented stems in press-fit mode. Clinical and radiological analysis took place pre-operatively, at two years post-operatively, and at a mean follow-up of 8.5 years (4 to 12). The mean pre-operative International Knee Society (IKS) clinical score was 42 points (0 to 74), improving to 83.7 (52 to 100) by the final follow-up. The mean IKS score for function improved from 34.3 points (0 to 80) to 64.2 (15 to 100) at the final follow-up. At the final follow-up 30 knees (65.2%) had an excellent result, seven (15.2%) a good result, one (2.2%) a medium and eight (17.4%) a poor result. There were two failures, one with anteroposterior instability and one with aseptic loosening. The TC3 revision knee system, when used with press-fit for long intramedullary stems and cemented femoral and tibial components, in both septic and aseptic revisions, results in a satisfactory clinical and radiological outcome, and has a good medium- to long-term survival rate.

Associations between pre-operative radiographic changes and outcomes after total knee joint replacement for osteoarthritis

Purpose: Knee joint replacement (KJR) for OA is a successful intervention, but about 20% of KJR patients obtain little or no improvement. The reasons for this are unclear. The purpose of this study was to investigate whether pre-operative radiographic changes predict pain and functional outcomes. Methods: Data from a prospective single-centre cohort study of patients undergoing TJR between Jan 1st 2006 and Dec 31st 2007 were analysed (n = 525). Pre-operative data collection included demographics (age, sex, BMI, self-reported co-morbidities), the International Knee Society Score (IKSS), and the Short Form Health Survey (SF-12). Pre-operative (within 6 months of surgery) AP standing and lateral radiographs were read by a single observer using the Kellgren and Laurence (K&L) and Altman atlases, and the scoring repeated on a random 10% sample to assess rater reliability. Post-operative data collection at 12 and 24 months included the IKSS and SF-12. Linear and logistic regression analyses were undertaken to assess the relationships between baseline radiographic features and pre and post-operative pain and function. Results: Of the 525 cases 24 were excluded as they had undergone uni-compartmental replacements, and 23 radiographs were rejected, leaving 478 TJR cases for inclusion. 5 and 24 were unable to complete the 12 or 24 month data respectively due to death, loss to follow-up or refusal. The amount of missing data was well below 5%. The mean age of the subjects was 70.8 years (+/- 8.3), 69% were female and the mean BMI was 32.2. Pain scores improved from a mean of 4.0(+/-7.3) to 34.9 at 12 months and 34.8 (+/- 15.9) at 24 months; however about 30% of patients still complained of moderate or severe pain in the operated knee at each time point. Function scores improved from a mean of 37.5 (+/- 18.1) pre-operatively to 58.8 and 55.5 (+/- 26.8) at one and two years respectively. Inter-rater reliability scores for radiographic features were satisfactory, ranging from a kappa of 0.80 (lateral joint space narrowing) to 0.65 (lateral osteophyte score). The majority had OA K&L grade 3 (57 with mild (3a) and 200 with severe (3b) JSN) or 4 (87 without (4a) and 119 with (4b) bone attrition). The commonest compartmental distributions were medial and patella-femoral (244), or medial only (104). There were no significant associations between pre-operative radiographic scores and pre-operative pain or function, but radiographic severity was associated with outcome. Those with lower K&L grades and less compartmental involvement were less likely to have obtained improvements in pain at either 12 or 24 months (e.g. the odds ratio for ongoing pain in the operated joint at 12 months comparing those with K&L grades <3 to those with grade 4b was 5.23 (CI 1.5 to 17.6), p=0.008). The relationships between pre-operative radiographs and function were similar but less strong. Outcome did not appear to differ for those with predominant medial, lateral or patella-femoral joint involvement. Multivariate analyses showed that other significant, independent determinants of improvement in pain and function included age, mental function score of the SF-12 and pre-operative pain and function (both pain and function), as well as gender and BMI (function only). Conclusions: The data suggest that we should exercise caution when considering surgery for patients with severe pain but mild radiographic changes, and conversely, that those with severe joint damage, irrespective of which compartments are involved, are more likely to respond well to surgery. A possible explanation for this is that in those with severe pain and mild joint damage the pain is driven more by central sensitisation than by any nociceptive input from the joint.

The association between radiographic severity and pre-operative function in patients undergoing primary knee replacement for osteoarthritis

ObjectiveTo determine the association between radiographic osteoarthritis (OA) and pre-operative function in patients undergoing primary knee replacement. MethodsSingle centre study examining pre-operative outcomes in a consecutive series of 525 patients who underwent primary knee replacement for OA between January 2006 and December 2007. Pre-operative data included: demographics, American Society of Anaesthesiologists (ASA) status and OA in the contralateral knee. The International Knee Society (IKS) rating and Short Form-12 (SF-12) were recorded for each patient. Pre-operative radiographs were read by a single observer for Kellgren and Lawrence (K&L) grading and Osteoarthritis Research Society International (OARSI) atlas features. Multiple linear regression was used to assess the strength of associations between radiographic OA severity and function, adjusting for clinically relevant variables. ResultsLateral tibiofemoral osteophyte grade was an independent predictor of pre-operative function as determined by the functional sub-scale of the IKS in patients undergoing primary knee replacement (coefficient=2.58, p=0.033). No associations were evident between pre-operative function and modified K&L, joint space narrowing, Ahlbäck attrition and coronal plane deformity. Other statistically significant predictors of poorer pre-operative function included: advancing age, female gender, knee pain and poorer SF-12 mental component summary scores which including osteophyte grade accounted for 24.6% of the variation in functional scores, (r=0.496). ConclusionOsteophytes in the lateral compartment of the knee were associated with pre-operative function in patients with advanced knee OA. Further studies are required which examine individual radiographic features specifically in patients with advanced knee OA to determine their relationship to pre-operative pain and function.

Influence of gender on the outcome of total knee arthroplasty

Total knee arthroplasty (TKA) is a common treatment for osteoarthritis. Recently, there has been interest in the anatomical differences between male and female knees and possible effects on outcome. The purpose of this study is to analyze whether gender influenced on clinical outcome, radiographic findings, revision rate, or complications of TKAs performed with unisex components. Six hundred eighty-one patients (28% male and 72% female) treated with TKA were evaluated. Similar patient age, body mass index, International Knee Society (IKS) knee score, range of motion, and stage of osteoarthritis were noted in both groups pre-operative. IKS function score and activity level were higher in the male group. At a mean of 2.3 years post-operative, both groups demonstrated similar increases in IKS scores. Function scores and activity levels remained higher in the male group. No differences in radiologic findings or revision rates were noted. Slightly higher infection rates were noted in the male group.

Muscle activity around the knee and gait performance in unicompartmental knee arthroplasty patients: a comparative study on fixed- and mobile-bearing designs

Unicompartmental knee arthroplasty (UKA) offers clinical and functional advantages over total knee arthroplasty. The aim of this study was to compare the functional recovery of patients with mobile UKA versus fixed-bearing designs by state-of-the-art gait analysis and, in particular, by assessing muscular activity. Ten patients with the Oxford (mobile bearing) and ten patients with Optetrak (fixed bearing) UKA were evaluated at a minimum follow-up of 1 year post-operatively by gait analysis, which includes the main time-distance parameters, kinematics and kinetics of the replaced knee, and muscular activity of the main relevant muscles. Twenty healthy young subjects were used as controls. The mean International Knee Society score was 92.7 ± 11.2 for all 20 UKA knees; for the Oxford UKA, it was 94.1 ± 9.5; and for the Optetrak UKA, it was 91.5 ± 12.9, although follow-up was significantly lower for the latter. Time-distance parameters showed a slower gait in both groups compared with that of controls, and the Oxford group had values closer to the controls. Knee joint flexion was similar to that of controls at initial contact and loading response with no differences between groups. In all patients, the joint moments were smaller to that of controls. Residual abnormalities such as the prolonged rectus femoris activity were present in both designs, and the only difference distinguishing the Optetrak group from the others was the combined co-contraction of the hamstrings. A good restoration of gait was achieved by most unicompartmental knee patients independently of the UKA design, although some abnormalities persisted in muscle activity around the knee. Retrospective comparative study, Level III.

Residual Varus Alignment does not Compromise Results of TKAs in Patients with Preoperative Varus

Postoperative varus alignment has been associated with lower IKS scores and increased failure rates. Appropriate positioning of TKA components therefore is a key concern of surgeons. However, obtaining neutral alignment can be challenging in patients with substantial preoperative varus deformity and it is unclear whether residual deformity influences revision rates. We asked: (1) in patients with preoperative varus deformities, does residual postoperative varus limb alignment lead to increased revision rates or lower IKS scores compared with correction to neutral alignment, (2) does placing the tibial component in varus alignment lead to increased revision rates and lower IKS scores, (3) does femoral component alignment affect revision rates and IKS scores, and (4) do these findings change in patients with at least 10° varus alignment preoperatively? From a prospective database, we identified 553 patients undergoing TKAs for varus osteoarthritis. Patients were divided into those with residual postoperative varus and those with neutral postoperative alignment. Revision rates and International Knee Society (IKS) scores were compared between the two groups and assessed based on postoperative component alignment. Survival analysis was conducted with revision as the endpoint. The analysis was repeated in a subgroup of patients with at least 10° preoperative varus. Minimum followup was 2 years (median, 4.7 years; range, 2-19.8 years). The two groups had similar survival rates to 10 years and similar IKS scores. Varus tibial component alignment and valgus femoral component alignment were associated with lower mean scores. Revision rates and scores were similar in a subgroup of patients with substantial preoperative varus. Our data suggest residual postoperative varus deformity after TKA does not increase survival rates at medium-term in patients with preoperative varus deformities, providing tibial component varus is avoided. Tibial component varus negatively influences IKS score. Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Unicompartmental knee replacement provides early clinical and functional improvement stabilizing over time

Unicompartmental knee replacement preserves uninvolved osteocartilaginous and soft tissue structures, thereby allowing a more physiological and early clinical and functional recovery. The aim of this study was to report the results of ZUK unicompartmental fixed metal-back prosthesis and how these results change over time. Between 2005 and 2007, 80 ZUK prostheses were implanted in 80 patients for unicompartmental osteoarthritis or osteonecrosis. Patients were clinically assessed using the International Knee Society scores. Postoperative values of mechanical axis were calculated 12 months after surgery and compared to the preoperative ones. The mean International Knee Society knee and function scores improved, respectively, from 46 ± 9 and 54 ± 8 preoperatively to 82 ± 5 and 94 ± 3 at the last follow-up (P < 0.001). Average flexion increased from 110° ± 9° to 127° ± 8° (P < 0.01). Patients with unicompartmental knee reached good clinical outcome very early and remained at the same level. Age did not significantly influence clinical and functional scores. High success rates of the modern unicompartmental knee implants depend on the materials and design evolution, improvement of the surgical technique, and the strong restriction of indications. Prospective non-randomized case-series study, Level IV.

The EUROP total knee prosthesis: A ten-year follow-up study of a posterior cruciate-retaining design

The success of total knee arthroplasty is measured by pain relief, functional recovery, and implant survival duration. The aim of the present study was to evaluate the long-term clinical, functional and radiological results of the posterior cruciate ligament (PCL)-retaining fixed bearing EUROP implant. The long-term results of EUROP implants are similar to those reported with comparable prostheses. We performed a prospective, monocentric study of a series of 121 cemented EUROP total knee arthroplasties, implanted between 1994 and 1996 in 117 patients mean age 73. A clinical and radiological evaluation was performed at 10 years of follow-up according to the International Knee Society (IKS) score. Twenty-three patients died, 14 were lost to follow-up, 43 underwent clinical and radiological evaluation and 37 were questioned by telephone. The preoperative IKS knee score was 31 points (0-60) and increased to 88 points (30-98) at final follow-up, IKS function increased from 40 (0-90) to 80 points (25-100). Radiolucencies were observed in 56% of the condyles and 60% of tibial plates. Ninety-three percent of these radiolucent lines were less than 1mm wide. Three patients underwent revision TKA at 32 months, eight and 11 years respectively. Global implant survival was 99% at five years, 97.8% at 10 years and 95.8% at 12 years. The clinical and radiological results of the cruciate-retaining fixed bearing EUROP total knee arthroplasties, with three cases of revision arthroplasty at 12 years of follow-up are satisfactory and comparable to similar implants.