Improved Range of Motion and Patient-Reported Outcome Scores With Fixed-Bearing Revision Total Knee Arthroplasty for Suboptimal Axial Implant Rotation

BackgroundSuboptimal implant rotation has consequences with respect to knee kinematics and clinical outcomes. We evaluated the functional outcomes of revision total knee arthroplasty (TKA) for poor axial implant rotation.MethodsWe retrospectively reviewed 42 TKAs undergoing aseptic revision for poor axial implant rotation. We assessed improvements in Knee Society Score (KSS) and final range of motion (ROM). Subgroup analyses were performed for preoperative instability and stiffness, as well as the number of components revised and level of implant constraint used.ResultsRevision for poor axial rotation in isolation improved KSS from 52 ± 22 to 84 ± 25 (P < .001), and flexion increased from 105 ± 21° to 115 ± 13° (P = .001). Revision in the setting of instability significantly improved the KSS (P < .001) but did not affect ROM (P = .172). Revision in the setting of stiffness significantly improved both KSS (P < .001) and ROM (P = .002). There was no statistically significant difference between the postoperative KSS (P = .889) and final knee flexion (P = .629) with single- or both-component revision TKA for isolated poor axial rotation or between the postoperative KSS (P = .956) and final knee flexion (P = .541) with or without the use of higher constraint during revision TKA for isolated poor axial rotation.ConclusionRevision TKA for poor axial alignment improves clinical outcomes scores and functional ROM.     

Comparison of Cruciate-Sacrificing vs Posterior-Stabilized Total Knee Replacement Using a Contemporary Total Knee System

BackgroundThe use of highly conforming polyethylene tibial inserts in cruciate-retaining total knee arthroplasty (TKA) often requires posterior cruciate ligament (PCL) release/sacrifice for balancing (CS TKA). The CS TKA relies on the posterior capsule, collateral ligaments, and articular conformity without a cam or post to achieve stability. Using prospectively collected data we compared clinical outcomes of CS TKA to posterior-stabilized (PS) TKA utilizing a contemporary TKA system.MethodsSixty-nine consecutive CS TKAs were compared to 45 consecutive PS TKAs at 2-year minimum follow-up. CS knees were balanced with the PCL released. Preoperative/postoperative range of motion (ROM), Knee Society Scores (KSS), stair function, and squatting ROM were analyzed.ResultsAt minimum 2-year follow up, CS and PS TKA demonstrated significant improvement in ROM (P < .001), KSS (Pain, P < .001; Function, P < .001), and KSS stair function (P < .001), with no revisions. There was no difference in preoperative to postoperative improvements for passive knee ROM (10° (0°-20°) vs 13° (5°-25°); P = .16), KSS Pain (34 (21-42) vs 38 (24-46); P = .22), KSS Function (35 (30-50) vs 35 (18-50); P = .34), and KSS stair function (10 (10-20) vs 10 (0-20); P = .37) for CS and PS TKA, respectively. CS TKA had higher squatting ROM (P = .02) at minimum 2-year follow-up compared to PS TKA.ConclusionBoth PS and CS TKA provided significant improvement in clinical outcomes, with no differences in passive ROM, KSS, or stair function postoperatively. Our data support that with proper articular conformity and balancing, cruciate-retaining TKA in a PCL-deficient knee (CS TKA) is appropriate. This may be design specific and further prospective randomized studies are needed to corroborate these findings.     

Comparison of the clinical and radiological outcomes between an isolated tibial component revision and total revision knee arthroplasty in aseptic loosening of an isolated tibial component

BackgroundAn isolated tibial component revision could be a treatment option for isolated tibial side loosening; however, few studies have proved its efficacy. This study aimed to compare the clinical and radiological outcomes between isolated (tibial component) and total (femoral and tibial component) revision total knee arthroplasty (TKA).MethodsBetween January 2008 and February 2017, 31 patients underwent revision TKA for isolated tibial side loosening; 14 underwent an isolated tibial component revision (isolated group) and 17 underwent total (both femoral and tibial components) revision surgery (total group). The postoperative range of motion (ROM), Western Ontario and McMaster Universities osteoarthritis (WOMAC) index, Knee Society knee score (KSKS), Knee Society function score (KSFS), and mechanical axis (MA) were compared between the two groups. The intraoperative tourniquet time and amount of blood drainage were also compared.ResultsThe mean follow-up durations in the isolated and total groups were 40.7 and 56.1 months, respectively. Both groups had similar postoperative ROM, WOMAC index, KSKS, KSFS, and MA; however, significantly shorter tourniquet time (105.2 vs. 154.6 min, P < 0.001) and less blood drainage (417.2 vs. 968.1 ml, P < 0.001) were noted in the isolated group than in the total group.ConclusionIsolated tibial component revision TKA for tibial component loosening showed comparable clinical and radiological outcomes to those of total revision TKA. The advantages of the isolated tibial component revision surgery were short operation time and small blood loss.Study designLevel III, Retrospective comparative study.     

Total Knee Arthroplasty After Intramedullary Tibial Nail: A Matched Cohort Study

BackgroundAs the use of intramedullary nails (IMNs) has become more common, there are an increasing number of patients requiring total knee arthroplasty (TKA) who have an indwelling tibial IMN. The purpose of this study is to compare implant survivorship, clinical outcomes, and complications in patients undergoing primary TKA with a history of tibial IMN to those without.MethodsWe retrospectively identified 24 TKAs performed between 2000 and 2017 after ipsilateral tibial IMN. Patients were matched 1:2 to patients undergoing primary TKA without history of tibial IMN based upon age, gender, body mass index, and year of surgery. Mean follow-up was 7 years.ResultsThe 10-year survivorship free of any revision was 100% for the tibial IMN cohort, and 96% for the control cohort, while the 10-year survivorship free of any reoperation was 91% and 89%, respectively (P = .72). Patients with a history of tibial IMN had similar Knee Society Scores to matched controls at 2 years (P = .77) and 5 years (P = .09). Acquired idiopathic stiffness trended toward being more common (17% vs 6%, P = .21) and operative time trended toward being longer (135 vs 118 min, P = .07) when the tibial IMN was removed, but there was no overall difference in complication rate between cohorts.ConclusionsTo our knowledge, this is the first report of primary TKA in patients with a history of ipsilateral tibial IMN. Compared to a matched cohort of patients without tibial IMN, these patients have similar outcomes in regards to implant survivorship, clinical outcomes, and risk of complications.Level of EvidenceTherapeutic Level III.     

Isolated Polyethylene Insert Exchange for Flexion Instability After Primary Total Knee Arthroplasty Demonstrated Excellent Results in Properly Selected Patients

BackgroundHistorically, isolated polyethylene exchange (IPE) for flexion instability after total knee arthroplasty (TKA) has demonstrated generally poor and unpredictable results. The purpose of this study is to evaluate the results of a single surgeon’s strict indications and protocol for IPE for flexion instability after primary TKA.MethodsBetween 2009 and 2016, 418 revision TKAs were performed by the senior author. Patients were considered for IPE if they demonstrated excellent radiographic alignment and component positioning preoperatively. Intraoperatively, if component rotation, sizing, and fixation were all excellent and the flexion and extension gaps could be balanced, then IPE was performed.We retrospectively reviewed 31 knees in 30 patients who were treated with IPE specifically for flexion instability after primary TKA. The mean follow-up was 41 months (range, 24-85 months). Nineteen knees were cruciate-retaining TKAs revised to a more constrained “deep-dish” ultracongruent insert, and 12 posterior-stabilized TKAs were revised to thicker posterior-stabilized insert.ResultsAt a mean follow-up of 41 months, only 2 of 31 knees (6.5%) required subsequent component revision surgery for recurrent instability. Knee Society pain scores improved from 70 preoperatively to 86 postoperatively (P < .0001), and function scores improved from 39 points preoperatively to 44 points postoperatively (P = .015).ConclusionIPE for flexion instability in carefully selected patients was successful in over 90% of patients for a mean follow-up of 41 months. Pain and function scores significantly improved. Longer-term follow-up is necessary to determine whether these results are durable over time.     

Comparison of Anterior-Stabilized and Posterior-Stabilized Total Knee Arthroplasty in the Same Patients: A Prospective Randomized Study

BackgroundA highly conforming, anterior-stabilized (AS) insert is designed to provide anteroposterior (AP) stability of the posterior-stabilized (PS) insert without a post. The purpose of this study was to compare the static and dynamic stability and function of AS and PS total knee arthroplasty (TKA) in the same patients.MethodsA prospective, randomized controlled trial was performed in 45 patients scheduled to undergo same-day bilateral TKA. One knee was randomly assigned to receive an AS TKA, and the other knee was scheduled for a PS TKA from the same knee system. At 2 years postoperatively, the static AP stability was compared using anterior and posterior drawer stress radiographs at 90° knee flexion. Dynamic AP stability was evaluated using one-leg standing lateral fluoroscopic images throughout the range of motion. Knee function was compared using the Knee Society Score and Western Ontario and McMaster Universities Osteoarthritis Index score.ResultsAt 2 years postoperatively, there was a significant difference in knee AP laxity at 90° of flexion between the two groups (7.6 ± 3.9 mm in the AS group vs 2.2 ± 2.3 in the PS group, P < .001). However, there were no differences in dynamic AP stability under one-leg standing fluoroscopic lateral images at 30°, 60°, and 90° knee flexion (P = .732, P = .764, and P = .679, respectively). The Knee Society Score and Western Ontario and McMaster Universities Osteoarthritis Index scores were not significantly different between the two groups (P = .641 and P = .582, respectively).ConclusionDespite the fact that the AS TKA group showed significantly more static posterior displacement than the PS TKA group at 90° of knee flexion, both the AS and PS TKA groups showed similar dynamic stability under weight-bearing conditions and knee function at 2 years postoperatively.     

The Effect of Polyethylene Liner Thickness on Patient Outcomes and Failure After Primary Total Knee Arthroplasty

BackgroundThe effect of using thicker liners in primary total knee arthroplasty (TKA) on functional outcomes and aseptic failure rates remains largely unknown. As such, we devised a multicenter study to assess both the clinical outcomes and survivorship of thick vs thin liners after primary TKA.MethodsA search of our institutional databases was performed for patients having undergone bilateral (simultaneous or staged) primary TKA with similar preoperative and surgical characteristics between both sides. Two cohorts were created: thick liners and thin liners. Outcomes collected were as follows: change in Knee Society Score (ΔKSS), change in range of motion, and aseptic revision. Ad hoc power analysis was performed for ΔKSS (⍺ = 0.05; power = 80%). Differences between cohorts were assessed.ResultsAbout 195 TKAs were identified for each cohort. ΔKSS and change in range of motion in the thin vs thick cohorts were similar: 51.4 vs 51.6 (P = .86) and 11.1° vs 10.0° (P = .66), respectively. No difference in aseptic revision rates were observed between thin and thick cohorts: all cause (4.1%, 3.1%; P = .59), aseptic loosening (0.5%, 0.5%; P = 1.0), instability (0.5%, 0.5%; P = 1.0), all-cause revision for stiffness (3.1%, 2.1%; P = .52), manipulation under anesthesia (2.1%, 2.1%; P = 1.0), and liner exchange (0.5%, 0%; P = .32).ConclusionThe results of this study suggest that both rates of revision surgery and clinical outcomes are similar for TKAs performed with thick and thin liners. Preoperative factors are likely to play an important role in liner thickness selection, and emphasis should be placed on ensuring sound surgical technique.     

Sagittal Alignment of the Femoral Component and Patient Height Are Associated With Persisting Flexion Contracture After Primary Total Knee Arthroplasty

BackgroundThe aim of our retrospective case-control study is to identify risk factors associated with a persisting flexion contracture after total knee arthroplasty (TKA). This is an important clinical issue as a flexion contraction can lead to poor long-term clinical outcomes and patient satisfaction after TKA.MethodsThe study group included 120 knees treated for a varus osteoarthritic deformity of the knee using a posterior cruciate-retaining TKA. We evaluated the association between a flexion contracture >10°, 2 years after surgery, and the following potential risk factors, using logistic regression analysis: age, body height, body mass index, preoperative knee extension and hip-knee-ankle angle, and radiological parameters of component alignment, namely the femoral component medial angle, the femoral component flexion angle (FFA), the tibial component medial angle, and the posterior tibial slope.ResultsOf the 120 knees, a persisting flexion contracture >10° was identified in 33 (28%). The mean FFA in these cases was 7.3° (standard deviation, 1.4) compared to 4.2° (standard deviation, 1.2) for cases with a contracture of ≤10° (P = .034). On multivariate analysis, the FFA (odds ratio, 3.73; 95% confidence interval, 1.16-17.81; P = .034) and body height (odds ratio, 0.43; 95% confidence interval, 0.29-0.57; P = .041) were independent predictive risk factors for a residual flexion contracture >10°.ConclusionClinicians should be aware that flexed position of the femoral component, particularly in patients of short stature, is associated with increased occurrence of persistent flexion contracture.     

Heterotopic Ossification Negatively Influences Range of Motion After Revision Total Knee Arthroplasty

BackgroundThe incidence of heterotopic ossification (HO) after total knee arthroplasty (TKA) varies and is of unclear clinical significance. This study aimed to identify the incidence of HO in patients undergoing revision TKA for either stiffness or aseptic loosening/instability and determine if the presence of HO is associated with inferior absolute range of motion (ROM) and ROM gains.MethodsEighty-seven patients were prospectively enrolled and separated into 2 cohorts to evaluate ROM after revision TKA (2017-2019). Group 1 (N = 40) patients were revised for stiffness, while group 2 (N = 47) patients were revised for either aseptic loosening or instability. Goniometer-measured ROM values were obtained preoperatively and at 6 weeks, 6 months, and 1 year postoperatively. Statistical analysis included a Fisher’s exact test to assess for an association between preoperative HO and final ROM at 1 year after revision TKA.ResultsHO was identified on preoperative radiographs in 17 patients (20%). There was a significantly higher rate of preoperative HO in patients revised for stiffness compared to patients revised for instability or loosening (30% vs 11%; P = .03). Five cases of HO qualitatively identified as most clinically severe were associated with lower ROM at each time point compared to the remainder of HO cases in this study cohort (P < .02).ConclusionThe presence of HO is greater in patients undergoing revision TKA for stiffness. Additionally, HO severity appears to have a major effect on preoperative and postoperative ROM trajectory. This information should help guide patient expectations and highlight the need for a comprehensive, standardized classification system for HO.     

Partial and Combined Partial Knee Arthroplasty: Greater Anterior-Posterior Stability Than Posterior Cruciate–Retaining Total Knee Arthroplasty

BackgroundLittle is known regarding anterior-posterior stability after anterior cruciate ligament–preserving partial (PKA) and combined partial knee arthroplasty (CPKA) compared to standard posterior cruciate–retaining total knee arthroplasty (TKA).MethodsThe anterior-posterior tibial translation of twenty-four cadaveric knees was measured, with optical tracking, while under 90N drawer with the knee flexed 0-90°. Knees were tested before and after PKA, CPKA (medial and lateral bicompartmental and bi-unicondylar), and then posterior cruciate–retaining TKA. The anterior-posterior tibial translations of the arthroplasty states, at each flexion angle, were compared to the native knee and each other with repeated measures analyses of variance and post-hoc t-tests.ResultsUnicompartmental and bicompartmental arthroplasty states had similar laxities to the native knee and to each other, with ≤1-mm differences throughout the flexion range (P ≥ .199). Bi-unicondylar arthroplasty resulted in 6- to 8-mm increase of anterior tibial translation at high flexion angles compared to the native knee (P ≤ .023 at 80-90°). Meanwhile, TKA exhibited increased laxity across all flexion angles, with increased anterior tibial translation of up to 18 ± 6 mm (P < .001) and increased posterior translation of up to 4 ± 2 mm (P < .001).ConclusionsIn a cadaveric study, anterior-posterior tibial translation did not differ from native laxity after PKA and CPKA. Posterior cruciate ligament–preserving TKA demonstrated increased laxity, particularly in anterior tibial translation.     

Factors Affecting Range of Motion After Revision Total Knee Arthroplasty

BackgroundRange of motion (ROM) after revision total knee arthroplasty (RTKA) is an important clinical outcome, as decreased ROM can lead to patient dissatisfaction and diminished mobility. This study sought to determine the effect of type of revision, implant constraint level, and reason for revision has on RTKA ROM.MethodsA retrospective review of 832 RTKA cases from 2011 to 2019 was conducted at a single, urban academic institution. Patients who underwent aseptic RTKA and had preoperative and 1-year postoperative ROM in their chart were included. The ΔROM was calculated by subtracting the preoperative ROM from the 1-year postoperative ROM. ROM was compared between tibial polyethylene liner-only revisions (liner) and all other revision types (component) and based on reason for revision. Subanalysis was performed within the liner and component revision cohorts to determine the effect of reason for revision and implant constraint level on ROM.ResultsIn total, 290 patients qualified. Forty-two patients had liner revisions (14.5%) and 248 had component revisions (85.5%). The ΔROM for component revision cases was significantly higher than liner exchange only (10° ± 24° vs.1° ± 19°; P = .03). ΔROM was not significant when comparing the level of implant constraint nor was it when separating and comparing by type of revision. Component revisions due to instability were found to significantly decrease ΔROM.ConclusionComponent revision cases have significantly improved ΔROM when compared with liner-only revision. Constraint level is not significantly associated with changes in ROM in either liner or component revisions. Component revisions due to instability significantly reduce ΔROM.     

High Rate of Re-Revision in Patients Less Than 55 Years of Age Undergoing Aseptic Revision Total Knee Arthroplasty

BackgroundThere are limited data on the outcomes of revision total knee arthroplasty in young patients. We sought to characterize the re-revision-free survival and risk factors for re-revision in patients less than 55 years who underwent aseptic revision TKA.MethodsWe retrospectively reviewed 197 revision TKAs at a mean follow-up of 5 years. Mean age was 49 years; mean body mass index was 31 kg/m². Twenty-seven (14%) patients had at least 1 prior revision TKA. The most common indications for revision included instability (29%), arthrofibrosis (26%), and aseptic loosening (24%). Constraint included the following: 59 posterior-stabilized (30%), 123 varus-valgus constrained (62%), and 15 hinged (8%). Components revised included the following: 93 femur/tibia (47%), 68 polyethylene-only (35%), 19 femur-only (10%), and 17 other (9%). Survivorship free from re-revision was calculated via the Kaplan-Meier method and a multivariate Cox proportional regression was utilized to identify risk factors for re-revision.ResultsSurvivorship free from any re-revision at 5 years was 80%. In the multivariate analysis, patients with a prior revision (hazard ratio [HR] = 2.78, P = .02), an isolated polyethylene exchange (HR = 3.0, P = .004), and a hinged prosthesis (HR = 3.47, P = .05) were significant risk factors for lower revision-free survival. Forty-two patients (21%) underwent re-revision, most commonly for periprosthetic joint infection (7%), instability (6%), and aseptic loosening (5%). Re-revision occurred in 18/68 (26%) patients undergoing an isolated polyethylene exchange.ConclusionPatients less than 55 years undergoing revision TKA have a modest 5-year revision-free survival of 80%. Patients with prior revision TKAs (HR = 2.78), hinge type prostheses (HR = 3.47), and polyethylene-only revisions (HR = 3.0) had higher revision rates.     

Acquired Idiopathic Stiffness After Contemporary Total Knee Arthroplasty: Incidence,Risk Factors,and Results Over 25 Years

BackgroundAcquired idiopathic stiffness (AIS) remains a common failure mode of contemporary total knee arthroplasties (TKAs). The present study investigated the incidence of AIS and manipulation under anesthesia (MUA) at a single institution over time, determined outcomes of MUAs, and identified risk factors associated with AIS and MUA.MethodsWe identified 9771 patients (12,735 knees) who underwent primary TKAs with cemented, modular metal-backed, posterior-stabilized implants from 2000 to 2016 using our institutional total joint registry. Mean age was 68 years, 57% were female, and mean body mass index was 33 kg/m². Demographic, surgical, and comorbidity data were investigated via univariate Cox proportional hazard models and fit to an adjusted multivariate model to access risk for AIS and MUA. Mean follow-up was 7 years.ResultsDuring the study period, 456 knees (3.6%) developed AIS and 336 knees (2.6%) underwent MUA. Range of motion (ROM) increased a mean of 34° after the MUA; however, ROM for patients treated with MUA was inferior to patients without AIS at final follow-up (102° vs 116°, P < .0001). Significant risk factors included younger age (HR 2.3, P < .001), increased tourniquet time (HR 1.01, P < .001), general anesthesia (HR 1.3, P = .007), and diabetes (HR 1.5, P = .001).ConclusionAcquired idiopathic stiffness has continued to have an important adverse impact on the outcomes of a subset of patients undergoing primary TKAs. When utilized, MUA improved mean ROM by 34°, but patients treated with MUA still had decreased ROM compared to patients without AIS. Importantly, we identified several significant risk factors associated with AIS and subsequent MUA.Level of EvidenceLevel III, retrospective comparative study.     

Impact of Proximal Tibial Varus Anatomy on Survivorship After Medial Unicondylar Knee Arthroplasty

BackgroundPrecise indications for medial unicondylar knee arthroplasty (UKA) continue to be defined. It is unclear if patients who have proximal tibia vara should be considered candidates for UKA. The purpose of this study was to evaluate the impact of proximal tibial varus alignment on outcomes after UKA.MethodsA retrospective review identified 2,416 patients (3,029 knees) who underwent mobile-bearing medial UKA with 2-year minimum follow-up or revision. Preoperative radiographs were evaluated, and medial proximal tibial angle (mPTA) was measured. Patients were grouped into two groups as follows: mPTA <80 degrees and mPTA ≥80 degrees. Analyses were performed on the impact of mPTA on clinical outcomes, all-cause revisions, and tibial failures.ResultsAt a mean follow-up of 5 years (range, 0.5 years to 12.8 years), there was not a statistically significant difference in clinical outcomes nor increased risk for all-cause revision or tibial failure in patients who had an mPTA <80°. Mean mPTA in patients who had tibial failures was 82.5° and not significantly different than those who did not have a tibial failure (82.9°) (P = .289). Tibial failure rate in knees with an mPTA <80° was 2.2% and not significantly different than knees with an mPTA ≥80° at 1.4% (P = .211). The all-cause revision rate in knees with an mPTA <80° was 5.8% and was not significantly different than knees with an mPTA ≥80° at 4.9% (P = .492).ConclusionPatients who have tibia vara are not at increased risk for tibial related or all-cause failure in medial UKA. This data may allow surgeons to increase their indications for medial UKA.     

Comparison of Modular Conventional and High-Flexion Posterior-Stabilized Total Knee Arthroplasties in the Same Patients at a Mean Follow-Up of 15 Years

BackgroundAs previous studies are limited to short-term clinical data on conventional and high-flexion total knee arthroplasties (TKAs), long-term clinical data on these TKAs remain unclear. Therefore, we evaluated long-term functional outcome, range of knee motion, revision rate, implant survival, and the prevalence of osteolysis after conventional and high-flexion TKAs in the same patients.MethodsThe authors evaluated a cohort of 1206 patients with a mean age of 65.3 ± 7 years (range: 22-70) who underwent bilateral simultaneous sequential TKAs. One knee received a conventional TKA and the other received a high-flexion TKA. The mean duration of follow-up was 15.6 years (range: 14-17).ResultsNo significant differences were found between the 2 groups at the latest follow-up with respect to Knee Society score (93 vs 92 points, P = .765), pain score (45 vs 44 points, P = .641), range of knee motion (125° vs 126°, P = .712), and radiographic and computed tomography scan results. Furthermore, no significant revision rate differences were found between the 2 groups (1.3% for conventional TKA vs 1.6% for high-flexion TKA; P = .137). There was no osteolysis recorded in either group. The rate of survivorship free of implant revision or aseptic loosening was 98.7% (95% CI = 91-100) for conventional TKA and 98.4% (95% CI = 91-100) for high-flexion TKA at 17 years.ConclusionAt the latest follow-up, we were not able to demonstrate any significant difference between conventional and high-flexion TKAs with respect to functional outcome scores, range of knee motion, revision rate, implant survival, and prevalence of osteolysis.     

Posterior-Stabilized TKA in Patients With Severe Genu Recurvatum Achieves Good Clinical and Radiological Results at 5-year Minimum Follow-Up: A Case-Controlled Study

BackgroundGenu recurvatum is a rare knee deformity. Total knee arthroplasty (TKA) in severe preoperative recurvatum requires surgical adjustments. Few studies have assessed the clinical and radiological results of TKA in recurvatum. The aim was to compare the clinical and radiological outcomes, complications, and revision rates after posterior-stabilized TKA in severe recurvatum with those without recurvatum.MethodsBetween 1987 and 2015, 32 primary posterior-stabilized TKA were performed with a preoperative genu recurvatum greater than 10° and minimum follow-up of 60 months. In severe genu recurvatum, the extension gap needs to be decreased compared with flexion gap. To achieve this, the distal femoral cut is distalized, whereas the posterior femoral and tibial cuts are performed as usual. They were compared with 64 matched posterior-stabilized TKAs without recurvatum. The demographic data were similar between groups. The clinical and radiological outcomes, complications, and revision rates were assessed at the last follow-up.ResultsAt a mean follow-up of 7.4 years ± 1.9, there was no significant difference in International Knee Score functional score (77.5 vs. 73.4; P = .50) and knee score (86.6 vs. 89.5; P = .37) between the recurvatum group and the control group, respectively. 6 patients had a postoperative recurvatum equal or superior to 10° in the recurvatum group (18.8%). There was no difference between both groups in radiological outcomes, complication, or revision rates. No instability was found in the recurvatum group.ConclusionPosterior-stabilized TKA with controlled distalization of the femoral component in the setting of severe preoperative genu recurvatum achieves good clinical and radiological outcomes at a minimum follow-up of 5 years and similar to TKA without preoperative recurvatum.Level of EvidenceIII.     

Difference Between Screw Cement Filling and Adequate Osteotomy With Thick Liner for Primary Total Knee Arthroplasty in Patients With Rand IIb Tibial Defects

BackgroundThe effectiveness of 2 treatment options, screw-cement fill, and adequate osteotomy with a thick liner, in treating patients with Rand IIb tibial defects (tibial plateau defects to a depth of 5 to 10 millimeters) in primary total knee arthroplasty (TKA) has not yet been demonstrated. Therefore, we performed a retrospective study to evaluate the differences between these 2 treatments.MethodsWe retrospectively analyzed patients who underwent primary TKA for Rand IIb tibial plateau defects from 2015 to 2020 from a department database. Patients were categorized into the screw-cement and thick liner groups based on the different options used to repair tibial defects. We evaluated Knee Society Score, range of motion (ROM), Insall-Salvati index (ISI), and Forgotten Joint Score (FJS) in both groups. We also compared differences in prosthesis survival, stiffness, myasthenia, and joint clicking between the 2 groups at mean 2 years postoperatively (range, 2 to 2.3). A power analysis was performed on the number of cases in the cohort.ResultsPostoperative femur-tibia mechanical axis (FTMA) correction was significantly higher in the screw-cement group than in the thick-liner group: 18.8 (±5.6°) versus 15.4 (±5.9°) (P < .01); At mean 2 years after surgery, the American Knee Society Functional Score improvement values were higher in the thick-liner group than in the screw-cement group: 36.3 (±12.4) versus 42.4 (±16.4) (P = .05). Postoperative ISI scores were 0.95 (±0.12) points in the screw-cement group and 0.89 (±0.13) points in the-thick liner group (P = .03). There were no statistically significant differences in the Knee Society Clinical Score, ROM, FJS, stiffness, myasthenia, joint clicking, and revision rate.ConclusionThe results of this study showed no significant difference in clinical outcomes between the 2 reconstruction strategies of the screw cement fill technique and the adequate osteotomy and thick liner technique for Rand IIb tibial plateau defects. However, in patients who have FTMA deformities greater than 20° or in younger patients who need to preserve bone volume, we recommend the screw cement filling technique to ensure stable postoperative results and to prepare these patients for possible later surgery.     

Good Postoperative Flexion Angle Improves Knee Function and Improvement of Flexion Angle Increases Patient Satisfaction After Total Knee Arthroplasty

BackgroundTotal knee arthroplasty (TKA) is a well-established procedure for treating knee joint diseases. However, the postoperative range of motion (ROM) varies and is an important indicator of TKA success. Recently, patient-reported outcome measures (PROMs) and patient satisfaction have drawn attention. However, the relationship between ROM and knee function obtained by PROM and satisfaction is not well understood.MethodsWe retrospectively reviewed the data of 375 patients who underwent 500 primary TKA procedures. We measured the ROM before and after surgery. Knee joint function was evaluated using the Knee Injury Osteoarthritis Outcome Score, a PROM, and patients were classified into good function and poor function groups. Patient satisfaction was evaluated on a 5-graded scale as overall satisfaction, and patients were divided into a satisfied or a dissatisfied group according to the obtained scores. ROM was compared between the 2 groups, then significantly different factors were analyzed using multiple logistic regression analysis. Moreover, cut-off points of ROM for obtaining good function and patient satisfaction were determined using ROC curve analysis.ResultsThe postoperative flexion angle had a significant effect on knee function (P < .001). The cut-off value of the postoperative flexion angle for good knee function was 120°. The improvement in flexion angle had a significant effect on patient satisfaction (P = .004). The cut-off value for the improvement in the flexion angle was 5°.ConclusionThe postoperative flexion angle had a significant effect on knee function and improvement in the flexion angle had a significant effect on patient satisfaction.     

Robot-Assisted Total Knee Arthroplasty Does Not Improve Long-Term Clinical and Radiologic Outcomes

BackgroundWhether robot-assisted total knee arthroplasty (TKA) improves the accuracy of radiographic alignment leading to improved patient satisfaction and implant survivorship in the long term has thus far been inconclusive.MethodsWe retrospectively compared the long-term clinical and radiological outcomes of 84 knees that had undergone robot-assisted TKA using ROBODOC vs 79 knees that had undergone conventional TKA. The mean duration of the follow-up period was 129.1 months (range: 108-147 months). Clinical outcomes were evaluated using the Knee Society Score and 36-item Short Form Survey, as well as by assessing the range of motion, operation time, and complications. Radiologic outcomes were evaluated by assessing the hip-knee-ankle angle, coronal and sagittal alignments of the femoral and tibial components, and any radiologic abnormalities such as loosening or osteolysis.ResultsThere was no significant difference in clinical outcomes between the two groups. The prevalence of an outlier for the hip-knee-ankle angle in the robot-assisted group was 10.7%, whereas it was 16.5% in the conventional group (P = .172). The other component alignments (α°, β°, γ°, δ°) revealed a tendency toward a lower rate of outliers in the robot-assisted group, but without statistical significance (P > .05). In addition, there was no significant difference in complications, including revision surgery, between both groups.ConclusionRobot-assisted TKA does not improve long-term clinical or radiologic outcomes compared with conventional TKA.     

A Prospective Randomized Controlled Trial Comparing Medial-Pivot versus Posterior-Stabilized Total Knee Arthroplasty

BackgroundThe medial-pivot (MP) design for total knee arthroplasty (TKA) aims to restore more natural “ball-and-socket” knee kinematics compared to the traditional posterior-stabilized (PS) implants for TKA. The objective of this study is to determine if there was any difference in functional outcomes between patients undergoing MP-TKA vs PS-TKA.MethodsThis prospective randomized controlled trial consisted of 43 patients undergoing MP-TKA vs 45 patients receiving a single-radius PS-TKA design. The primary outcome was postoperative range of motion (ROM). Secondary outcomes included the Western Ontario and McMaster Universities Arthritis Index, Oxford Knee Score, Knee Society Score (KSS), and radiological outcomes. All study patients were followed-up for 2 years after surgery.ResultsPatients undergoing MP-TKA had comparable ROM at 1 year (114.6° ± 16.3° vs 111.3° ± 17.8° respectively, P = .88) and 2 years after surgery (114.9° ± 15.5° vs 114.9° ± 16.4° respectively, P = .92) compared to PS-TKA. There were also no differences in Western Ontario and McMaster Universities Arthritis Index (26.8 ± 19.84 vs 22.0 ± 12.03 respectively, P = .14), Oxford Knee Score (42.7 ± 8.1 vs 42.3 ± 6.7 respectively, P = .18), KSS clinical scores (82.9 ± 16.96 vs 81.42 ± 10.45 respectively, P = .12) and KSS functional scores (76.2 ± 18.81 vs 73.93 ± 8.53 respectively, P = .62) at 2-year follow-up. There was no difference in postoperative limb alignment or complications.ConclusionThis study demonstrated excellent results in both the single-radius PS-TKA design and MP-TKA design. No differences were identified at 2-year follow-up with respect to postoperative ROM and patient-reported outcome measures.