Recovery in knee range of motion reaches a plateau by 12 months after total knee arthroplasty

Impact of Range of Motion Trajectory on Patient-Reported Outcomes Following Total Knee Arthroplasty

BACKGROUND

Postoperative knee range of motion (ROM) is among the most frequently reported functional metrics following total knee arthroplasty (TKA). Despite the major use of ROM as a metric, minimal literature exists assessing the progression of motion postoperatively over time or its implications on patient-reported outcome measures (PROMs). As such, this study aimed to (1) determine the recovery trajectory in knee ROM during the first year following primary TKA and (2) determine if a correlation existed between patients' ROM recovery trajectory and PROM scores.

METHODS

Data was collected prospectively on all patients undergoing a unilateral primary TKA between 2017 and 2019. Standardized goniometric measurements were used to measure knee flexion and extension at five time points: preoperatively, intraoperatively, and postoperatively at two weeks, six weeks, and one year. In addition, the Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS-JR) was collected preoperatively and at the one-year postoperative visit. A total of 306 TKA procedures were performed on 269 patients, and of those patients, 63.9% (N = 172) were women and 36.1% (N = 97) were men who had a mean age of 67 years (range, 29.0 to 89.4) and a mean body mass index (BMI) of 30.8 (range, 18.2 to 49.0).

RESULTS

Mean knee flexion significantly increased from 112.8 (range, 63.0 to 140.0) degrees preoperatively to 119.0 (range, 95.0 to 140.0) degrees at one year postoperatively (mean difference = 4.61, P < 0.001). More specifically, 97.4% of flexion was restored by six weeks (111.2; range, 58.0 to 132.0) postoperatively. Knee extension also significantly improved from 5.9 (range, -5.0 to 32.0) degrees to 0.9 (range, 0 to 8.0) degrees at one-year follow-up (mean difference = 5.03, P < 0.001). A weak positive correlation existed between preoperative ROM and KOOS JR scores (r = 0.24, P < 0.01).

CONCLUSION

Knee flexion ROM is restored in a nonlinear trajectory following a primary TKA, with over 90% of the progress occurring within the first six weeks postoperatively. In contrast, knee extension ROM is restored in a more linear manner. At one year postoperatively, target ROM fell between preoperative and intraoperative measurements. Neither ROM nor the recovery trajectory of motion correlates with KOOS-JR scores. As such, this information can be valuable when attempting to set expectations for patient recovery.

Volume and Distribution of Early Knee Effusion After TKA with a PEEK-Based Knee Prosthesis: Correlation with Changes in Serum Inflammation Marker Levels, Knee Functional Score, and Range of Motion

BACKGROUND

Early knee effusion is a common phenomenon after total knee arthroplasty (TKA), with potential clinical implications. Unlike traditional alloy knee prostheses, the polyetheretherketone (PEEK) knee system has radiographic transparency on magnetic resonance (MR) scans, which allows analysis of prosthetic knee effusion. We aimed to identify the distribution and volume of knee effusion after TKA with the PEEK prosthesis with use of MR imaging and to analyze whether dynamic changes in effusion were correlated with serum inflammatory marker changes and knee function recovery.

METHODS

Nine patients with osteoarthritis who were 59 to 74 years old underwent unilateral TKA with the PEEK prosthesis between June 2021 and August 2021. Dynamic early postoperative changes in the volume and distribution of knee effusion were evaluated with use of 3D MR stereoscopic images. Serum inflammatory markers were measured via blood tests, and joint function was evaluated with use of the subjective functional score of the Knee Society Score (KSS) and knee range of motion (ROM). Linear regression analyses were performed to assess for correlations between knee effusion volume and inflammatory markers and between knee effusion volume and joint function.

RESULTS

The mean serum inflammatory marker levels increased significantly at 1 week after TKA with the PEEK prosthesis and then gradually decreased with time from 1 to 6 months. The mean total knee effusion volume gradually decreased over time. Concurrently, the mean KSS subjective functional score and mean knee ROM improved with time. Total knee effusion volume was positively correlated with C-reactive protein level (R2 = 0.16; p = 0.007) and negatively correlated with the change in KSS score between the preoperative and postoperative time points (R2 = 0.19; p = 0.003). Using the 1-week total knee effusion volume as a reference, a positive correlation was observed between the reduction in total knee effusion volume and the actual value of the ROM (R2 = 0.36; p = 0.0001) from 3 to 24 months postoperatively.

CONCLUSIONS

Through 3D MR imaging, the precise distribution and volume of, and dynamic changes in, knee effusion after TKA with the PEEK prosthesis were confirmed and were found to be correlated with inflammation and joint function in the early postoperative period. The results demonstrate the potential clinical benefit of the PEEK-based knee system for future use.

LEVEL OF EVIDENCE

Diagnostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Development and Validation of a Mobile Phone Application for Measuring Knee Range of Motion

Knee range of motion (ROM) is an important indicator of knee function. Outside the clinical setting, patients may not be able to accurately assess knee ROM, which may impair recovery following trauma or surgery. This study aims to validate a smartphone mobile application developed to measure knee ROM compared to visual and goniometer ROM measurements. A knee ROM Android mobile application was developed to measure knee ROM. Patients ≥ 18 years old presenting to an orthopaedic clinic with native knee complaints were approached to participate. Knee ROM was measured bilaterally by an arthroplasty-trained surgeon using (1) vision, (2) goniometer, and (3) the mobile application. Measurements were compared in flexion and extension using a one-way analysis of variance with post hoc Tukey test (alpha = 0.05). Eighty-four knee ROM measurements (40 left, 44 right) were obtained in 47 patients. Median Kellgren-Lawrence grade from available radiographs was grade 3. In flexion, mobile application (117.6 ± 14.7 degrees) measurements were not significantly different from visual (116.1 ± 13.6 degrees) or goniometer (116.2 ± 13.6 degrees) measurements. In extension, mobile application (4.8 ± 7.3 degrees) measurements were significantly different from visual (1.9 ± 4.1 degrees) measurements on post hoc analysis (p < 0.01), while no differences were present compared to goniometer (3.1 ± 5.8 degrees) measurements. Our study found that a mobile application for evaluating knee ROM was noninferior to goniometer-based measurements performed by an arthroplasty-trained surgeon. Future studies will investigate this application's utility in (1) remote patient care, (2) accelerating recovery during rehabilitation, (3) detecting early postoperative complications including arthrofibrosis, and (4) adding additional functionalities to the application to provide more detail-oriented descriptive analyses of patient knee function.

Validity of wearable sensors for total knee arthroplasty (TKA) rehabilitation: A study in younger and older healthy participants

BACKGROUND

With 100,000 total knee arthroplasty (TKA) procedures taking place in the United Kingdom annually, the demand on rehabilitation services is high. Most regimes are home-based. Without clinician-patient interaction, detection of rehabilitation concerns can be delayed, reducing the chance of successful early intervention. Wearable technologies, such as MotionSenseTM (Stryker, US), may offer a solution to this problem by remotely supporting post-operative TKA rehabilitation through the provision of personalised rehabilitation and tracking of home exercises, enabling healthcare professionals to continuously monitor rehabilitation progress remotely. Validation of such devices against a known kinematic model in activities of daily living is important for confident interpretation of resulting clinical data. The aim of this study therefore was to validate the accuracy of MotionSenseTM against a clinical motion capture standard.

METHODS

Twenty younger and 14 older healthy, able-bodied adults attended one testing session (Younger: 24 ± 4 years old; Older: 71 ± 5 years old). Movement was tracked using Vicon motion analysis and a Plug-In-Gait lower body model was applied to all participants. Three activities were performed - walking, stair ascent, stair descent. The knee flexion angle root mean square error (RMSE) between the technologies was determined.

RESULTS

For both groups the knee flexion RMSE remained below 3° for all activities. The combined RMSE for all adults was 2.4° for walking, 2.7° for stair ascent, and 2.6° for stair descent. The signed error increased during the swing phase of gait.

CONCLUSION

MotionSenseTM was found to accurately estimate knee flexion angles during several common activities compared to Vicon motion capture.

When does patient function "Plateau" after total joint arthroplasty? A cohort study

PURPOSE

With over 100,000 procedures completed per year, hip and knee arthroplasty are two of the most common surgical procedures performed in Canada. There has been literature indicating that patient reported outcome measures (PROM) will start to plateau between six and 12 months. The purpose of this paper was to analyze the trajectory of PROMs following total hip and knee arthroplasty (THA and TKA), as well as assess the impact of any potential confounders on this trajectory. The central research question was: At what point do PROMS plateau among patients that undergo elective THA and TKA?

METHODS

This study was a retrospective analysis of data from a prospective database. Patients were eligible if they had undergone an elective, primary THA/TKA with Oxford Scores recorded pre-operatively, and at least at two of the following four time points: six weeks, six months, one year, and two years.

RESULTS

Mean pre-operative Oxford scores were 18.0 (7.8) for THA, and 20.1 (7.5) for TKA. For both THA and TKA, there were statistically significant interval improvements in Oxford scores from six weeks [THA: 33.8 (7.9)/TKA: 28.7 (7.8)] to six months [THA: 40.2 (7.3)/TKA: 35.9 (8.3)], and from six months to one year [THA: 41.0 (7.3)/TKA: 37.3 (8.4)], but not from one to two years [THA: 40.0 (8.5)/TKA: 36.4 (9.6)].

CONCLUSIONS

Patients undergoing either primary THA or TKA can expect clinically meaningful improvements in the first six months after surgery. Beyond this time point, there is a plateau in PROMs. These findings are important for both setting patient expectations in pre-operative discussions, and allowing surgeons to have a realistic understanding of their patients' expected post-operative course.

Evaluating two implant designs in patients undergoing primary total knee arthroplasty using a novel measure of early optimal recovery: a retrospective observational study

PURPOSE

Quality of care in total knee arthroplasty (TKA) between implants was assessed using a novel composite outcome measure, early optimal recovery (EOR), to indicate ideal clinical outcomes and minimal healthcare resource utilization.

METHODS

Patients that underwent primary TKA in the study group (ATTUNE® Knee System) or control group (LCS® COMPLETE Knee System) were included in this retrospective, single-center study. EOR was defined as no complications, no readmissions, no extra outpatient visits, ≤ 48 h length of hospital stay (LOS), and restored range of motion and pain perception at 3-month follow-up. Multivariate logistic regression was used to compare EOR between the study and control groups. Results were adjusted for differences in baseline characteristics and are presented with 95% confidence intervals (CI). Data were collected from a specialized clinic for elective surgeries in the Netherlands, between January 2017 and December 2020.

RESULTS

A total of 566 patients (62.4% female, mean age 67 years) were included for analysis; 185 patients (32.7%) underwent TKA in the study group. Compared to the control group, patients in the study group had greater probability of achieving EOR (65.8% [95% CI: 55.1-75.2] vs. 38.9% [95% CI: 32.8-45.3]; p < 0.001), a LOS ≤ 48 h (77.2% [95% CI: 67.7-84.5] vs. 61.4% [95% CI: 54.7-67.7]; p < 0.05), and ideal pain perception at 3-month follow-up (93.3% [95% CI: 85.7-97.0] vs. 78.2% [95% CI: 71.0-83.9]; p < 0.05).

CONCLUSION

The study group was associated with a greater probability of achieving EOR versus the control group, suggesting improved quality of care.

Device-Measured Physical Activity in 3506 Individuals with Knee or Hip Arthroplasty

PURPOSE

Hip and knee arthroplasty aims to reduce joint pain and increase functional mobility in patients with osteoarthritis; however, the degree to which arthroplasty is associated with higher physical activity is unclear. The current study sought to assess the association of hip and knee arthroplasty with objectively measured physical activity.

METHODS

This cross-sectional study analyzed wrist-worn accelerometer data collected in 2013-2016 from UK Biobank participants (aged 43-78 yr). Multivariable linear regression was performed to assess step count, cadence, overall acceleration, and activity behaviors between nonarthritic controls, end-stage arthritic, and postoperative cohorts, controlling for demographic and behavioral confounders. From a cohort of 94,707 participants with valid accelerometer wear time and complete self-reported data, electronic health records were used to identify 3506 participants having undergone primary or revision hip or knee arthroplasty and 68,389 nonarthritic controls.

RESULTS

End-stage hip or knee arthritis was associated with taking 1129 fewer steps per day (95% confidence interval (CI), 811-1447; P < 0.001) and having 5.8 fewer minutes per day (95% CI, 3.0-8.7; P < 0.001) of moderate-to-vigorous activity compared with nonarthritic controls. Unilateral primary hip and knee arthroplasties were associated with 877 (95% CI, 284-1471; P = 0.004) and 893 (95% CI, 232-1554; P = 0.008) more steps than end-stage osteoarthritic participants, respectively. Postoperative unilateral hip arthroplasty participants demonstrated levels of moderate-to-vigorous physical activity and daily step count equivalent to nonarthritic controls. No difference in physical activity was observed between any cohorts in terms of overall acceleration, or time spent in daily light activity, sedentary behavior, or sleep.

CONCLUSIONS

Hip and knee arthroplasties are associated with higher levels of physical activity compared with participants with end-stage arthritis. Unilateral hip arthroplasty patients, in particular, demonstrate equivalence to nonarthritic peers at more than 1 yr after surgery.

Improved postoperative kneeling ability in posterior stabilized total knee arthroplasty with medialized dome-patella resurfacing: A retrospective comparative outcome analysis

OBJECTIVES

This investigation aimed to evaluate if the modifications to prosthesis designs improve patients' clinical and functional outcomes after total knee arthroplasty (TKA), with a special focus on pain and kneeling ability.

METHODS

Retrospective and comparative analysis of consecutive patients who were treated with posterior stabilized TKA using two different prostheses designs (single surgeon, single vendor). Group 1 received a traditional design TKA (PFC Sigma; DePuy, Inc., Warsaw, IN) with conventional dome-patella resurfacing, and group 2 received a modern design implant (Attune; DePuy, Inc., Warsaw, IN) with medialized dome-patella resurfacing. Functional outcome (range of motion: ROM) and the Oxford Knee Score (OKS) were collected preoperatively, at 4-6 weeks and 12 months following surgery.

RESULTS

Ninety-nine participants were included. Of these, 30 received traditional-design implants and 69 received modern-design knee implants. The comparison between the two implants showed a statistically significant increase in total OKS and kneeling ability in the modern design cohort at 1-year follow-up compared to the traditional design cohort (p ​< ​0.01). In the modern design group, 53% (N ​= ​37) could kneel easily or with little difficulty, compared to 30% (N ​= ​9) in the traditional design group. No statistically significant differences in ROM or the OKS pain component were seen.

CONCLUSION

The incorporation of a medialized dome-patella in modern knee implant design may offer advantages over traditional designs, as seen in improved total OKS and kneeling ability at one-year follow-up. Further research with larger cohorts is needed to confirm these findings and explore the broader impact of implant design changes on patient outcomes.

LEVEL OF EVIDENCE

Clinical Study, Level III.

The role of a cryocompression device following total knee arthroplasty to assist in recovery: a randomised controlled trial

PURPOSE

The study sought to investigate the effectiveness of a cryocompression Game Ready™ (GR) versus usual care protocol (UC) on early post-operative recovery following total knee arthroplasty.

METHODS

This study prospectively randomised 72 total knee arthroplasties to a 2-week (from day 0) intervention of GR treatment (n = 36, 63.9% females) or UC of ice with static compression (n = 36, 45.7% females). Knee flexion and extension range of motion (ROM), a visual analogue pain scale and limb circumference were documented at day 1, 2 and 14, as well as 6 weeks post-surgery. Medication usage and length of hospital stay were documented. Patient-reported outcome measures (PROMs) included the Knee Injury and Osteoarthritis Outcome Score and a Patient Satisfaction Questionnaire. Statistical analysis using linear mixed modelling and analysis of variance table with Satterthwaite's method were used along with two-tailed t-tests.

RESULTS

There were no significant group-by-time interactions regarding any of the outcomes. The GR group had 19% lost to follow-up at 2 weeks, while the UC group had 8%. The GR group demonstrated significantly better knee extension ROM at day 1 (p = 0.048) and day 14 (p = 0.007) compared with the UC group. There were no group differences (n.s.) observed in pain, flexion ROM, limb circumference, opioid use or PROMs. Overall, higher pain levels resulted in increased opioid intake (p = 0.002), older patients used significantly less opioids (p < 0.001) and males reported significantly less pain than females (p = 0.048). No adverse effects were observed due to either protocol.

CONCLUSION

Despite patients gaining significantly more knee extension during the initial two-week intervention period when using GR compared to UC, this effect was likely due to chance. No further significant differences were observed between the groups during or after cession of the intervention.

LEVEL OF EVIDENCE

Level 2.

Prospective, Randomized Clinical Trial Comparing a Novel Motion-Assistive Device to Standard Physical Therapy for Initial Management of Knee Range of Motion after Primary Total Knee Arthroplasty

This prospective randomized clinical trial assessed a novel device for initial management of knee range of motion (ROM), pain, and function after total knee arthroplasty (TKA). Primary TKA patients with preoperative ROM of at least 5° to 115° were randomized to initial knee motion management: Mizzou BioJoint Flex-novel motion-assistive device with prescribed physical therapy or standard physical therapy-prescribed physical therapy. ROM, pain score, and knee injury and osteoarthritis score for joint replacement (KOOSjr) were obtained preoperatively and 2 weeks, 6 weeks, and 3 months postoperatively. Patient satisfaction for both cohorts and subjective assessments of the MBF device were assessed at 3 months. Readmissions, reoperations, and complications were assessed through 1 year. Nineteen patients were randomized to each cohort, with no significant preoperative differences in demographics, pain score, KOOSjr score, or ROM. Six SPT (31.6%) and 3 MBF (15.8%) patients failed to regain preoperative ROM (p = 0.044). One SPT (5.3%) and eight MBF (42%) patients exceeded 125° ROM (p = 0.019) by 3 months. Total ROM (p = 0.039), pain (p = 0.0068), and function (p = 0.0027) were significantly better for MBF at 3 months. MBF patients reported significantly higher satisfaction (mean, 9.4 ± 1.1 vs. 8.0 ± 1.8, respectively; p = 0.0084). One patient in each group underwent manipulation under anesthesia. No other readmissions, reoperations, or complications were reported. A novel durable medical equipment device can provide a safe and effective patient-controlled method for initial management of knee ROM, pain, and function after primary TKA with potential clinically meaningful advantages over physical therapy alone. In conjunction with physical therapy, management with this novel knee flexion device more effectively restored knee ROM and early patient function when compared with therapy alone and was associated with higher proportions of patients regaining minimum (115°) and desired (125°) levels of knee ROM and clinically meaningful differences in pain scores, knee function, and patient satisfaction. This is a Level 1, prospective trial study.

The pre-anesthetic period is the best time to evaluate the knee flexion angle for predicting the flexion angle after total knee arthroplasty: A prospective cohort study

INTRODUCTION

Knee flexion angle (KFA) is one of the most critical factors for evaluating patient functional outcomes after total knee arthroplasty (TKA). Preoperative KFA and intraoperative drop leg test are both accepted as predictors of postoperative KFA after TKA. Preoperative testing performed after anesthesia helps overcome pain-related limitations; however, the KFA measurement timepoint that best predicts KFA at 6 months after TKA has not yet been established.

METHODS

This prospective cohort study recruited patients who underwent unilateral primary TKA at Siriraj Hospital (Bangkok, Thailand) during August 2012 to August 2017. We recorded KFA at the pre-anesthetic phase, post-anesthetic phase, intraoperation using drop leg test, and at 6-months post-operation. Pearson's correlation coefficient was used to evaluate correlation between different measurement timepoints and 6 months after surgery. Those same relationships were evaluated for overall patients, and for patients with KFA <90° (poor KFA), 90-120° (average KFA), and >120° (high KFA).

RESULTS

A total of 165 patients with a mean age of 68.7 years were recruited. Pre-anesthetic KFA measurement had the highest positive correlation with the 6-month KFA (r = 0.771, p<0.05). Post-anesthetic measurement and intraoperative drop leg KFA measurement had moderate positive correlation (r = 0.561, p<0.05) and low positive correlation (r = 0.368, p<0.05) with the 6-month KFA, respectively. The average KFA group had the highest positive correlation between pre-anesthetic KFA measurement and the 6-month KFA (r = 0.711, p<0.05). Predicted 6-month KFA (degrees) adjusted for pre-anesthetic KFA is 45.378 + [0.596 x pre-anesthetic KFA (degrees)] (r = 0.67, p <0.05).

CONCLUSIONS

Pre-anesthetic KFA demonstrated the highest correlation with the final KFA at six months after unilateral primary TKA, especially in the patients who had a preoperative KFA within 90-120°.

Acute postoperative pain and dorsal root ganglia transcriptomic signatures following total knee arthroplasty (TKA) in rats: An experimental study

Total knee arthroplasty (TKA) is the final treatment option for patients with advanced knee osteoarthritis (OA). Unfortunately, TKA surgery is accompanied by acute postoperative pain that is more severe than arthroplasty performed in other joints. Elucidating the molecular mechanisms specific to post-TKA pain necessitates an animal model that replicates clinical TKA procedures, induces acute postoperative pain, and leads to complete functional recovery. Here, we present a new preclinical TKA model in rats and report on functional and behavioral outcomes indicative of pain, analgesic efficacy, serum cytokine levels, and dorsal root ganglia (DRG) transcriptomes during the acute postoperative period. Following TKA, rats exhibited marked deficits in weight bearing that persisted for 28 days. Home cage locomotion, rearing, and gait were similarly impacted and recovered by day 14. Cytokine levels were elevated on postoperative days one and/or two. Treatment with morphine, ketorolac, or their combination improved weight bearing while gabapentin lacked efficacy. When TKA was performed in rats with OA, similar functional deficits and comparable recovery time courses were observed. Analysis of DRG transcriptomes revealed upregulation of transcripts linked to multiple molecular pathways including inflammation, MAPK signaling, and cytokine signaling and production. In summary, we developed a clinically relevant rat TKA model characterized by resolution of pain and functional recovery within five weeks and with pain-associated behavioral deficits that are partially alleviated by clinically administered analgesics, mirroring the postoperative experience of TKA patients.

Clinical usefulness and safety in the early phase after a newly designed rotating-platform total knee arthroplasty: A prospective multicentre cohort study with a 2-year follow up

BACKGROUND

This study aimed to assess the clinical results and safety of a newly designed rotating-platform posterior-stabilised total knee arthroplasty (TKA) in the early postoperative phase, within 2 years of follow up.

METHODS

This prospective, multicentre cohort study included 100 consecutive patients who underwent rotating-platform posterior-stabilised (PS) TKA (Vanguard PSRP). After excluding dropouts, 93 patients were analysed. The objective Knee Society Score (KSS)-2011, subjective KSS-2011, knee range of motion, EuroQol 5 Dimension index, complications, and survival rates were assessed before TKA and at 6 months, 1 year, and 2 years postoperatively. The scores at each time-point were compared, and the survival rate was assessed with revision as the endpoint. To demonstrate non-inferiority, the clinical outcomes of patients who underwent rotating-platform PS TKA were compared with those collected retrospectively from 50 patients who underwent fixed-PS TKA (Vanguard PS), defined as the control group.

RESULTS

All clinical outcomes at the final follow up significantly improved compared with their preoperative values (P < 0.001). The objective KSS-2011 was 90.0 ± 8.2 points, subjective KSS-2011 satisfaction was 30.7 ± 8.6 points, expectation was 10.4 ± 2.1 points, and functional activity was 74.0 ± 18.5 points at 2 years postoperatively. Complications included knee dislocation in one patient and surgical site infection in one patient. The survival rate was 99% at 2 years postoperatively. Clinical outcomes, complications, and survival rates of newly designed TKA were not statistically different compared with the control group.

CONCLUSION

The newly designed rotating-platform PS TKA showed good clinical results and suitable safety during the early postoperative phase in this prospective multicentre cohort study.

Extension Contracture Stiff Knee in Haemophilia: Surgical Timing and Procedure for Total Knee Arthroplasty

INTRODUCTION

Total knee arthroplasty (TKA) for a stiff knee of patients with hemophilia (PWH) represents a challenge for orthopaedic surgeons for the difficulties of exposing the knee and high complication rate compared to a flexible knee.

AIM

To optimize the surgical exposure in primary TKA for PWH, and to propose a threshold angle of extension contracture in treating haemophilic knee joints, retrospectively.

METHODS

67 primary TKAs for PWH (mean age, 48 years) were performed, and incisional approaches to joint were standard (58 cases) and V-Y quadricepsplasty (V-Y) (9 cases). The decision of surgical approach was decided intraoperatively by two surgeons. Pre and post knee angles were evaluated in each group. Variables in the V-Y group were evaluated using univariate logistic regression analysis and receiver operating characteristic (ROC) curve analysis.

RESULTS

Univariate logistic regression analysis demonstrated that preoperative range of motion (ROM) and flexion were significantly associated with V-Y. Threshold values of preoperative flexion and ROM resulting in V-Y using ROC analysis were 45°and 35°.

CONCLUSIONS

Primary TKA for PWH using a standard approach may be performed before the stage preoperative flexion <45° and ROM <35°.

Clinical Course of Pain and Function Following Total Knee Arthroplasty: A Systematic Review and Meta-Regression

BACKGROUND

Total knee arthroplasty (TKA) is widely considered a successful intervention for osteoarthritis and other degenerative knee diseases. This study addresses the need for a high-quality meta-analysis that outlines the clinical course of pain and function post-TKA.

METHODS

The review included prospective cohort studies assessing pain or function of patients undergoing primary TKA at baseline (preoperatively) and at least 2 additional time points including one at least 12 months postoperatively. Two reviewers independently screened references, extracted data, and assessed risk of bias using the Quality in Prognosis Studies tool. The time course of recovery of pain and function was modeled using fractional polynomial meta-regression.

RESULTS

In total, 191 studies with 59,667 patients were included, most with low risk of bias. The variance-weighted mean pain score (/100, 0 = no pain) was 64.0 (95% confidence interval [CI] 60.2-67.7) preoperatively, 24.1 (95% CI 20.3-27.9) at 3 months, 20.4 (95% CI 16.7-24.0) at 6 months, and 16.9 (95%CI 13.6-20.3) at 12 months, and remained low (10.1; 95% CI 4.8-15.4) at 10 years postoperatively. The variance-weighted mean function score (/100, 0 = worst function) was 47.1 (95% CI 45.7-48.4) preoperatively, 72.8 (95% CI 71.3-74.4) at 3 months, 76.3 (95% CI 74.7-77.8) at 6 months, and 78.1 (95%CI 76.4-79.7) at 12 months. Function scores were good (79.7; 95% CI 77.9-81.5) at 10 years postoperatively.

CONCLUSION

Patients undergoing primary TKA can expect a large and rapid but incomplete recovery of pain and function in the first postoperative year. At 10 years, the gains in pain scores may still remain while there is an improvement in function.

Improvements in functional outcome and quality of life are not sustainable for patients ≥ 68 years old 10 years after total knee arthroplasty

PURPOSE

The aims of this study are to evaluate whether improvements in functional outcome and quality of life are sustainable 10 years after total knee arthroplasty (TKA), and the age cut-off for clinical deterioration in outcomes METHODS: Prospectively collected registry data of 120 consecutive patients who underwent TKA at a tertiary hospital in 2006 was analysed. All patients were assessed at 6 months, 2 years and 10 years using the Knee Society Function Score, Knee Society Knee Score, Oxford Knee Score, Short-Form 36 Physical/Mental Component Scores and postoperative satisfaction. One-way ANOVA was used to compare continuous variables, while Chi-squared test to compare categorical variables. Multivariate logistic regression and receiver operating curve analysis was performed to evaluate the predictive factors associated with deterioration of scores postoperatively.

RESULTS

Significant improvements were noted in all functional outcome and quality of life scores at 6 months after TKA. Between 6 months and 2 years, the KSFS and OKS continued to improve but the KSKS, PCS and MCS plateaued. Between 2 and 10 years, there was a deterioration in the KSFS and OKS, whilst KSKS, PCS and MCS were maintained. Increasing age was noted to be a significant risk factor for deterioration of KSFS at 10 years with age ≥ 68 as the cut-off value. 91.7% of patients with KSFS Minimally Clinically Important Difference(MCID) (≥ 7 points) continued to be satisfied after 10 years compared to 100.0% who did not experience KSFS MCID deterioration (p = 0.02).

CONCLUSION

Patients ≥ 68 years experience deterioration in functional outcomes and quality of life from 2 to 10 years after TKA.

LEVEL OF EVIDENCE

Retrospective study, Level III.

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

BACKGROUND

Total 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.

METHODS

We 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.

RESULTS

The 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°.

CONCLUSION

The postoperative flexion angle had a significant effect on knee function and improvement in the flexion angle had a significant effect on patient satisfaction.

Midterm functional recovery of Total knee arthroplasty patients compared between the ATTUNE knee system and the press fit condylar (PFC) SIGMA knee system

BACKGROUND

The ATTUNE Knee System is a new prosthetic design that has theoretical advantages over the Press Fit Condylar (PFC) Sigma Knee System specific to improved knee kinematics and patellofemoral joint tracking. This study aimed to evaluate functional outcomes compared between the ATTUNE and PFC Sigma designs at a minimum follow-up of 5 years.

METHODS

We retrospectively reviewed data from total knee arthroplasty (TKA) patients who received either the ATTUNE or PFC Sigma system during November 2013 to February 2015 at Siriraj Hospital (Bangkok, Thailand). Functional outcomes were evaluated using Timed Up and Go (TUG) test, 2-min walk test (2MWT), modified knee score, numerical rating scale-pain, range of motion (ROM), and rate of anterior knee pain and crepitation at preoperation, 3-months, 1-year, and 5-years postoperatively.

RESULTS

Of 113 patients, 59 and 54 received the PFC Sigma and ATTUNE systems, respectively. At a minimum of 5-years follow-up, all functional outcomes improved significantly from the preoperative period although TUG test and 2MWT declined significantly from 1- to 5-years postoperatively only in the PFC Sigma group. The mean ROM at 5-years postoperatively was significantly higher in ATTUNE than in PFC Sigma; however, the difference was small (116° vs. 110°, respectively; p = 0.041). There were no significant differences in any of the other outcome measurements, including anterior knee pain, clunking, and crepitation, between groups at any study time point.

CONCLUSIONS

​Our results revealed no major differences in functional outcomes between the PFC Sigma and ATTUNE TKA designs at an intermediate-term follow-up of at least 5 years. Longer-term follow-up study is needed to evaluate the benefits of the ATTUNE design relative to polyethylene wear and the rate of aseptic loosening.

Importance of knee flexion range of motion during the acute phase after total knee arthroplasty

BACKGROUND

We investigate the association with knee flexion range of motion (ROM) during the acute phases and that at 12 months after total knee arthroplasty (TKA). We also clarified the cut-off ROM during the acute phases in predicting the goal of knee flexion ROM at 12 months.

METHODS

In this retrospective study, 193 patients with knee osteoarthritis (female:144 patients, age:73.2 ± 7.7 years) who underwent unilateral TKA at an orthopedic clinic were recruited. They underwent assessments of knee flexion ROM at 5 days, 1 month, and 12 months after TKA. The goal of knee flexion ROM at 12 months after TKA was set at 120°. Single and logistic-regression analyses were performed with the dependent variables including the outcome of the goal of knee flexion ROM at 12 months, and the independent variables included knee flexion ROM at 5 days and 1 month, separately. We calculated the cut-off ROM at 5 days and 1 month for predicting the goal of knee flexion ROM at 12 months with receiver operating curve analysis.

RESULTS

Knee flexion ROM at 5 days and 1 month were significantly associated with the goal of that at 12 months (p < 0.01). The cut-off ROM were 85° at 5 days and 105° at 1 month separately.

CONCLUSIONS

Our results suggest the importance of early improvement in knee flexion ROM after TKA, and that at 1 month postoperatively indicates the likelihood of achievement of the goal of knee flexion ROM at 12 months after TKA.

Feasibility and efficacy of knee extension training using a single-joint hybrid assistive limb, versus conventional rehabilitation during the early postoperative period after total knee arthroplasty

Objectives: To evaluate the feasibility and efficacy of treatment for the recovery of knee joint function after total knee arthroplasty (TKA) using a robotic suit.

Patients and Methods: Knee joint extension exercise sessions were started with a robotic suit (single-joint hybrid assistive limb [HAL-SJ, Cyberdyne, Inc., Tsukuba, Japan]) in one group of patients after TKA. Patients who underwent standard rehabilitation were enrolled in the control group. To evaluate feasibility and safety, we assessed the adverse events, the number of training sessions, and training time. We compared the changes in knee joint pain and extension lag (°) between the groups.

Results: The average age was 71.3 ± 6.2 years in the HAL-SJ group and 74.9 ± 8.7 years in the control group. There were no severe adverse events. In the HAL-SJ group, training was performed 2.9 times, on average, and lasted 18.8 min. In the HAL-SJ group, there was a reduction in the visual analog scale (VAS) for pain after training, which was not significant. In the control group, the VAS score worsened after the sessions. The extension lag significantly improved in the HAL-SJ group after the 2nd and 3rd sessions, and this was more due to improvements in their active extension range of motion than their passive extension range of motion.

Conclusions: HAL-SJ-based training is safe and effective, and leads to instantaneous improvement of extension lag, without worsening knee joint pain. HAL-SJ-based knee extension training could represent a viable novel post-TKA rehabilitation modality.

Changes in knee range of motion after large osteochondral allograft transplantations

BACKGROUND

Our study purpose was to determine if primary osteochondral allograft (OCA) transplant surgeries for large (>4 cm²) single-surface, multisurface, or bipolar articular defects in the knee would be associated with significant gains in knee range of motion (ROM) at ≥1-year follow-up when compared to preoperative ROM.

METHODS

Patients were prospectively enrolled into a dedicated registry to follow outcomes after OCA with or without meniscal allograft transplantation using Missouri Osteochondral Preservation System (MOPS)-preserved allografts. Patients were included if they had surgery to repair at least one osteochondral defect, and when at least one year of ROM data and Visual Analog Scale pain scores were available. Data on complications and reoperations, patient-reported outcome measures, compliance with rehabilitation, revisions, or failures were recorded.

RESULTS

For patients who met inclusion criteria after OCA surgery (n = 75), overall ROM increased from 127.8 ± 17 degrees preoperatively, to 130.5 ± 14 post-operatively. Non-compliance was the largest factor contributing to postoperative ROM lag or loss. Knee manipulation/lysis of adhesion rates were comparable to rates in TKA and ACL procedures (2.96-4.54% for ACL/TKA, 4% for OCAs in the present study).

CONCLUSION

Results suggest that OCA with or without meniscal allograft transplantation in the knee using high-viability grafts, advanced graft cutting and implantation techniques, and procedure-specific rehabilitation protocols can result in consistently successful outcomes in a high percentage (92%) of selected patients. Most patients (95%) can expect to regain, or improve, to "full" functional range of motion (130°) at 1 year after surgery such that highly functional activities can be performed.

LEVEL OF EVIDENCE

Cohort study; Level III.

Which factors affect the ability to kneel following total knee arthroplasty? An outpatient study of 100 postoperative knee replacements

BACKGROUND

Kneeling is an important activity of daily living, holding social, religious and occupational value. Following total knee replacement (TKR), many patients report they are unable to kneel or have been advised not to kneel.

METHODS

We observed 100 consecutive knee replacements in 79 patients attending outpatient clinic at a minimum 5 months post-TKR. The patients were asked to fill out a questionnaire detailing whether they were able to kneel prior to their knee replacement and whether they thought they were able to kneel since their knee replacement. The patients were then asked to kneel on a padded examination couch and then onto a pillow on the floor for 15 s. Degree of flexion achievable was also recorded.

RESULTS

Of the knees with patella resurfacing, 78.6% were able to kneel compared to only 45.6% knees with native patellae. Two-tailed Fisher's exact test showed this difference to be statistically significant (p = 0.001). The χ² analysis showed that those patients with an achievable flexion of angle of greater than 100° were significantly more likely to be able to kneel than those with a flexion angle of less than 100° (p = 0.0148). Comparing posterior cruciate ligament (PCL) retaining against PCL sacrificing implants, there was no statistically significant difference in kneeling ability (p = 0.541).

CONCLUSION

Kneeling remains an important function in patients undergoing TKR, with patella resurfacing significantly improving the likelihood of a patient being able to kneel.

Functional outcome and quality of life in patients with hip fracture after total knee arthroplasty

INTRODUCTION

Hip fractures are a cause of significant morbidity. While rare, ipsilateral hip fractures within 12 months after total knee arthroplasty (TKA) can negatively affect the functional outcome and the quality of life for patients who have had TKA. This aim of this study is to investigate (1) the incidence of hip fracture within 12 months after TKA and (2) the influence of hip fracture after TKA on functional outcome and quality of life in patients.

METHODS

Between March 1999 and February 2012, 25 patients who sustained an ipsilateral hip fracture within 12 months after TKA were included in this study. A propensity score matching algorithm was used to select a 1:3 control group without hip fracture. All patients were assessed using the Oxford Knee Score (OKS), Knee Society Function Score (KSFS), Knee Society Knee Score (KSKS), Physical Component Score (PCS) and Mental Component Score (MCS) of SF-36®.

RESULTS

The incidence of hip fracture was 0.16% among male patients and 0.20% for female patients. At 24 months after TKA, the OKS was 36 ± 7 in the hip fracture group versus 41 ± 5 in the control group (p = 0.003). The KSFS was 50 ± 24 in the hip fracture group versus 68 ± 21 in the control group (p = 0.001), while the KSKS was 83 ± 12 and 87 ± 8, respectively (p = 0.166). The PCS was 37 ± 12 in the hip fracture group versus 47 ± 11 in the control group (p < 0.001), while the MCS was 55 ± 10 and 54 ± 11, respectively (p = 0.664).

CONCLUSION

Although hip fracture during the rehabilitation period after TKA is uncommon, these patients have poorer functional outcome and quality of life. We recommend additional caution against hip fracture after TKA.

Recovery of knee range of motion after total knee arthroplasty in the first postoperative weeks: poor recovery can be detected early

PURPOSE

The aim of this study was to analyze in detail how knee flexion and extension progress in the first 8 weeks after primary total knee arthroplasty (TKA). The secondary goal was to compare knee range of motion (ROM) recovery patterns between patients with normal and delayed ROM recovery 8 weeks after TKA.

METHODS

This prospective clinical trial included all patients who underwent a primary unilateral TKA between February and December 2016 with weekly ROM data documented by the treating outpatient physical therapists (n = 137). Goniometry was used to measure knee ROM preoperatively, postoperatively on day 1 and weekly until follow-up at the orthopedic clinic 8 weeks after surgery. ROM recovery patterns were compared between patients with sufficient (≥ 90°) or insufficient (< 90°) knee flexion 8 weeks after TKA.

RESULTS

Knee flexion recovered from a median of 80° in the first postoperative week to 110° 8 weeks after surgery and knee extension from a mean of - 10.7° to - 3.2°. Recovery was nonlinear, with greatest improvements in the first 4 weeks for knee flexion. In contrast to patients with sufficient knee flexion 8 weeks postoperatively, the insufficient group (n = 8, 5.8%) had poor knee flexion on the first postoperative day and from week 4 to week 8 almost no improvement or even worsening of knee flexion.

CONCLUSIONS

Both knee flexion and extension recover in a nonlinear manner after TKA surgery. Poor postoperative knee function can be detected early, using ROM data from the first postoperative day up to the fourth week.

Kneeling ability after total knee replacement

Kneeling ability is consistently the poorest patient-rated outcome after total knee replacement (TKR), with 60-80% of patients reporting difficulty kneeling or an inability to kneel.Difficulty kneeling impacts on many activities and areas of life, including activities of daily living, self-care, leisure and social activities, religious activities, employment and getting up after a fall. Given the wide range of activities that involve kneeling, and the expectation that this will be improved with surgery, problems kneeling after TKR are a source of dissatisfaction and disappointment for many patients.Research has found that there is no association between range of motion and self-reported kneeling ability. More research is needed to understand if and how surgical factors contribute to difficulty kneeling after TKR.Discrepancies between patients' self-reported ability to kneel and observed ability suggests that patients can kneel but elect not to. Reasons for this are multifactorial, including knee pain/discomfort, numbness, fear of harming the prosthesis, co-morbidities and recommendations from health professionals. There is currently no evidence that there is any clinical reason why patients should not kneel on their replaced knee, and reasons for not kneeling could be addressed through education and rehabilitation.There has been little research to evaluate the provision of healthcare services and interventions for patients who find kneeling problematic after TKR. Increased clinical awareness of this poor outcome and research to inform the provision of services is needed to improve patient care and allow patients to return to this important activity. Cite this article: EFORT Open Rev 2019;4:460-467. DOI: 10.1302/2058-5241.4.180085.

The safety, efficacy and cost-effectiveness of the Maxm Skate, a lower limb rehabilitation device for use following total knee arthroplasty: study protocol for a randomised controlled trial

BACKGROUND

Physical rehabilitation is required to enhance functional outcomes and overall recovery following total knee arthroplasty (TKA). However, there are no universally accepted clinical guidelines available to consistently structure rehabilitation for TKA patients. A common method is rehabilitation provided in an outpatient setting, on a one-to-one treatment basis. This method is resource-intensive and outcomes must be compared to less costly alternatives such as home-based rehabilitation. The current study will analyse a novel home-based rehabilitation program. The Maxm skate is a portable, lower-limb, postoperative, rehabilitation exercise device for individual use in a hospital or home-based setting. This study was developed to compare the safety, efficacy and cost-effectiveness of the Maxm Skate rehabilitation program to standard rehabilitative care following TKA. The primary outcome is the range of motion (ROM) achieved by patients who received the Maxm Skate program compared to standard care at three months post TKA. Secondary outcomes include patient-reported outcomes, costs and functional evaluations which will be collected at multiple time-points up to 12 months after TKA.

METHODS

This is a single-blinded, randomised controlled trial (RCT) in which 116 eligible participants consented for primary TKA will be randomly allocated to receive either the Maxm Skate rehabilitation program or standard rehabilitative care. Fifty-eight participants per group will provide 90% power (α = 0.05) to detect 10° of difference in ROM between groups at three months after TKA, assuming a within-group standard deviation of 16° and allowing for 5% loss to follow-up. Participants randomised to the Maxm Skate group will use the skate device and accompanying iOS App and sensors to complete rehabilitation exercises, as outlined in the Maxm Skate Rehabilitation Guide. Outcomes will be compared to those receiving standard rehabilitative care. A blinded physiotherapist will evaluate functional outcomes preoperatively and at 2, 4, 6, 12, 26 and 52 weeks after TKA. The functional assessment will include measures of knee ROM, pain, isometric knee strength, balance and knee/thigh circumference. Limited measures will also be assessed at day 2 postoperatively by an alternate, unblinded physiotherapist. Clinical outcome measures will be administered preoperatively and at 6, 12 and 52 weeks postoperatively. An economic evaluation will be conducted and participants will be screened for adverse event occurrences from the time of consent to 12 months postoperatively.

DISCUSSION

This RCT will be the first to investigate the safety, efficacy and cost-effectiveness of the home-based Maxm Skate Rehabilitation program, in comparison to standard rehabilitative care following primary TKA.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry, ACTRN12616001081404p . Registered on 11 August 2016.

The Training Effect of Early Intervention with a Hybrid Assistive Limb after Total Knee Arthroplasty

After total knee arthroplasty (TKA), it is important for patients to show early improvements in knee joint function and walking to regain independence in performing the activities of daily life. We conducted for 4 weeks an intervention one week after TKA using a hybrid assistive limb (HAL: unilateral leg type) as an exoskeleton robotic device to facilitate knee joint function and walking. The intervention improved the range of knee extension movement safely and without pain compared to preoperation. In addition, we found that training with the HAL improved walking ability, speed, and rate, as well as the time taken to perform the timed up and go (TUG) test compared to preoperation. The strength of the quadriceps muscle did not improve with training; however, the patient was able to induce a knee extensor moment during the initial stance phase, as measured by kinetics and kinematics, and these actions could be performed without pain. HAL training soon after TKA improved knee joint function in a 76-year-old patient who presented with OA of the knee. The improvements in knee extension lag and knee extensor moment allowed the patient to walk without pain and regain ADL in comparison with preoperation.

Target range of motion for rehabilitation after total knee arthroplasty

Objective: Postoperative knee range of motion (ROM) is among the most important factors influencing patient satisfaction after total knee arthroplasty (TKA). The purpose of this study was to clarify the time course of improvement in knee ROM up to 12 months after TKA, including intraoperative knee ROM after implantation, and to clarify a target ROM for rehabilitation after TKA.

Patients and Methods: In total, 39 knee joints in 26 patients with osteoarthritis who underwent TKA (retaining the posterior cruciate ligament) were evaluated. Goniometry was used to measure the knee range of extension and flexion preoperatively; intraoperatively; at 1 and 2 weeks after TKA; and then at 1, 3, 6, and 12 months after TKA.

Results: The postoperative extension range gradually improved up to a maximum at 6 months after TKA; there were no significant differences in the extension range between intraoperative and 6 months after TKA, intraoperative and 12 months after TKA, or 6 and 12 months after TKA. The postoperative flexion range gradually improved, with the maximum improvement observed at 3 months after TKA; there were no significant differences in the flexion range before TKA and 3, 6, and 12 months after TKA. There were no significant differences between flexion ROM measured at 3, 6, and 12 months after TKA.

Conclusions: The changes in the knee range of extension plateaued 6 months after TKA, and those in the knee range of flexion plateaued 3 months after TKA. The target range of extension for rehabilitation from 6 months to 12 months after TKA was the intraoperative range, and the target range of flexion for rehabilitation from 3 months to 12 months after TKA was the preoperative range.

The effect of tourniquet and knee position during wound closure after total knee arthroplasty on early recovery of range of motion: a prospective, randomized study

INTRODUCTION

There is no consensus on the position of the knee joint while performing wound closure after total knee arthroplasty (TKA). Further, there are no studies focusing on the association between early functional outcomes and different wound closure strategies. Therefore, we investigated the effects of tourniquet and knee position during wound closure on early recovery of range of motion (ROM) after primary TKA. To our knowledge, this is the first study to evaluate the influence of both tourniquet and knee position during wound closure in primary TKA.

METHODS

One hundred-twenty eligible patients were consecutively enrolled in this study and randomly divided into four groups according to wound closure strategy. Wound closure was either performed with the knee in flexion at 90° or in full extension, with the combination of an inflated or deflated tourniquet. Visual analogue score (VAS), knee ROM, ROM recovery, knee society score (KSS), and wound complications were evaluated in the early postoperative period.

RESULTS

After the first postoperative week, ROM recovery in the group with knee in extension and inflated tourniquet was significantly lesser than the two groups with deflated tourniquets. Between the first and fourth postoperative weeks, ROM recovery in the group with knee inflection and deflated tourniquet was significantly higher than the two groups with knee in extension. After the first postoperative week, the visual analog score (VAS) for pain in the group with knee inflection and deflated tourniquet was significantly lesser than the two groups with inflated tourniquets. The differences in the outcomes between the four groups were not significant after the fourth postoperative week. The incidence of wound complications and KSS were not significantly different between the four groups.

CONCLUSION

Following TKA, wound closure with the knee in flexion and after deflating the tourniquet significantly decreased postoperative pain and promoted the recovery of ROM in the early postoperative period.

Knee-Extension Training with a Single-Joint Hybrid Assistive Limb during the Early Postoperative Period after Total Knee Arthroplasty in a Patient with Osteoarthritis

The knee range of motion is an important outcome of total knee arthroplasty (TKA). According to previous studies, the knee range of motion temporarily decreases for approximately 1 month after TKA due to postoperative pain and quadriceps dysfunction following surgical invasion into the knee extensor mechanism. We describe our experience with a knee-extension training program based on a single-joint hybrid assistive limb (HAL-SJ, Cyberdyne Inc., Tsukuba, Japan) during the acute recovery phase after TKA. HAL-SJ is a wearable robot suit that facilitates the voluntary control of knee joint motion. A 76-year-old man underwent HAL-SJ-based knee-extension training, which enabled him to perform knee function training during the acute phase after TKA without causing increased pain. Thus, he regained the ability to fully extend his knee postoperatively. HAL-SJ-based knee-extension training can be used as a novel post-TKA rehabilitation modality.

Capsular release around the intercondylar notch increases the extension gap in posterior-stabilized rotating-platform total knee arthroplasty

BACKGROUND

In posterior-stabilized (PS) total knee arthroplasty (TKA), various post-cam designs can be used. A larger cam of the femoral component may tighten the extension gap. Few studies have investigated the relationship between capsular release around the intercondylar notch and the extension gap. The aim of this study was to assess the effect of capsular release around the intercondylar notch on the extension gap.

METHODS

Forty-eight patients (54 knees) who underwent PS rotating-platform TKA (PFC Sigma RP-F) were enrolled retrospectively. We measured the extension gap with and without a femoral trial using a knee balancer, applying a joint distraction force of 44lb. When an intraoperative flexion contracture of >5° persisted, we performed a capsular release approximately 10mm cranial to the intercondylar notch. After full knee extension was achieved, the extension gap was measured again.

RESULTS

Thirty knees required capsular release. With a trial, the medial and lateral differences between the extension gaps before and after capsular release were 1.7mm (p<0.0001) and 2.3mm (p<0.0001), respectively. Without a trial, the gaps were enlarged by 0.4mm (p=0.0452) and 0.6mm (p=0.0215), respectively. Twenty-four knees did not require release. No significant differences were noted in the range of motion at one-year follow-up between the two cohorts.

CONCLUSIONS

With PS rotating-platform TKA, capsular release around the intercondylar notch is found to increase the extension gap and may prevent postoperative flexion contracture.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.