High-flexion Prosthesis Research Articles

Early Femoral Failure in Two Patients Undergoing Downsizing of the Femoral Component During High-Flexion Total Knee Arthroplasty

Introduction and Importance: High-flexion prostheses can be associated with a greater risk of early aseptic loosening of the femoral component than standard prosthesis.

Factors Affecting Squatting Ability in Total Knee Arthroplasty Using High Flexion Prosthesis.

PurposeTotal knee arthroplasty (TKA) is widely used as a treatment for knee osteoarthritis. Few studies have analysed the factors affecting the squatting ability of patients after TKA. The purpose of this study was to comprehensively analyse the factors affecting squatting ability after TKA and to determine which ones are important.Patients and MethodsThree hundred primary TKA cases with a minimum 3-year follow-up were retrospectively analysed. All patients received a conventional posterior-stabilized TKA implant and underwent a standard perioperative care pathway. The patients were divided into two groups according to the squatting position and knee flexion angle while weight-bearing (Group I – inability to squat group, Group II – ability to squat group). Demographic, operative, and clinical data were collected. Radiographic assessment included joint line elevation, patellar position, posterior condylar offset (PCO), etc. Statistical analysis of the effect of all the above factors on squatting ability was performed.ResultsThe preoperative range of motion and joint line of Group I were 82.9±12.6 and 3.24±1.07, respectively, and those of Group II were 107±9.6 and 1.83±0.89 respectively. The univariate analysis showed that age, prosthesis size, preoperative ROM and joint line position were correlated with squatting ability. But in the final multivariate analysis, joint line position and preoperative ROM were independent influencing factors that affected squatting ability after TKA (p value < 0.01).ConclusionPreoperative ROM and joint line position were independent influencing factors affecting squatting ability after TKA. Patients should be counseled accordingly and be made to understand these factors. To ensure that patients can squat postoperatively, we should improve surgical techniques to control joint line elevation.

Two- to Four-Year Follow-up Results of Total Knee Arthroplasty Using a New High-Flexion Prosthesis.

PurposeThe purpose of this study was to evaluate minimum 2-year follow-up results of total knee arthroplasty (TKA) performed using a new high-flexion prosthesis design (LOSPA).Materials and MethodsThe 2- to 4-year results of 191 consecutive TKAs (177 patients) with the LOSPA posterior-stabilized prosthesis were evaluated. The patients were assessed clinically and radiographically using the Knee Society scoring system (KSS) and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC).ResultsThe mean range of motion (ROM) increased significantly from 117.4° (range, 75° to 140°) preoperatively to 126.7° (range, 80° to 144°) postoperatively (p<0.001). The mean KSS and WOMAC scores improved significantly from 121.4 (range, 42 to 185) and 56.1 (range, 23 to 88) preoperatively to 174.0 (range, 130 to 200) and 16.4 (range, 0 to 85) postoperatively, respectively (both, p<0.001). One knee required revision for deep infection. No knee had aseptic loosening or osteolysis. Radiolucent lines were noted in 15 knees (7.9%).ConclusionsThe new high-flexion total knee prosthesis resulted in no early aseptic loosening of the component and improved postoperative ROM comparable to other high-flexion TKA prostheses at 2- to 4-year follow-ups.

Is High-Flexion Total Knee Arthroplasty a Valid Concept? Bilateral Comparison With Standard Total Knee Arthroplasty

BackgroundThe purpose of this study was to determine whether the high-flexion total knee prosthesis significantly improves knee flexion in vivo. MethodsForty-four patients undergoing same-day bilateral total knee arthroplasty for primary osteoarthritis of both knees were randomized to receive a standard posterior-stabilized knee prosthesis (P.F.C. Sigma; DePuy Johnson & Johnson, Warsaw, IN) in one knee and a high-flexion concept posterior-stabilized knee prosthesis (LOSPA; Corentec, Inc, Seoul, Korea) in the other knee and were followed up for 2 years postoperatively. ResultsThe mean postoperative range of motion was 128.8° (range, 100°-144°) in the LOSPA group and 128.5° (range, 100°-142°) in the P.F.C. Sigma group (P = .744). There were no significant differences in the postoperative mean Knee Society score and Western Ontario and McMaster Universities Osteoarthritis Index score between the LOSPA and P.F.C. Sigma groups (P = .839 and P = .972, respectively). ConclusionDespite theoretical range of motion advantages of high-flexion prosthesis, there were no group differences with regard to range of motion, clinical outcomes, and the incidence of radiolucent lines at final follow-up assessment.

No Superiority of High-Flexion vs Standard Total Knee Arthroplasty: An Update Meta-Analysis of Randomized Controlled Trials

This meta-analysis was performed using a Cochrane systematic review approach to examine published data with an aim to clarify whether standard or high flexion prostheses increase the range of knee motion and clinical outcomes. 1778 patients from 17 randomized controlled trials were identified. No significant differences in the range of motion, weight-bearing flexion and hip functions scores were found between treatment groups. We also found no significant differences in complications with regard to revision, component loosening, deep infection, anterior knee pain, stiffness, post-operative bone fracture and post-operative patella clunk syndrome, but the high flexion prostheses group had a higher incidence of deep venous thrombosis. The results do not support the proposition that high flexion knee prostheses provide substantial clinical advantages over standard knee prostheses.

Comparison of High-Flexion and Conventional Implants in Total Knee Arthroplasty: A Meta-Analysis

BackgroundThe purpose of this study was to evaluate whether high-flexion prostheses are superior to conventional prostheses after total knee arthroplasty (TKA).Material/MethodsWe searched the PubMed and Embase databases for randomized trials and cohort studies comparing high-flexion with conventional knee implants. The heterogeneity across studies was examined by I2 and Cochran’s Q-tests. Then the overall weighted mean differences of range of motion (ROM) and knee functional scores were evaluated.ResultsA total of 16 trials involving 2643 knees met our inclusion criteria. The results revealed that high-flexion implants were superior to conventional implants in the improvement of range of motion (weighted mean difference, 2.92; 95% CI, 1.63–4.22; p<0.0001). The clear advantage of high-flex PS (posterior stabilized) as well as high-flex CR (cruciate retaining) implants was found in ROM when compared to PS implants (2.73; 95% CI, 1.27–4.20; p=0.0003) and CR implants (3.24; 95% CI, 0.28–6.20; p=0.003), respectively. However, there was no difference in Knee Society Scores (0.42; 95% CI, −0.60–1.43; p=0.42), Knee Society function (0.37; 95% CI, −1.48–2.22; p=0.70) and Hospital for Special Surgery scores (0.26; 95% CI, −0.47–1.00; p=0.48) between high-flexion and conventional groups.ConclusionsThe current meta-analysis revealed that high-flexion implants were superior to conventional implants in the improvement of ROM but not in functional outcome scores.

Design modifications of high-flexion TKA do not improve short term clinical and radiographic outcomes.

BackgroundThe prosthesis of contemporary total knee arthroplasty (TKA) has been modified to provide a more familiar environment for higher flexion angle of the replaced knee. The design modifications continue based on evidence reported in the literature. However, whether these modifications of the prosthesis design lead to improvements in clinical results needs further investigation. We determined whether the prosthesis modifications based on recent evidence improve clinical and radiographic results following high flexion TKA.Methods524 patients who underwent primary TKA using two different high flexion prostheses were divided to Group 1 (HF-1) using a high flexion prosthesis, group 2 (HF-2) using the more recently devised high flexion prosthesis, which claims to be adopted from evidence proposed in the literature. Clinical outcomes included ranges of motion (ROM), the Knee Society knee and function score (KSKS and KSFS), the Western Ontario and McMaster Universities Arthritis Index (WOMAC) score, radiologic evaluation, and complication related to surgery.ResultsNo differences in terms of clinical and radiographic results were observed between the groups at the 2 year follow-up. The mean ROM was 123°and 124° in the HF-1 and HF-2 groups, respectively. KSKS were 90 and 89.1, KSFS were 76.6 and 81.8, and total WOMAC scores were 23.1 and 24.9 in the HF-1 and HF- 2 groups. No differences of the incidences of radiolucency on radiographs (1.4% in HF-1, 2.1% in HF-2) and dislocation (1 case in HF-1 only) was observed.ConclusionsEven if recent modifications in the design of high flexion TKA prosthesis were based on evidence in the literature, they did not provide meaningful improvements in short-term clinical and radiographic outcomes after TKA. Surgeons should consider our findings when choosing a prosthesis for their patients.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2474-15-433) contains supplementary material, which is available to authorized users.

Patients achieved greater range of movement when using high-flexion implants.

NexGen Legacy Posterior Stabilized high-flexion prostheses (LPS-Flex) have been popularized as an alternative to NexGen standard prostheses (LPS) in total knee arthroplasty (TKA). Advocates of this new generation prosthesis suggest improved postoperative knee flexion. The purpose of this study was to summarize the best evidence for comparing the range of motion (ROM) and functional outcomes of LPS-Flex prostheses and LPS in TKA. Electronic databases were systematically searched to identify relevant randomized controlled trials (RCTs). The last date for our research was July 2014. Our search strategy was followed the requirements of the Cochrane Library Handbook. The methodological quality was assessed, and the data were extracted independently by two authors. Nine studies that included 978 knees met our inclusion criteria for review. The results showed that there was larger postoperative ROM (1.62, 95% CI 0.52-2.72) in the LPS-Flex group than in the LPS group. There was not a statistically significant difference in the clinical functional scores and complications between the LPS-Flex group and the LPS group in TKA. The pooled mean differences were as follows: total KSS, -0.64 (95% CI -1.41 to 0.13); functional KSS, -0.53 (95% CI -1.51 to 0.45); HSS, 0.23 (95% CI -0.87 to 1.33); complications, 0.49 (95% CI 0.20-1.24); and radiolucent lines, 1.56 (95% CI 0.68-3.55). The preliminary results indicate that the NexGen LPS-Flex prosthesis provides an alternative to the NexGen LPS prosthesis, with greater range of motion and without severe complications or radiographic outcomes. The clinical advantages were not shown in the KSS or the HSS. Thus, the selection of a high-flexion prosthesis should depend on the characteristics of the patient, particularly high motivation and poor preoperative ROM. The potential benefits in the medium- and long-term outcomes require confirmation by larger, multicenter and well-conducted RCTs. Therapeutic study, Level I.

Clinical Outcomes in High Flexion Total Knee Arthroplasty Were Not Superior to Standard Posterior Stabilized Total Knee Arthroplasty. A Multicenter, Prospective, Randomized Study

High flexion prostheses have been introduced to achieve high flexion and improve clinical outcomes. Controversy exists in the literature regarding outcomes of high flexion vs. standard implants. This multicenter study compares outcomes in patients receiving a high flexion prosthesis vs. standard prosthesis. 278 high flexion and standard knee prostheses were used. Patients were followed for two years and evaluated prospectively. The mean HSS was 87.3 for the standard group and 88.9 for the flexion group. At two-year follow up the standard prosthesis group had mean flexion of 121° and the high flexion group had mean flexion 120°. No knee had aseptic loosening, infection, or osteolysis. At two-year follow up, there were no significant differences in range of motion, clinical outcome, or radiographic evaluation. Pre-operative motion and functional status have greater impact on clinical outcome than implant alone.

Range of Motion In High Flexion Total Knee Arthroplasty vs. Standard Posterior Stabilized Total Knee Arthroplasty A Prospective, Randomized Study

Range of motion after knee replacement is an important factor in overall outcome. The purpose was to compare motion in patients receiving high flexion prosthesis vs. standard prosthesis. 24 high flexion and standard knee prostheses were used. Patients were followed for two years and evaluated prospectively. The mean HSS was 80.4 for the standard group and 80.7 for the flexion group. At two year follow up the standard prosthesis group had mean flexion of 113°. The high flexion prosthesis group had mean flexion 106°. No knee had aseptic loosening, infection, or osteolysis. At two year follow up, there were no significant differences between groups with regard to range of motion, clinical outcome, or radiographic evaluation.Keywords: total knee arthroplasty, high flexion, range of motion

Special Considerations for TKA in Asian Patients: Editorial Comment

Despite the generally successful results of contemporary TKA, many patients remain unsatisfied with the performance of their replaced knees. This may be even more true among Asian patients, since cultural characteristics such as a floor-based lifestyle call for frequent high-flexion activities. Furthermore, if Asian patients undergoing TKA have unique demographic and anatomic features known to influence surgical outcome, these should be taken into consideration at the level of patient selection, prosthesis design, and surgical technique. Considering the rapidly increasing number of TKAs performed in Asian countries, scientific data on Asian patients undergoing TKA will prove more important in the coming years. This symposium presents 13 papers depicting unique aspects of TKAs in Asian patients. One paper focuses on the trends of TKA use in one Asian country over the past decade. This study found a fivefold increase of TKA use over the time period, which is far greater than the corresponding growth in Western countries, and the consistent dominance of female and elderly patients, which is different from less remarkable female dominance and trends toward increasing proportions of young patients observed in Western countries. Three papers from China, Japan, and Korea report the presence of unique anatomic characteristics of a patient population from their respective countries. These anatomic features can be accommodated in designing prosthesis and optimizing surgical techniques for Asian patients. Three papers from Korea report the performance of high-flexion prostheses in Korean patients and consider ethnic and cultural parameters and practical questions that deserve scrutiny in this subpopulation of Asian patients. A meta-analysis demonstrates the incidence of pulmonary embolism and deep vein thrombosis after TKA in Asians remains low, which may suggest the need for different thromboprophylactic strategies for Asian patients. Efforts to improve current prostheses or techniques would be in vain without a proper tool to evaluate outcomes. This symposium concludes with a paper proposing a new outcome measure intended to accommodate activities required for floor-based lifestyles that are rather unique for Asian cultures. It is my sincere belief and wish that the studies presented will aid clinicians caring for Asian patients undergoing TKA. I would like to thank all authors for contributing their excellent work to this symposium and all the reviewers for their thoughts and suggestions on the manuscripts. I would also like to extend my sincerest gratitude to Richard A. Brand MD, the former editor- in-chief of CORR®, and Edward G. McFarland MD, the president of the Association of Bone and Joint Surgeons®, for inspiring me to propose this symposium and for supporting our Asian colleagues who contributed to this symposium (Fig. 1). Fig. 1 Dr. Tae Kyun Kim is shown.

Factors affecting range of motion in total knee arthroplasty using high flexion prosthesis: A prospective study

Background:High flexion implants have been reported to provide better range of motion (ROM). The few studies analyzing the factors affecting the ROM are scarce. This study aims to find the factors that affect ROM when using a high flex knee design (INDUS knee).Materials and Methods:Two hundred and fifty three consecutive patients of total knee arthroplasty (TKA) done by using INDUS knee prosthesis between Sept 2008 and Sept 2009 were included in the study. The cases with osteoarthritis (OA) and Rheumatoid arthritis (RA) were included in study. 5 patients were lost to followup and 248 patients (267 knees, 19 bilateral, 221 OA, and 46 RA) were analyzed for the following factors – sex, age, body mass index (BMI), preoperative ROM, flexion deformity, preoperative total knee score and functional score, time of tourniquet release and patella resurfacing. Subgroup classification using above factors was performed and statistical analysis of effect of all the above factors on final knee ROM was done. Assessment was done preoperatively and at 3 months, 6 months and 1 year postoperatively. The final outcome evaluation was done at one year followup.Results:The mean age was 68.2 years (range 40-89 years) with 79 males and 189 females. The mean knee range improved from 97.62 ± 11° to 132 ± 8°. Factors that positively affect ROM of INDUS knee prosthesis at the end of 1 year were preoperative ROM, total knee score and functional score, and diagnosis of osteoarthritis, whereas BMI, preoperative flexion deformity has a negative influence on final flexion at the end of 1 year. Age and gender of the patients, patella resurfacing, and use of two different tourniquet protocols did not affect the final outcome.Conclusion:Preoperative ROM and preoperative functional status are the most important factors affecting final range. Patients should be counseled accordingly and made to understand these factors.

A Sex-Specific Prosthesis Was Not Superior to a High-Flexion Prosthesis in Women Having Total Knee Replacement

A Sex-Specific Prosthesis Was Not Superior to a High-Flexion Prosthesis in Women Having Total Knee Replacement

High-flexion Prosthesis Improves Function of TKA in Asian Patients Without Decreasing Early Survivorship

Two previous studies recently raised the possibility of a high risk of early femoral components loosening with high-flexion (HF) prostheses in Asian populations and suggested that the high failure rate of HF TKAs was associated with HF ability. However, these findings are controversial given other studies reporting a low incidence of aseptic failures in HF prostheses. We therefore determined (1) the rate of achieving postoperative HF after HF TKA; (2) whether the aseptic loosening rate of HF prostheses is high; and (3) whether the survivorship was worsened in patients who achieved postoperative deep knee flexion in our cohort of Korean patients. We retrospectively reviewed 488 patients who had 698 primary TKAs using the NexGen(®) Legacy Posterior-Stabilized Flex system implanted from 2003 to 2010. There were 40 men and 448 women with a mean age of 68 years. We obtained Hospital for Special Surgery scores, maximal flexion, and radiographs. The minimum followup for functional and radiographic evaluations was 2 years (median, 4.8 years; range, 2-8.7 years). We performed a survival analysis on all patients for aseptic loosening. Three hundred sixty knees (52%) could achieve ≥ 135° maximum flexion. Six of the 698 knees (0.9%) developed aseptic loosening (three femoral and three tibial). The survival at 5 years for aseptic loosening was 99.1%. The overall survival for aseptic failure did not differ between knees that achieved HF and those that did not. We observed a low incidence of early aseptic loosening of HF designs in this series. Our findings suggest HF TKAs have high survival in Asian patients at 5 years although half of the patients attained maximum flexion more than 135° postoperatively.

High Early Failure Rate of the Columbus® Posterior Stabilized High-flexion Knee Prosthesis

Most studies report high survivorship rates for TKAs, however, we observed higher than anticipated rates of dislocation and femoral component loosening after implanting a Columbus posterior stabilized prosthesis. We therefore determined (1) the incidence of dislocation and aseptic loosening that occurred after implantation of posterior stabilized high-flexion prostheses in TKAs, (2) the causative factors of dislocation and aseptic femoral component loosening when comparing two designs of prostheses, and (3) the mechanisms of dislocation. We retrospectively reviewed 319 patients who underwent 384 TKAs from May 2007 to July 2008. These patients had been assigned alternately to receive a Scorpio posterior stabilized knee prosthesis (Group I, 158 patients, 187 knees) or a Columbus posterior stabilized knee prosthesis (Group II, 161 patients, 197 knees). We followed the patients with clinical and radiographic evaluations for a minimum of 24 months (mean, 26 months; range, 24-38 months). Ten retrieved prostheses were examined visually. Ten dislocations (5.1%; 10 of 197 knees) and seven aseptic loosenings of femoral components (3.6%; seven of 197 knees) occurred in Group II at a mean of 10.9 months postoperatively. However, no dislocation or loosening occurred in patients in Group I. Most dislocations were associated with varus flexion or flexion rotation movements during normal daily activities. The cam jump distance at 90º flexion for the Columbus prosthesis was lower than for the Scorpio prosthesis. We observed a high rate of early failure during short-term followup after implantation of a Columbus posterior stabilized prosthesis. It appears that early failures of the Columbus design were related to a different cam-post design attributable to a low jump distance during knee flexion. We no longer recommend using this device. Level II, prognostic study. See the Guidelines for Authors for a complete description of levels of evidence.

High-Flexion versus Conventional Total Knee Arthroplasty: A 5-Year Study

To compare mid-term outcomes of a high-flexion prosthesis with a conventional prosthesis. Records of 107 consecutive patients who underwent total knee arthroplasty (TKA) for primary osteoarthritis by a single surgeon were reviewed. 21 men and 36 women (mean age, 65 years) used a high-flexion prosthesis (NexGen CR-Flex Mobile, Zimmer), whereas 38 men and 12 women (mean age, 67 years) used a conventional prosthesis (Genesis II, Smith & Nephew) that preserves the posterior cruciate ligament, with mobile-bearing polyethylene inlay. The Knee Society knee and functional scores and the range of motion (especially maximum passive flexion) were assessed. Radiographs were evaluated to identify radiolucent lines at the bone cement interface, patella tracking, tibiofemoral alignment, and implant positioning. The mean follow-up period was 68 (range, 51- 70) months. In terms of the mean Knee Society scores and range of motion, the difference between groups was not significant (p>0.05), but the improvement in both groups after TKA was significant (p<0.005). Respectively in the high-flexion and conventional TKA groups, 2 and one of the patients developed deep vein thrombosis and were treated with anticoagulants for 3 months. One and 5 of the patients had an unsatisfactory range of motion (<60º) in week 1, which was resolved with mobilisation under general anaesthesia in combination with a peridural catheter for analgesia. No patient developed implant-specific complications such as aseptic loosening (osteolysis, progressive radiolucent lines, implant deviation) or dislocation of the polyethylene insert. The high-flexion prosthesis revealed no significant advantages over the conventional prosthesis in terms of the Knee Society scores and range of motion. Long-term studies are needed to determine whether the high-flexion implant is superior to the conventional implant in terms of polyethylene wear and aseptic loosening.

Design of high-flexion total knee prosthesis considering activities of North African peoples

Design of high-flexion total knee prosthesis considering activities of North African peoples

High-Flexion vs Conventional Prostheses Total Knee Arthroplasty: A Meta-Analysis

Whether high-flexion prostheses are superior to conventional prostheses after total knee arthroplasty (TKA) remains controversial. Therefore, this meta-analysis was conducted to evaluate the effects of these 2 different designs. After a comprehensive search, 11 trials with 1204 knees were eligible for data extraction and pooled analysis. The results demonstrated that there were no differences in range of motion of high-flexion posterior-stabilized vs standard posterior-stabilized TKA (weighted mean improvement, 0.93°; 95% confidence intervals, −0.75° to 2.60°; P = .28), range of motion of high-flexion cruciate-retaining vs cruciate-retaining TKA (2.06°; 0.06°-4.17°; P = .06), weight-bearing flexion (2.05°; 0.99°-5.08°; P = .19), Knee Society Scores (1.59 points; 0.42-3.60 points; P = .12), and Hospital for Special Surgery Scores (0.84 points; 0.37-2.04 points; P = .17) with at least 1-year follow-up. No infection, loosening, and osteolysis were found. The current evidences cannot confirm that high-flexion prostheses are superior to conventional prostheses.

High-flexion total knee arthroplasty improves flexion of stiff knees

High-flexion knee prosthesis designs are generally thought to be of benefit only in patients with a satisfactory preoperative flexion angle. The aim of the study was to evaluate whether high-flexion designs were indeed worthless in osteoarthritis patients with severe preoperative flexion limitation. The postoperative maximum flexion was compared in osteoarthritis patients with a preoperative maximum flexion of 100° or less, using LPS and LPS-flex implants (NexGen®; Zimmer, Warsaw, IN) in total knee arthroplasties. Data on 39 knees in the LPS group and 41 in the LPS-flex group, with a minimum of 2 years of follow-up, were reviewed retrospectively, focused on the postoperative maximum flexion. Two years after operation, the LPS-flex group had a mean postoperative maximum flexion of 131±10° (range, 105-140°), which was significantly higher than the 121±12° (range, 95-140°) in the LPS group (P<0.001). In the LPS-flex group, about half of the knees (n=18, 44%) could achieve a maximum flexion of 140° postoperatively, but in the LPS group only five knees (13%) achieved a maximum flexion of 140°. Despite a different period of the operation between groups, this study suggested that osteoarthritis patients with severe preoperative flexion limitation could achieve more postoperative gain in flexion when a high-flexion prosthesis was used, compared to the flexion obtained using a standard prosthesis.

High-Flexion Total Knee Replacement: Functional Outcome at One Year

Implants designed for enhanced flexion offer the prospect of improved function after total knee replacement (TKR). Whereas most studies evaluating these implants have focused on the range of knee flexion achieved, this study investigated the quality of function in deep knee flexion. The influences of residual pain and maximum flexion angle on function in deep knee flexion were also examined. Eighty-three patients (100 knees) were prospectively followed for 1year after TKR with a rotating-platform posterior-stabilized high-flexion prosthesis. Range of motion was measured and Knee Society scores were calculated. A questionnaire evaluated residual knee pain and function in high-flexion activities. Mean Knee Society score was 95, and mean knee flexion was 125°, yet 20% of patients could neither kneel, nor squat, nor sit on their heels. Fifty-seven percent were able to kneel without significant difficulty; 69% were able to squat without significant difficulty; and 46% were able to sit on their heels without significant difficulty. Function in deep flexion correlated with pain scores but did not correlate with knee flexion angles or Knee Society scores. Results 1year after TKR with a rotating-platform posterior-stabilized high-flexion prosthesis are encouraging, but one in five patients remain significantly limited in high-flexion activities.