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Background: Accelerometer-based navigation is a handheld navigation tool that was introduced to offer a simpler technique compared with more-cumbersome computer-assisted surgery (CAS). Considering the increasing number of adopters, it seems important to evaluate the potential clinical benefits of this technology compared with conventional TKA., Questions/purposes: In this systematic review, we asked: (1) Is accelerometer-based navigation more accurate than conventional TKA? (2) Does accelerometer-based navigation provide better functional outcome than conventional TKA? (3) Does accelerometer-based navigation increase surgical time or decrease the risk of complications or reoperations compared with conventional TKA?, Methods: This systematic review included all comparative prospective and retrospective studies published in the MEDLINE/PubMed and Cochrane libraries over the last 10 years. Inclusion criteria were all studies in English that compared accelerometer-based navigation with conventional TKA. Eleven studies met these criteria with 621 knees in accelerometer-based navigation group and 677 knees in conventional TKA group. Results related to alignment, objective and subjective functional scores, duration of surgery, complications and reoperations were extracted and compared between accelerometer-based-navigation and conventional TKA. Methodological quality was assessed using Methodological Index for Non-Randomized Studies (MINORS) tool (for nonrandomized control trials) and Cochrane Risk of Bias (for randomized control trials (RCTs). All studies with fair or better quality were included. Four RCTs and six nonrandomized studies comparing accelerometer-based navigation to conventional TKA were found., Results: Inconsistent evidence on mechanical axis alignment was found, with five of nine studies slightly favoring the accelerometer-based navigation group, and the other four showing no differences between the groups. Only two of eight studies favored accelerometer-based navigation in terms of tibial component alignment in the coronal plane; the other six found no between-group differences. Similarly, mixed results were found regarding other metrics related to component alignment; a minority of studies favored accelerometer-based navigation by a small margin, and most studies found no between-group differences. Only three studies evaluated functional outcome and none of them showed a difference in range of motion or patient-reported outcomes. Most studies, six of seven, found no between-group differences concerning surgical time; one study demonstrated a slight increase in time with accelerometer-based navigation. There were no between-group differences in terms of the risk of complications, which generally were uncommon in both groups, and no reoperations or revisions were reported in either group., Conclusions: We found conflicting evidence about whether accelerometer-based navigation reduces the number of coronal-plane outliers or improves alignment to a clinically important degree, and we found no evidence that it improves patient-reported outcomes or reduces the risk of complications or reoperations. Accelerometer-based navigation may increase surgical time. The overall quality of the evidence was low, which suggested that any observed benefits were overestimated. Given the absence of higher-quality evidence demonstrating compelling benefits of this accelerometer-based navigation technology, it should not be widely adopted., Level of Evidence: Level III, therapeutic study.

Background: Previously published studies reported benefits of computer-assisted surgery (CAS) in terms of radiographic implant position in TKA, but whether these improvements result in clinically important survival differences or functional differences that a patient might perceive at a minimum 10-year followup remains largely unknown., Questions/purposes: We performed a prospective randomized trial and asked whether CAS (1) improved survival free from aseptic loosening; and (2) demonstrated any clear difference in patient-reported outcomes at latest followup using validated outcome measures at minimum 10-year followup., Methods: Between January 2004 and December 2005, 80 patients scheduled for TKA were randomly assigned either to the CAS group or to the conventional technique group by the Hospital Informatics Department. The patient inclusion criteria were age 20 to 80 years old, weight < 100 kg, and consent to receive a primary knee arthroplasty performed through a medial parapatellar approach by the senior author. The exclusion criteria were a history of prior knee surgery, TKA performed for a posttraumatic indication, or revision knee surgery. The first 80 patients meeting these criteria were included in the study. There were 21 women and 19 men and in each group; mean age was 66 years (range, 58-77 years), and mean body mass index was 27 ± 4 kg/m. An initial published study using this patient group investigated only differences regarding implant positioning in the coronal and sagittal planes. This is a secondary analysis of patients from the earlier study protocol at a minimum of 10-year followup with different endpoints. Kaplan-Meier survivorship was compared between groups, and functional patient-reported outcome measures (PROMs) were evaluated using the SF-12, Knee Injury and Osteoarthritis Outcome Score (KOOS), Forgotten Joint Score, and the new Knee Society Score. Those PROMs were not available at the time of the original randomized controlled trial and we therefore do not have baseline preoperative values demonstrating that our two groups were comparable. However, our groups were created using strict randomization and were similar in terms of demographic parameters and knee deformities. Our secondary analysis was not powered for survival analysis but had 80% power to detect a difference > 6 points on the SF-12 components and > 6 points out of 100 on the KOOS subscores (published minimal clinically important difference: 8 points) at the p < 0.05 level., Results: With the numbers available, there was no difference between the CAS group and the conventional TKA group in terms of survivorship free from aseptic loosening 10 years after TKA (97%, 95% confidence interval [CI], 95%-99% versus 97%, 95% CI, 95%-99%; p = 0.98). Investigation of the latest followup PROM scores showed no difference between SF-12 scores (respectively, for CAS and control patients, physical SF-12: 72 ± 12 versus 73 ± 13 mean difference 0, 95% CI -3 to 3, p = 0.9; mental SF-12: 75 ± 8 versus 73 ± 10, mean difference 2, 95% CI 0-4, p = 0.3) as well as for all KOOS subscores (all p > 0.1). Forgotten Joint Scores were similar in both groups with 83 ± 4 for CAS and 82 ± 5 for control patients (mean difference 1, 95% CI 0-2, p = 0.2). Finally, the new Knee Society Scores were not statistically different between groups with a mean objective score of 82 ± 13 for CAS patients versus 79 ± 12 for control patients (mean difference 2, 95% CI 0-5, p = 0.5) and a mean subjective score of 83 ± 11 versus 85 ± 12, respectively (mean difference 2, 95% CI 0-5, p = 0.5)., Conclusions: Our observations suggest that CAS used for TKA alignment with restoration of a neutral mechanical axis as the goal did not confer any substantial advantage in survivorship, function, or quality of life at 10 years after TKA. Larger studies with longitudinal collection of PROMs for functional assessment and greater numbers to assess survivorship are needed to confirm these findings., Level of Evidence: Level III, therapeutic study.

Background: Recent clinical studies have reported that patients with higher body mass index (BMI) are more likely to experience premature failure of total knee arthroplasty (TKA), lower knee scores, and perhaps more pain in the prosthetic joint. However, it is not known whether certain implant design features such as tibial stems might be associated with differences in the frequency of tibial pain in patients with higher BMIs., Questions/purposes: Therefore, it was our aim to compare (1) function and pain (as measured by the New Knee Society Score, Knee Injury and Osteoarthritis Outcome Score [KOOS], and visual analog pain scores); (2) quality of life (as measured by SF-12); and (3) mechanical complications and premature revision (defined as revision before 2 years) between patients with obesity undergoing TKA (BMI > 30 kg/m 2 ) who received either a stemmed or an unstemmed tibial component., Methods: In this randomized controlled trial, 120 patients with a BMI > 30 kg/m 2 scheduled for primary arthritis TKAs and end-stage knee osteoarthritis were included. Patients were stratified into groups defined as moderately obese (BMI 30-35 kg/m 2 , N = 60) and severely obese (BMI > 35 kg/m 2 , N = 60) groups. Patients in each stratified subgroup then were randomized to receive either a stemmed (10 mm/100 mm) proximally cemented tibial component or the other, a standard cemented component. Patients were evaluated preoperatively and 2 years after surgery using the new Knee Society Score (KSS), KOOS, SF-12 score, and a visual analog pain score after 100 meters of walking. Although no minimum clinically important differences (MCIDs) have yet been defined for the new KSS, we considered differences smaller than 10 points to be unlikely to be clinically important; the MCID for the KOOS is estimated at 8 to 10 points, the SF-12 to be 4 points, and the visual analog scale to be 2 cm on a 10-cm scale. Patients were followed until death, revision, or for a minimum of 2 years (mean, 3 ± 0.8 years; range, 2-4 years). No patient was lost to followup before 2 years., Results: Although we found that patients treated with stemmed TKAs had higher functional outcomes, the differences were small and unlikely to be clinically important (subjective KSS mean 69 ± 7 points versus 75 ± 7, mean difference 6 points, 95% confidence interval [CI] 2-11, p = 0.03; objective KSS mean 80 ± 6 points versus 85 ± 6 points, mean difference 5 points, 95% CI 0-9, p = 0.01). Compared with patients with a stemmed TKA, patients with a standard implant reported lower KOOS pain subscores (81 ± 9 versus 76 ± 8; p = 0.04) and lower KOOS symptom subscores (74 ± 7 versus 68 ± 7; p = 0.03). The proportions of patients experiencing complications were not different with the numbers available for all groups and subgroups., Conclusions: Although we detected differences in some patient-reported outcomes scores for pain and function favoring implants with stems, the differences were small and unlikely to be clinically important. Because these stems may have disadvantages, perhaps including difficulty of revision, we cannot draw a strong conclusion in support of their use., Level of Evidence: Level I, therapeutic study.

Background: Computer-assisted surgery (CAS) for cup placement has been developed to improve the functional results and to reduce the dislocation rate and wear after total hip arthroplasty (THA). Previously published studies demonstrated radiographic benefits of CAS in terms of implant position, but whether these improvements result in clinically important differences that patients might perceive remains largely unknown., Questions/purposes: We hypothesized that THA performed with CAS would improve 10-year patient-reported outcomes measured by validated scoring tools, reduce acetabular polyethylene wear as measured using a validated radiological method, and increase survivorship., Methods: Sixty patients operated on for a THA between April 2004 and April 2005 were randomized into two groups using either the CAS technique or a conventional technique for cup placement. All patient candidates for a THA with the diagnosis of primary arthritis or avascular necrosis were eligible for the CAS procedure and randomly assigned to the CAS group by the Hospital Informatics Department with use of a systematic sampling method. The patients assigned to the freehand cup placement group were matched for sex, age within 5 years, pathological condition, operatively treated side, and body mass index within 3 points. All patients were operated on through an anterolateral approach (patient in the supine position) using cementless implants. In the CAS group, a specific surgical procedure using an imageless cup positioning computer-based navigation system was performed. There were 16 men and 14 women in each group; mean age was 62 years (range, 24-80 years), and mean body mass index was 25 ± 3 kg/m(2). No patient was lost to followup at 10 years, but five patients have died (two in the CAS group and three in the control group). At the 10-year followup, an independent observer blinded to the type of technique performed patients' evaluation. Cup positioning was evaluated postoperatively using a CT scan in the two groups with results previously published. At 10 years, we assessed subjective functional outcome and quality of life using validated questionnaires (SF-12, Harris hip score [HHS], Hip injury and Osteoarthritis Outcome Score). Wear rate was then evaluated on standardized radiographs using a previously validated semiautomated computer analogic measurement method (dual circle method). Complications and survivorship were compared between groups. With our available sample size, this study had 80% power to detect a difference of 4 points out of 100 on the HHS at the p < 0.05 level., Results: With the numbers available, we found we found no differences between groups regarding HSS at last followup 95.3 ± 5.9 points (CAS group) versus 96.2 ± 4.5 points, a mean difference of 0.9 points (95% confidence interval [CI], -4.3 to 4.6; p = 0.6). There was no difference between the groups in terms of the mean (± SD) acetabular linear wear at 10 years. The mean wear was 0.71 ± 0.6 mm in the CAS group versus 0.77 ± 0.52 mm in the control group, a mean difference of 0.06 mm (95% CI, -0.1 to 0.2; p = 0.54). With the numbers available, there was no difference between the CAS group and the conventional THA groups in terms of survivorship free from aseptic loosening (100%; 95% CI, 100%-95%, versus 100%; 95% CI, 100%-94%; p = 0.3)., Conclusions: Our observations suggest that CAS used for cup placement does not confer any substantial advantage in function, wear rate, or survivorship at 10 years after THA. Because CAS is associated with added costs and surgical time, future studies need to identify what clinically relevant advantages it offers, if any, to justify its continued use in THA., Level of Evidence: Level II, therapeutic study.

Background: Component alignment can influence implant longevity as well as perhaps pain and function after unicompartmental knee arthroplasty (UKA), but correct alignment is not consistently achieved. To increase the likelihood that good alignment will be achieved during surgery, smart tools such as robotics or patient-specific instrumentation (PSI) have been introduced., Questions/purposes: We hypothesized that UKA performed with PSI would result in improved level gait as ascertained with three-dimensional analysis, implant positioning, and patient-reported outcomes measured by a validated scoring system when compared with conventional instrumentation 3 months and 1 year after surgery., Methods: We randomized 60 patients into two groups using either the PSI technique or a conventional technique. All patients were operated on using the same technique and the same cemented metal-backed implant. Mean age of the patients was 63 ± 4 years (range, 54-72 years) and mean body mass index was 28 ± 3 kg/m(2). Patients were evaluated preoperatively, at 3 months, and 1 year after surgery by an independent observer blind to the type of technique. Gait parameters were assessed with three-dimensional analysis during level walking preoperatively and at 1 year, frontal and sagittal position of the implant was evaluated on full-length radiographs at 3 months, and subjective functional outcome and quality of life using routine questionnaires (SF-12, new Knee Society Score [KSS], Knee Injury and Osteoarthritis Outcome Score) at 3 months and 1 year. This study had 80% power to detect a 15% difference in walking speed at the p < 0.05 level., Results: One year after surgery, there were no differences between the two groups in the analyzed gait spatiotemporal parameters, respectively, for PSI UKA and conventional UKA : double limb support 31% (25%-54%) versus 30% (23%-56%; p = 0.67) and walking speed (1.59 m/s [0.86-1.87 m/s] versus 1.57 m/s [0.71-1.96 m/s]; p = 0.41). No difference was observed between the two groups in terms of lower limb alignment (PSI group 178° ± 3°, conventional group 178° ± 4°; p = 0.24) or implant positioning on mediolateral and anteroposterior radiographs. There were no differences in the functional score between the PSI and conventional TKA groups at 3 months and 1 year after surgery: KSS objective knee scores (PSI: 85 ± 8 points at 3 months, 87 ± 5 points at 1 year and conventional instrumentation: 82 ± 8 points at 3 months 83 ± 6 points at 1 year; p = 0.10) and functional activity scores were similar in both group (PSI: 71 ± 12 points at 3 months and 74 ± 7 points at 1 year versus conventional group: 73 ± 11 points at 3 months and 75 ± 6 at 1 year; p = 0.9)., Conclusions: Our observations suggest that PSI may confer small, if any, advantage in alignment, pain, or function after UKA. This argument can therefore not be used to justify the extra cost and uncertainty related to this technique., Level of Evidence: Level I, therapeutic study.

Background: Patellofemoral arthroplasty (PFA) can be considered in patients with patellofemoral disease. However, the use of partial arthroplasty often causes concern among clinicians and patients that revision to total knee arthroplasty (TKA) will be needed and, if so, whether this revision will be straightforward or more complicated., Questions/purposes: We set out to determine if conversion of a PFA to a TKA was more similar to a primary or to a revision TKA in terms of surgical characteristics, knee scores, range of motion, and complications., Methods: Between 2001 and 2008, we revised 21 PFAs to TKAs, all of which were available for followup at a minimum of 5 years (median, 6 years; range, 5-12 years). These patients were matched one-to-one by age, sex, body mass index, length of followup, and preoperative Knee Society Scores (KSS) to 21 primary and 21 revision TKAs. We analyzed operative time and amount of blood loss. Clinical outcomes assessed were range of motion and KSS., Results: Blood loss (405 mL versus 460 mL versus 900 mL; odds/hazard ratio, 1.33, 95% confidence interval [CI], 0.3-5.85; p=0.14 for primary TKA versus revision PFA and odds/hazard ratio, 0.13, 95% CI, 0.03-0.52; p<0.01 for revision PFA versus revision TKA) and operative time (52 minutes versus 72 minutes versus 115 minutes; odds/hazard ratio, 5.45, 95% CI, 1.23-27.4; p=0.02 for primary TKA versus revision PFA and odds/hazard ratio, 0.5, 95% CI, 0.01-0.44; p<0.001 for revision PFA versus revision TKA) were not different between the primary TKA and revision PFA groups but higher in the revision TKA group. KSS (knee and function) were higher in the primary TKA group (92 [range, 60-100] and 91 [range, 65-100]) than they were in the revision PFA (85 [range, 40-100] and 85 [range, 30-100]) and revision TKA groups (75 [range, 30-100] and 68 [range, 25-100]; p<0.001). Flexion was better in the primary TKA (125 [range, 105-130]) and revised PFA (120 [range, 100-130]) groups than the revision TKA group (105 [range, 80-115]; p=0.0013). There were more complications in the revision PFA group (two of 21) compared with the primary TKA group (zero of 21, p=0.005) but not compared with the revision TKA group (three of 21; p=0.85)., Conclusions: With the numbers available, we found that revising a PFA is comparable to a primary TKA in regard to surgical characteristics and postoperative clinical outcomes (including knee scores and range of motion), and both are superior to revision TKA, although the frequency of complications was higher in the revision PFA group than it was in the primary TKA group. The majority of patients undergoing revision of a PFA to a TKA can be treated with a standard implant., Level of Evidence: Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Background: Although some clinical reports suggest patient-specific instrumentation in TKA may improve alignment, reduce surgical time, and lower hospital costs, it is unknown whether it improves pain- and function-related outcomes and gait., Questions/purposes: We hypothesized that TKA performed with patient-specific instrumentation would improve patient-reported outcomes measured by validated scoring tools and level gait as ascertained with three-dimensional (3-D) analysis compared with conventional instrumentation 3 months after surgery., Methods: We randomized 40 patients into two groups using either patient-specific instrumentation or conventional instrumentation. Patients were evaluated preoperatively and 3 months after surgery. Assessment tools included subjective functional outcome and quality-of-life (QOL) scores using validated questionnaires (New Knee Society Score(©) [KSS], Knee Injury and Osteoarthritis Outcome Score [KOOS], and SF-12). In addition, gait analysis was evaluated with a 3-D system during level walking. The study was powered a priori at 90% to detect a difference in walking speed of 0.1 m/second, which was considered a clinically important difference, and in a post hoc analysis at 80% to detect a difference of 10 points in KSS., Results: There were improvements from preoperatively to 3 months postoperatively in functional scores, QOL, and knee kinematic and kinetic gait parameters during level walking. However, there was no difference between the patient-specific instrumentation and conventional instrumentation groups in KSS, KOOS, SF-12, or 3-D gait parameters., Conclusions: Our observations suggest that patient-specific instrumentation does not confer a substantial advantage in early functional or gait outcomes after TKA. It is possible that differences may emerge, and this study does not allow one to predict any additional variances in the intermediate followup period from 6 months to 1 year postoperatively. However, the goals of the study were to investigate the recovery period as early pain and functional outcomes are becoming increasingly important to patients and surgeons., Level of Evidence: Level I, therapeutic study. See the Instructions to Authors for a complete description of levels of evidence.

Background: While some clinical reports suggest minimally invasive surgical (MIS) techniques improve recovery and reduce pain in the first months after TKA, it is unclear whether it improves gait and thigh muscle strength., Questions/purposes: We hypothesized TKA performed through a mini-subvastus approach would improve subjective and objective and subjective function compared to a standard medial parapatellar approach 2 months after surgery., Methods: We randomized 40 patients into two groups using either the mini-subvastus approach or standard medial parapatellar approach. Patients were evaluated preoperatively and 2 months after surgery. We assessed subjective functional outcome and quality of life (QOL) using routine questionnaires (SF-12, Knee Society Score [KSS], Knee Injury and Osteoarthritis Outcome Score [KOOS], UCLA activity, patient milestone diary of activities). We determined isometric strength of the thigh muscles and assessed gait with a three-dimensional (3-D) analysis during level walking and stair climbing., Results: We observed improvements from preoperatively to 2 months postoperatively in functional scores, QOL, and knee kinematic and kinetic gait parameters during level and stair walking. Isometric quadriceps strength increased in both groups, although remaining lower when compared to sound limbs. We found no differences between the groups in KSS, SF-12, KOOS, UCLA activity, patient milestone diary of activities, isometric quadriceps strength, or 3-D gait parameters, except a marginally higher speed of stair ascent in the MIS group., Conclusions: Our observations suggest an MIS approach does not confer a substantial advantage in early function after TKA., Level of Evidence: Level I, therapeutic study. See Instructions to Authors for a complete description of levels of evidence.

Background: Return to sport is a key patient demand after hip arthroplasty and some patients are even involved in high-impact sports. Although polyethylene wear is related to the number of cycles and the importance of the load, it is unclear whether high-impact sport per se influences THA durability., Questions/purposes: Therefore, we compared (1) function between the patients involved in high-impact sports and the patients with lower activities as measured by the Harris hip score (HHS) and the Hip Osteoarthritis Outcome Score (HOOS); (2) linear wear rates; and (3) survivorships considering revision for mechanical failure with radiographic signs of aseptic loosening as the end point., Methods: We retrospectively identified 70 patients who engaged in high-impact sports and 140 with low activity levels from among 843 THAs from a prospectively collected database performed between September 1, 1995, and December 31, 2000. Patients were evaluated at a minimum followup of 10 years (mean, 11 years; range, 10-15 years) by two independent observers. We obtained a HHS and HOOS at each followup., Results: The mean HOOS was higher in the high-impact group for three of the five subscales of the HOOS. Mean linear wear was higher in the high-impact group than in the low-activities group. We also found a higher number of revisions in the high-activity group., Conclusions: Our observations confirm concern about the risk of THA mechanical failures related to high-impact sport, and patient and surgeons alike should be aware of these risks of mechanical failures., Level of Evidence: Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Background: Early studies in the literature reported relatively high early minor reintervention rate for the mobile-bearing unilateral knee arthroplasty (UKA) compared with short- and midterm survivorship after fixed- or mobile-bearing UKA. However, whether the long-term function and survivorship are similar is unclear., Questions/purposes: We therefore asked whether (1) mobile- or fixed-bearing UKAs have comparable function (as measured by the Knee Society scores); (2) mobile- and fixed-bearing UKA have comparable Knee Society radiographic scores; and (3) the long-term survivorship is comparable., Methods: We retrospectively reviewed 75 patients (79 knees) with a fixed-bearing UKA and 72 patients (77 knees) with a mobile-bearing UKA operated on between 1989 and 1992. Mean age of the patients was 63 years; gender and body mass index (26 kg/m(2)) were comparable in the two groups. We obtained Knee Society function and radiographic scores and determined survival. The minimum followup was 15 years (mean, 17.2 ± 4.8 years; range, 15-21.2 years)., Results: The mean Knee Society function and knee scores were comparable in the two groups. Radiographically, the number of overcorrections and the number of radiolucencies were statistically higher in the mobile-bearing group (69% versus 24%). At final followup, considering revision for any reason, 12 of 77 (15%) UKAs were revised (for aseptic loosening, dislocation, and arthritis progression) in the mobile-bearing group and 10 of 79 (12%) in the fixed-bearing group (for wear and arthritis progression)., Conclusions: This long-term study did not demonstrate any difference in survivorship between fixed and mobile-bearing but pointed out specific modes of failure.

Background: Posttraumatic arthritis secondary to lateral tibial plateau fracture malunion causes pain and limited function for patients. It is sometimes technically challenging to correct malalignment in these patients with advanced arthritis using osteotomies. Lateral unicompartmental knee arthroplasty (UKA) may be an option to treat such patients., Questions/purposes: We asked whether UKA for lateral posttraumatic osteoarthritis (1) reliably alleviates pain and improve function, (2) restores lower limb alignment, and (3) is as durable as UKA for primary lateral osteoarthritis., Patients and Methods: We retrospectively reviewed 13 patients with lateral cemented UKA (mean age at surgery, 50.1 years) treated at two institutions between 1985 and 2007. We obtained Knee Society scores and evaluated radiographs for evidence of implant loosening or progression of arthritis in the medial compartment. Minimum followup was 3 years (mean, 10.2 years; range, 3-22.1 years)., Results: Mean Knee Society knee score improved from 51 points (range, 29-75 points) preoperatively to 88 points (range, 65-100 points) at last followup, suggesting the procedure relieved pain. Mean function score improved from 51 points (range, 10-89 points) preoperatively to 87 points (range, 35-100 points) at last followup. The mean hip-knee-ankle angle was 188° preoperatively (range, 184°-193º) and 185° (range, 183°-188°) at last followup. Prosthesis survivorship was 100% at 5 and 10 years and 80% at 15 years., Conclusions: Despite the limited number of indications and technical considerations, our observations suggest lateral UKA is a reasonable option for treating lateral arthritis secondary to malunited fractures.

Unlabelled: THA in young patients is challenging regarding restoration and survival because patients are young, active, and tend to have disturbed anatomy. We asked whether a three-dimensional custom cementless stem could restore hip function, decrease osteolysis and wear, and enhance stem survival in young patients. We retrospectively reviewed 212 patients (233 hips) younger than 50 years (mean, 40 years) at a followup of 5 to 16 years (mean, 10 years). The Merle D'Aubigné-Postel and Harris hip scores improved at last followup. No thigh pain was recorded for any of the patients; 187 of the 212 patients (88%) had full activity recovery, 206 had full range of motion, and 151 had a score greater than 80 points for all five categories of the Hip disability and Osteoarthritis Outcome score. Five patients had femoral osteolysis not associated with pain. With revision for any reason as an end point, the survivorship was 87% (range, 77%-97%) at 15 years, and considering stem revision only, the survivorship was 93% (confidence interval, 90%-97%) at 15 years. Our data compare favorably with those from series using standard cementless stems at the same followup with a high percentage of patients achieving functional restoration and a low rate of complications., Level of Evidence: Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Unlabelled: Recent literature suggests patients achieve substantial short-term functional improvement after combined bicompartmental implants but longer-term durability has not been documented. We therefore asked whether (1) bicompartmental arthroplasty (either combined medial unicompartmental knee arthroplasty (UKA) and femoropatellar arthroplasty (PFA) or medial UKA/PFA, or combined medial and lateral UKA or bicompartmental UKA) reliably improved Knee Society pain and function scores; (2) bicompartmental arthroplasty was durable (survivorship, radiographic loosening, or symptomatic disease progression); (3) we could achieve durable alignment; and (4) the arthritis would progress in the unresurfaced compartment. We retrospectively reviewed 84 patients (100 knees) with bicompartmental UKA and 71 patients (77 knees) with medial UKA/PFA. Clinical and radiographic evaluations were performed at a minimum followup of 5 years (mean, 12 years; range, 5-23 years). Bicompartmental arthroplasty reliably alleviated pain and improved function. Prosthesis survivorship at 17 years was 78% in the bicompartmental UKA group and 54% in the medial UKA/PFA group. The high revision rate, compared with total knee arthroplasty, may be related to several factors such as implant design, patient selection, crude or absent instrumentation, or component malalignment, which can all contribute to the relatively high failure rate in this series., Level of Evidence: Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Most computer navigation systems used in total hip arthroplasty integrate preoperative pelvic tilt to calculate the anterior pelvic plane assuming tilt is constant; however, the consistency of pelvic tilt after THA has never been proven. Therefore, using a modern comprehensive gait analysis before and after arthroplasty we sought to compare (1) dynamic pelvic tilt changes and (2) pelvic flexion/extension range-of-motion changes. Twenty-one patients who underwent unilateral THA were prospectively studied. Quantitative pelvic tilt changes (in the sagittal plane) and pelvic range of flexion/extension motion relative to a laboratory coordinate system were compared using a computerized video motion system. Mean gait pelvic tilt was 13.9 masculine +/- 4.8 masculine (range, 1.73 masculine-23.1 masculine) preoperatively, 12.5 masculine +/- 4.5 masculine (range, 1.4 masculine-18.7 masculine) 2 months postoperatively, and 10.5 degrees +/- 5.5 masculine (range, -2.36 masculine-19.2 masculine) 12 months postoperatively. A significant proportion (31%) of patients had more than a 5 degrees difference between preoperative and 12-month postoperative measurements and the variability was spread over 20 degrees . Significant dynamic changes in pelvic tilt occurred after THA. While navigation clearly improves the anatomical position of the component during THA, the functional position of the component will not always be improved because of the significant change between preoperative and postoperative pelvic tilt.

Unlabelled: With substantial interest devoted to improving knee flexion after TKA, it is important to document the relationship between high range of motion and patient-rated outcomes shown. We therefore asked whether single-design high-flexion mobile-bearing posterior-stabilized TKA resulted in: (1) improved knee function; (2) satisfying subjective results; (3) participation recreational and sporting activities; and (4) function correlated to the final range of motion. We prospectively followed 445 consecutive patients having 516 TKAs from September 2000 to January 2005. The same high-flexion posterior-stabilized mobile-bearing implant was used in all patients. Mean patient age was 71 +/- 8 years and mean body mass index was 28 +/- 4 kg/m(2). The minimum clinical followup was 2 years (mean, 3 years; range, 2-4 years). The postoperative range of knee flexion was 128 degrees +/- 4 degrees and the mean Knee Society function and knee scores were 91 +/- 6 and 96 +/- 3, respectively. Eighty-two percent of patients were involved in sporting activities and 86% returned to their previous level of activity. These data confirm that high postoperative range of knee flexion improve patient-rated outcomes., Level of Evidence: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Unlabelled: While the literature suggests lateral unicondylar knee arthroplasty (UKA) improves function in the short- and medium-term, it is less clear on longer-term function. We asked (1) whether lateral UKA improved longer-term Knee Society scores and return to previous activity level); (2) whether there were any concerning longer-term radiographic findings (the Knee Society roentgenographic evaluation and scoring system); and (3) whether lateral UKA was durable as measured by survivorship to revision at 10 and 16 years. We retrospectively reviewed 39 patients with 40 lateral cemented metal-backed UKA. The patients had a mean age of 61 years at surgery. The etiologies were primary osteoarthritis in 24 knees, posttraumatic in 12 cases, and osteonecrosis in four cases. We performed clinical and radiographic evaluations at a minimum followup of 3 years (mean, 12.6 years; range, 3-23 years). Prostheses survivorship was 92% at 10 years and 84% at 16 years. Despite the limited number of indications and technical considerations, our data suggest lateral UKA is a reasonable alternative for isolated lateral femorotibial compartment disease., Level of Evidence: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Unlabelled: Unicompartmental knee arthroplasty is a logical procedure when the lesion is limited to one femorotibial compartment. The procedure can now be performed through a mini-incision to provide quicker recovery because the extensor mechanism disruption is minimized. We have found the length of the incision varies according to patient mass and muscle tone. Specific instrumentation limited to the replaced compartment and using either an intra- or extramedullary femoral technique provides femorotibial component alignment and allows slight undercorrection of the deformity. Radiographic assessment demonstrates precise implantation of the components is possible with a mini-incision, which is believed important for the long-term results of the arthroplasty. The functional evaluation of patients implanted with unicompartmental knee arthroplasty performed through a mini-incision suggests appropriate kinematics can be restored after the procedure, enhancing the importance of a functional anterior cruciate ligament., Level of Evidence: Level V, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Unlabelled: The data analyzing clinical and radiological outcomes after modern unicompartmental knee arthroplasty (UKA) for spontaneous and secondary avascular osteonecrosis are limited. We determined whether: (1) UKA for osteonecrosis was as reliable for alleviating pain and improving function (measured by Knee Society scores) as it is for osteoarthritis, (2) lower limb alignment could be restored after UKA for osteonecrosis, and (3) UKA for osteonecrosis is as durable as UKA for osteoarthritis (measured by survivorship at 12 years). We retrospectively reviewed 30 patients (31 knees) with osteonecrosis; 21 knees had spontaneous osteonecrosis and 10 had secondary osteonecrosis. Mean patient age was 71 years. Clinical and radiological evaluations were performed by an independent observer at a minimum followup of 3 years (mean, 7 years; range, 3-16 years). Reliable pain relief and function improvement were obtained in 30 knees (96%). Restoration of an appropriate lower-limb mechanical axis was achieved for 27 knees (88%). The Kaplan-Meier survivorship was 96.7% at 12 years. Our data suggest UKA is a reasonable solution for restoring clinical function and radiological lower-limb alignment for spontaneous or secondary osteonecrosis limited to one compartment of the knee, with a durable survivorship., Level of Evidence: Level IV, retrospective study. See the Guidelines for Authors for a complete description of levels of evidence.

Current indications for high tibial osteotomy (HTO) are controversial although several risk factors have been associated with HTO survival. We ascertained the influence of preoperative variables in a consecutive series of patients who had closing wedge HTO at a minimum of 12 year followup (mean 18-year, range 12 to 28 years). Three hundred one of an initial 372 high tibial osteotomies (313 patients) were included (81% followup); 71 knees were eliminated because patients died (30 knees) or were lost to followup (41 knees). The mean age was 42 years (range, 15-76 years), 194 were men and 119 were women. The osteotomy was fixed by a Blount staple and an AO half-tube plate with three screws. Forty-three knees (14%) in 39 patients were revised for progression of osteoarthritis at an average of 102 months. Survival was 85% at 20 years with revision as the endpoint. Knee function was considered satisfactory by 77% of patients. At final followup, 1/2 of the knees showed radiographic signs of medial osteoarthritis. The most important risk factors predicting revision were age greater than 50 years and a preoperative arthritis Ahlback grade of 3 or more.

Unicompartmental knee arthroplasty is an alternative to total knee arthroplasty for patients with unicompartmental tibiofemoral noninflammatory disease. Careful patient selection and newer instrumentation has reduced the progression of arthrosis in the other compartment and tibial loosening, leaving polyethylene wear as the predominant failure mechanism in more contemporary designs. Increased wear increases the debris volume at the bone-implant interface, and wear particles will generate osteolysis leading to component loosening and unreplaced compartment degeneration. The design-related factors that minimize wear include a polyethylene thickness of greater than 6 mm, a limited shelf age, and a design allowing large areas of contact mediolaterally and anteroposteriorly. Congruous mobile-bearing implants could play a substantial role in reducing wear if they are not associated with dislocation and nonreproducible surgical techniques. Important technical factors include accurate instrumentation avoiding component-to-component malposition and edge loading, allowing slight under-correction of the pre- operative deformity. The patient-related factors include a weight limit, a functional anterior cruciate ligament, and a correctable frontal deformity. Continued research including that related to cross-linking and sterilization methods is mandatory to improve polyethylene strength. A better understanding of kinematics and contact forces may provide long-term survival and patient satisfaction after unicompartmental arthroplasty.

Unlabelled: The rationale for presenting this updated study is to report long-term clinical and survival results of patellofemoral arthroplasty and to ascertain whether the preoperative diagnosis influenced outcomes and therefore indications. We retrospectively updated a previous evaluation of 66 patients who had unilateral patellofemoral arthroplasty between 1972 and 1990. The mean age of the patients at the initial surgery was 57 years (range, 21-82 years). The patients had an average followup of 16.2 years (range, 12-20 years). Preoperative diagnosis included instability, fracture, and primary arthritis. Revision surgery was done in 14 patients for femorotibial osteoarthritis, in 11 for loosening, and in four for stiffness. Survivorship was 58% at 16 years. The knee function score improved from 40 points preoperatively to 81 points at last followup. The best results were in patients with preoperative instability and corrected alignment of the extensor mechanism. Stiffness occurred only in those patients with osteoarthritis from previous fracture. Progressive degeneration of the tibiofemoral joint was noted mainly in the primary osteoarthritis etiologic group. This long-term evaluation of patellofemoral arthroplasty showed the importance of patient selection while excluding knees with significant frontal tibiofemoral malalignment., Level of Evidence: Therapeutic study, Level IV-1 (case series). See the Guidelines for Authors for a complete description of levels of evidence.