Strain-mode-specific mechanical testing and the interpretation of bone adaptation in the deer calcaneus.

The artiodactyl (deer and sheep) calcaneus is a model that helps in understanding how many bones achieve anatomical optimization and functional adaptation. We consider how the dorsal and plantar cortices of these bones are optimized in quasi-isolation (the conventional view) versus in the context of load sharing along the calcaneal shaft by "tension members" (the plantar ligament and superficial digital flexor tendon). This load-sharing concept replaces the conventional view, as we have argued in a recent publication that employs an advanced analytical model of habitual loading and fracture risk factors of the deer calcaneus. Like deer and sheep calcanei, many mammalian limb bones also experience prevalent bending, which seems problematic because the bone is weaker and less fatigue-resistant in tension than compression. To understand how bones adapt to bending loads and counteract deleterious consequences of tension, it is important to examine both strain-mode-specific (S-M-S) testing (compression testing of bone habitually loaded in compression; tension testing of bone habitually loaded in tension) and non-S-M-S testing. Mechanical testing was performed on individually machined specimens from the dorsal "compression cortex" and plantar "tension cortex" of adult deer calcanei and were independently tested to failure in one of these two strain modes. We hypothesized that the mechanical properties of each cortex region would be optimized for its habitual strain mode when these regions are considered independently. Consistent with this hypothesis, energy absorption parameters were approximately three times greater in S-M-S compression testing in the dorsal/compression cortex when compared to non-S-M-S tension testing of the dorsal cortex. However, inconsistent with this hypothesis, S-M-S tension testing of the plantar/tension cortex did not show greater energy absorption compared to non-S-M-S compression testing of the plantar cortex. When compared to the dorsal cortex, the plantar cortex only had a higher elastic modulus (in S-M-S testing of both regions). Therefore, the greater strength and capacity for energy absorption of the dorsal cortex might "protect" the weaker plantar cortex during functional loading. However, this conventional interpretation (i.e., considering adaptation of each cortex in isolation) is rejected when critically considering the load-sharing influences of the ligament and tendon that course along the plantar cortex. This important finding/interpretation has general implications for a better understanding of how other similarly loaded bones achieve anatomical optimization and functional adaptation.

Exploration of the synergistic role of cortical thickness asymmetry ("Trabecular Eccentricity" concept) in reducing fracture risk in the human femoral neck and a control bone (Artiodactyl Calcaneus).

The mechanobiology of the human femoral neck is a focus of research for many reasons including studies that aim to curb age-related bone loss that contributes to a near-exponential rate of hip fractures. Many believe that the femoral neck is often loaded in rather simple bending, which causes net tension stress in the upper (superior) femoral neck and net compression stress in its inferior aspect ("T/C paradigm"). This T/C loading regime lacks in vivo proof. The "C/C paradigm" is a plausible alternative simplified load history that is characterized by a gradient of net compression across the entire femoral neck; action of the gluteus medius and external rotators of the hip are important in this context. It is unclear which paradigm is at play in natural loading due to lack of in vivo bone strain data and deficiencies in understanding mechanisms and manifestations of bone adaptation in tension vs. compression. For these reasons, studies of the femoral neck would benefit from being compared to a 'control bone' that has been proven, by strain data, to be habitually loaded in bending. The artiodactyl (sheep and deer) calcaneus model has been shown to be a very suitable control in this context. However, the application of this control in understanding the load history of the femoral neck has only been attempted in two prior studies, which did not examine the interplay between cortical and trabecular bone, or potential load-sharing influences of tendons and ligaments. Our first goal is to compare fracture risk factors of the femoral neck in both paradigms. Our second goal is to compare and contrast the deer calcaneus to the human femoral neck in terms of fracture risk factors in the T/C paradigm (the C/C paradigm is not applicable in the artiodactyl calcaneus due to its highly constrained loading). Our third goal explores interplay between dorsal/compression and plantar/tension regions of the deer calcaneus and the load-sharing roles of a nearby ligament and tendon, with insights for translation to the femoral neck. These goals were achieved by employing the analytical model of Fox and Keaveny (J. Theoretical Biology 2001, 2003) that estimates fracture risk factors of the femoral neck. This model focuses on biomechanical advantages of the asymmetric distribution of cortical bone in the direction of habitual loading. The cortical thickness asymmetry of the femoral neck (thin superior cortex, thick inferior cortex) reflects the superior-inferior placement of trabecular bone (i.e., "trabecular eccentricity," TE). TE helps the femoral neck adapt to typical stresses and strains through load-sharing between superior and inferior cortices. Our goals were evaluated in the context of TE. Results showed the C/C paradigm has lower risk factors for the superior cortex and for the overall femoral neck, which is clinically relevant. TE analyses of the deer calcaneus revealed important synergism in load-sharing between the plantar/tension cortex and adjacent ligament/tendon, which challenges conventional understanding of how this control bone achieves functional adaptation. Comparisons with the control bone also exposed important deficiencies in current understanding of human femoral neck loading and its potential histocompositional adaptations.

Neuromuscular electrical stimulation preserves muscle strength early after total knee arthroplasty: Effects on muscle fiber size.

Loss of quadriceps strength after total knee arthroplasty (TKA) is most pronounced acutely but persists long-term, negatively impacting physical function in daily activities. Neuromuscular electrical stimulation (NMES) early after surgery is an effective adjuvant to standard of care rehabilitation (SOC) for attenuating strength loss following TKA, but the mechanisms whereby NMES maintains strength are unclear. This work aimed to determine the effects of early NMES on quadriceps strength and skeletal muscle fiber size 2 weeks after TKA compared to SOC. Patients scheduled for primary, unilateral TKA were enrolled and randomized into SOC (n = 9) or NMES plus SOC (n = 10) groups. NMES was started within 48 h of TKA, with 45-min sessions twice a day for 2 weeks. Isometric quadriceps strength was assessed preoperatively and 2 weeks following TKA. Vastus lateralis muscle biopsies of the involved leg were performed at the same time points and immunohistochemistry conducted to assess muscle fiber cross-sectional area and distinguish fiber types. Groups did not differ in age, body mass index, sex distribution, or preoperative strength. Both groups got weaker postoperatively, but the NMES group had higher normalized strength. After 2 weeks, the group receiving NMES and SOC had significantly greater MHC IIA and MHC IIA/IIX fiber size compared to SOC alone, with no group differences in MHC I fiber size. These results suggest that NMES mitigates early muscle weakness following TKA, in part, via effects on fast-twitch, type II muscle fiber size. This investigation advances our understanding of how adjuvant, early postoperative NMES aids muscle strength recovery.

Influence of Body Bass Index (BMI) on post-operative Opioid Requirements in Primary Total Joint Arthroplasty Patients.

BACKGROUND: The aim of our study was to evaluate whether an association exists between body mass index (BMI) category and post-operative opioid requirements among primary total joint arthroplasty (TJA) patients. METHODS: We retrospectively reviewed all primary unilateral total hip and total knee arthroplasty (THA/TKA, respectively) cases performed over a two-year period. We evaluated whether a relationship exists between five BMI categories (≤24.9, 25-29.9, 30-34.9, 35-39.9, ≥40) and morphine milligram equivalent (MME) use for total in-hospital, daily in-hospital, and total during six weeks post-discharge. Secondary outcomes included relationship with length of stay, discharge location, opioid refill rate, and pre-operative opioid usage. RESULTS: For all patients undergoing primary TJA, increasing BMI resulted in an incremental increase in post-operative total in-hospital MME use for each successive BMI category when compared to those with BMI ≤24.9 (p < 0.05). This association held true for the THA subset. Within the cohort as a whole, higher categories of BMI were associated with increased length of stay (35-39.9, ≥40), higher odds of needing a refill (30-34.9, 35-39.9, ≥40), and higher odds of discharging to a rehab facility (25-29.9, ≥40) (p < 0.05). There was an increasing proportion of pre-operative opioid use as BMI category increased (p < 0.0001). DISCUSSION/CONCLUSION: BMI category is associated with increased in-hospital opioid requirements among primary TJA patients. Such findings are an important step to better understanding pain control expectations and can help facilitate development of opioid reduction strategies.

Movement pattern biofeedback training after total knee arthroplasty: Randomized clinical trial protocol.

INTRODUCTION: Total knee arthroplasty (TKA) reduces joint symptoms, but habitual movement compensations persist years after surgery. Preliminary research on movement training interventions have signaled initial efficacy for remediating movement compensations and restoring knee joint loading symmetry during dynamic functional tasks after TKA. The purpose of this clinical trial is to determine if physical rehabilitation that includes movement training restores healthy movement patterns after TKA and reduces the risk of osteoarthritis (OA) progression in the contralateral knee. METHODS/DESIGN: 150 participants will be enrolled into this randomized controlled trial. Participants will be randomly allocated to one of two dose-equivalent treatment groups: standard rehabilitation plus movement training (MOVE) or standard rehabilitation without movement training (CONTROL). Movement training will promote between-limb symmetry and surgical knee loading during activity-based exercises. Movement training strategies will include real-time biofeedback using in-shoe pressure sensors and verbal, visual, and tactile cues from the physical therapist. The primary outcome will be change in peak knee extension moment in the surgical knee during walking, from before surgery to six months after surgery. Secondary outcomes will include lower extremity movement symmetry during functional tasks, physical function, quadriceps strength, range of motion, satisfaction, adherence, contralateral knee OA progression, and incidence of contralateral TKA. DISCUSSION: This study will provide insights into the efficacy of movement training after unilateral TKA, along with mechanisms for optimizing long-term physical function and minimizing negative sequelae of compensatory movement patterns.

Benefits of direct patient discharge to outpatient physical therapy after total knee arthroplasty.

Purpose: To investigate the effectiveness of home health physical therapy followed by outpatient physical therapy as compared to patients discharged directly to outpatient physical therapy in improving functional performance, strength/activation and residual knee pain outcomes among patients who received a total knee arthroplasty.Materials and methods: A secondary analysis of longitudinal data in which patients with total knee arthroplasty underwent home health physical therapy or were discharged directly to outpatient physical therapy. Main outcome measures included the stair climb test, timed up and go, 6-min walk test, quadriceps and hamstring strength, quadriceps activation and residual knee pain.Results: Patients referred to home health physical therapy prior to outpatient physical therapy demonstrated significantly greater declines in stair climb test (10.3; 95% CI [6.5, 14.1]; t = 5.41; p < 0.0001), timed up and go (2.0; 95% CI [1.0, 3.0]; t = 4.10; p < 0.0001), 6-min walk (53.8; 95% CI [29.4, 78.2]; t = 4.35; p < 0.0001), quadriceps strength (21.7%; 95% CI [19.3%, 24.9%]; t = 2.53; p = 0.01), hamstring strength (44.7%; 95% CI [43.4%, 45.7%], t = 3.17; p = 0.002) and higher residual knee pain (0.53; 95% CI [0.04, 1.03]; t = 2.17; p = 0.03) 1 month after total knee arthroplasty compared to those referred directly to outpatient physical therapy.Conclusions: These findings suggest that patients discharged directly to outpatient physical therapy had a more rapid recovery 1 month after total knee arthroplasty. Additional research is needed to investigate the potential causal relation between care pathways and clinical outcomes following total knee arthroplasty.Implications for rehabilitationTotal knee arthroplasty, typically performed to alleviate end-stage knee osteoarthritis, is the most commonly performed elective surgery in the United States.Despite improvement in pain, objective measurements of functional performance and strength often remain at preoperative levels one year after total knee arthroplasty.Patients discharged directly to higher intensity outpatient physical therapy have a more rapid recovery after total knee arthroplasty compared with those patients who received two weeks of home health prior to undergoing outpatient physical therapy.

Peripheral Nociception Is Associated with Voluntary Activation Deficits and Quadriceps Weakness Following Total Knee Arthroplasty.

BACKGROUND: Quadriceps weakness is a hallmark of total knee arthroplasty and is driven by reduced voluntary muscle activation following the surgical procedure. The mechanisms underlying postoperative activation deficits are not well established, although nociception has been implicated via both spinal reflex and supraspinal pathways. The purpose of this study was to assess the role of nociception in postoperative recovery of strength and activation. METHODS: A total of 53 participants were assessed prior to total knee arthroplasty and at 6 weeks postoperatively. Quadriceps strength was measured by maximum voluntary isometric contraction, and activation was measured by the doublet interpolation technique. The pressure-pain threshold was used to measure local sensitization (at the knee joint) and systemic sensitization (at the forearm). Changes in outcomes (strength and activation) were regressed against pressure-pain threshold measurements. Mediation analyses were planned for significant associations to investigate whether deficits in voluntary activation were implicated on a causal pathway between pressure-pain threshold measures and postoperative strength loss. RESULTS: Knee pressure-pain threshold measures were significantly associated with reduced voluntary quadriceps activation (beta = -0.04; p = 0.009) and diminished quadriceps strength after total knee arthroplasty (beta = -0.07; p = 0.001). There was also a mediation effect of voluntary activation on the relationship between the knee pressure-pain threshold and quadriceps strength. After correcting for multiple comparisons, relationships between the forearm pressure-pain threshold and strength and activation did not reach significance. CONCLUSIONS: The measures of local nociceptor sensitization were related to reduced strength and activation following total knee arthroplasty. This is consistent with a causal pathway linking increased firing of knee joint nociceptors to reduced activation and reduced strength. Future randomized studies should investigate whether peripherally directed pain therapies reduce pain while also promoting the recovery of quadriceps strength via an improved capacity for voluntary activation. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Trajectories of functional performance and muscle strength recovery differ after total knee and total hip replacement: a performance-based, longitudinal study.

Total joint replacement is indicated to alleviate pain and disability associated with hip and knee osteoarthritis. Arthroplasty outcomes are typically reported together, or anecdotal comparisons are made between total knee arthroplasty (TKA) and total hip arthroplasty (THA) recovery. Limited data quantifies differences in recovery trajectories, especially with respect to performance-based outcomes. Seventy-nine people undergoing total knee or THA were followed over 6 months. Functional performance was measured using the stair climb test, timed-up-and-go test, and 6-min walk test. Surgical limb isometric strength was also measured. All outcomes significantly declined 1 month after surgery. Participants in the TKA group showed a greater decline in climbing stairs (P < 0.001), timed-up-and-go (P = 0.01), and 6-min walk distance (P < 0.01). Further, the TKA group lost more strength (P < 0.001) and were weaker than those after THA (P < 0.001). Differences in postoperative outcomes between groups at 3 and 6 months were also observed. The TKA group experiences a greater decline in measured outcomes than the THA group, and muscle strength and functional recovery occurred differently in each group. These findings should be considered in rehabilitation priorities after arthroplasty surgery.

The Role of Complete Posterior Cruciate Ligament Release in Flexion Gap Balancing for Total Knee Arthroplasty.

BACKGROUND: The sequence of posterior cruciate ligament (PCL) release in posterior-substituting designs, when performing gap balancing in total knee arthroplasty (TKA), is variable. We hypothesize that early complete PCL release during knee exposure will change the flexion balance to result in a uniform medial-lateral flexion gap symmetry at the time of implant placement. METHODS: Ten cadaveric knees were prepared for TKA using standard medial parapatellar approach. Medial and lateral flexion gaps were measured in the conditions of intact, partial (50%) resection, and full resection of PCL. Measurements were performed with both surgical navigation and a caliper. Flexion gap distances were reported for medial and lateral compartments in the 3 PCL conditions. RESULTS: Medial flexion gap increased after only complete release of the PCL (mean 3.94-5.05 mm). The lateral flexion gap increased as well (mean 4.17-4.67 mm). Complete PCL release resulted in a statistically significant increase in medial flexion gap compared to intact (P = .013) and partially released (P = .012) specimens. No significant differences were noted in lateral flexion gap change. Notable change in medial versus lateral gap (flexion gap symmetry) relationship occurred after just partial PCL release (P = .018). CONCLUSION: Among the 3 PCL states, changes in flexion gap distance were most conspicuous in the medial compartment. This suggests gap balancing performed with incomplete PCL release will not accurately reflect gap distance after eventual PCL removal, thus supporting the hypothesis. It is recommended that the PCL should be released to the fullest extent possible before ligament tensioning for femoral component rotation in posterior-stabilized TKA.

Correction to: The relationship of pelvic incidence to post-operative total hip arthroplasty dislocation in patients with lumbar fusion.

The original publication of this paper contain an error. The author name "Alan S. McGee Jr" is incorrect for it should have been "Alan W. McGee Jr".

The relationship of pelvic incidence to post-operative total hip arthroplasty dislocation in patients with lumbar fusion.

PURPOSE: To determine if lumbar fusion increases the risk of dislocation following total hip arthroplasty (THA) via a posterior approach and to investigate anatomic variables associated with this increased risk. METHODS: Five-year retrospective review of THAs performed through a posterior approach identifying cases of post-operative dislocation. Patients were grouped into those with or without previous lumbar spine fusion. Lumbar fusion patients were then further analyzed in terms of cup position, pelvic incidence, sacral slope, and pelvic tilt to determine if there were specific variables associated with the increased risk of dislocation. RESULTS: Five hundred nine primary THAs in 460 patients (non-simultaneous bilateral THAs in 41 patients) met inclusion criteria with a dislocation rate of 5.5%. Thirty-one patients were identified as having prior lumbar fusions. The dislocation rate was significantly higher in fusion patients (29 vs 4%; p = 0.009) yielding a relative risk (RR) of dislocation of 4.77 (p = < 0.0001). Additionally, cup anteversion was significantly different between groups (26.8 vs 21.42; p = 0.009). Dislocators in the fusion group were also at greater risk of requiring subsequent revision (RR = 3.24; p = 0.003). Subgroup analysis of fusion patients revealed that dislocators had lower pelvic incidence and sacral slope compared to non-dislocators (45.2 vs 58.6 [p = 0.0029] and 26.3 vs 35.6 [p = 0.0384] respectively). CONCLUSIONS: Patients with lumbar fusion are at increased risk for post-operative dislocations requiring revision. Together, lower pelvic incidence and decreased sacral slope are associated with increased risk of dislocation in these patients.

A Cross-sectional Analysis of Minimum USMLE Step 1 and 2 Criteria Used by Orthopaedic Surgery Residency Programs in Screening Residency Applications.

INTRODUCTION: The purpose of this study was to analyze how program directors (PDs) of orthopaedic surgery residency programs use United States Medical Licensing Examination (USMLE) Step 1 and 2 scores in screening residency applicants. METHODS: A survey was sent to each allopathic orthopaedic surgery residency PD. PDs were asked if they currently use minimum Step 1 and/or 2 scores in screening residency applicants and if these criteria have changed in recent years. RESULTS: Responses were received from 113 of 151 PDs (75%). One program did not have the requested information and five declined participation, leaving 107 responses analyzed. Eighty-nine programs used a minimum USMLE Step 1 score (83%). Eighty-three programs (78%) required a Step 1 score ≥210, 80 (75%) required a score ≥220, 57 (53%) required a score ≥230, and 22 (21%) required a score ≥240. Multiple PDs mentioned the high volume of applications as a reason for using a minimum score and for increasing the minimum score in recent years. DISCUSSION: A large proportion of orthopaedic surgery residency PDs use a USMLE Step 1 minimum score when screening applications in an effort to reduce the number of applications to be reviewed.

Safety and efficacy of resistive polymer versus forced air warming in total joint surgery.

BACKGROUND: Forced-air warming is used as a mechanism to prevent hypothermia and adverse outcomes associated with hypothermia among patients undergoing surgery. Patient safety in healthcare includes the use of devices and technology that minimize potential adverse events to patients. The present study sought to compare the capabilities of patient warming between two different devices that use different mechanisms of warming: forced-air warming and non-air warming. METHODS: One hundred twenty patients undergoing total hip or total knee arthroplasty received patient warming via a forced warming device or non-air warming fabric conductive material. The project was part of a quality improvement initiative to identify warming devices effective in maintaining normothermic patient core temperatures during orthopedic surgery. RESULTS: Forced-air warming and non-air warming achieved similar results in maintaining the core temperature of patients undergoing total knee or hip arthroplasty. No adverse events were reported in either group. Operating room staff observed that the non-air warming device was less noisy and appreciated the disposable covers that could be changed after each surgical case. CONCLUSIONS: These findings demonstrate that hypothermia is achieved by both forced-air and non-forced air warming devices among total knee and hip arthroplasty patients. The potential for airflow disruption is present with the forced-air warming device and does not exist with the non-forced air device. The disruption of laminar airflow may be associated with surgical site infections. The disposable covers used to protect the device and patient have potential implications for surgical site infection. Quality improvement efforts aimed to enhance patient safety should include the implementation of healthcare equipment with the least known or suspected risk.

A Comparison of Matched and Unmatched Orthopaedic Surgery Residency Applicants from 2006 to 2014: Data from the National Resident Matching Program.

BACKGROUND: The Association of American Medical Colleges publishes residency match data and reports through the National Resident Matching Program (NRMP) every year. The purpose of this study was to analyze trends in orthopaedic surgery residency matching data and characteristics of successful applicants to counsel medical students with regard to their chances of matching. METHODS: The annual reports of the NRMP were searched annually from 2006 to 2014 to determine the number of orthopaedic surgery residency positions available, the number of applicants, and the match rate among applicants. Comparisons were performed between matched applicants and unmatched applicants with regard to the number of contiguous ranks and distinct specialties, United States Medical Licensing Examination (USMLE) scores, number of research experiences and research products (abstracts, presentations, posters, publications), and proportion of Alpha Omega Alpha (AOA) Honor Medical Society members and students at a top-40, National Institutes of Health (NIH)-funded medical school. RESULTS: The number of orthopaedic surgery positions available and number of applicants increased at a mean rate of 9 positions and 65 applicants per year (p = 0.11). The mean number of contiguous ranks for U.S. senior medical students was 11.5 for those who matched and 5.5 for those who did not match (p < 0.0001). The USMLE scores for applicants who matched were significantly greater than for those who did not match in each category: Step-1 scores for U.S. seniors (p < 0.001) and independent applicants (p = 0.039), and Step-2 scores for U.S. seniors (p < 0.01) and independent applicants (p = 0.026). The mean number of research products was significantly greater for matched U.S. seniors compared with unmatched U.S. seniors (p = 0.035). A significantly higher proportion of matched U.S. seniors compared with unmatched U.S. seniors were AOA members and students at a top-40, NIH-funded medical school (both p < 0.0001). CONCLUSIONS: Successful applicants in the Match for orthopaedic surgery residency have higher USMLE Step-1 and 2 scores, number of research experiences and research products, and contiguous ranks. A higher proportion of successful applicants are AOA members and students at a top-40, NIH-funded medical school.

Perioperative blood loss in total hip and knee arthroplasty: Outcomes associated with intravenous tranexamic acid use in an academic medical center.

OBJECTIVES: Clinical trials have reported decreased blood loss with the use of tranexamic acid during joint reconstruction. The purpose of this study was to assess the individual practice implications of tranexamic acid use in joint replacement surgery. METHODS: Health records of adults undergoing total knee arthroplasty and total hip arthroplasty over a 12-month period were retrospectively reviewed. The treatment group comprised patients who received intravenous tranexamic acid perioperatively. The control group comprised patients who did not receive tranexamic acid. RESULTS: Patients in the treatment group (n = 64) and the control group (n = 99) were well matched for demographics, orthopedic diagnosis, and comorbidities. In-hospital postsurgical mean decreases in hemoglobin concentrations were -4.05 g/dL and -4.94 g/dL in the treatment and control groups, respectively (p < 0.001). Postsurgical mean decreases in hematocrit levels were -11.2% and -14.2% in the treatment and control groups, respectively (p < 0.001). Three patients in the treatment group (5%) and 21 patients in the control group (21%) received red blood cell transfusions (p = 0.006). As compared to control, the relative risk of transfusion in the treatment group was 0.23 (95% confidence interval = 0.07-0.76) and the number needed to treat to avoid one transfusion was 7.0 (95% confidence interval = 3.8-14.4). No evidence of thromboembolism or other serious complications were observed in either group. CONCLUSIONS: In patients undergoing joint replacement surgery, perioperative administration of tranexamic acid was associated with diminished blood loss and lesser resource utilization.

Clinical and Functional Outcomes of the Birmingham Hip Resurfacing System.

This study reported the outcomes of patients treated with the Birmingham Hip Resurfacing System (Smith & Nephew, Memphis, Tennessee) to identify the prevalence of complications and failures. A retrospective review of 202 patients (206 hips) was performed. Outcomes were assessed clinically with Harris Hip Score at 6 and 12 months and then yearly. Subanalysis was performed, with the hips divided according to patient sex and size of the femoral component. Mean patient age was 51±8 years, and mean follow-up was 4±1.6 years. Of the patients, 163 were men (83%) and 35 were women (17%). Postoperative improvement was significant, with preoperative Harris Hip Score of 62.9±10.6 and postoperative Harris Hip Score of 98.6±6.7 (P<.001). There were 9 patients (4%) who had complications. A total of 5 hips (2.4%) underwent revision. At 3 years, mean survival was better for men than for women (99% vs 92%, respectively). Survival was lowest in patients with femoral component diameter of less than 46 mm. According to the authors' results, the Birmingham Hip Resurfacing System resulted in good clinical outcomes at 4 years. Survival and outcomes in women, particularly those with modest bone size, are inferior.

Performance-Based Versus Self-Reported Outcomes Using the Hip Disability and Osteoarthritis Outcome Score After Total Hip Arthroplasty.

OBJECTIVE: The purpose of this study was to explore the relationship between patients' self-reported and performance-based function after total hip arthroplasty (THA). DESIGN: Twenty-three patients (age, 61.4 ± 8.3 yrs) undergoing primary THA for hip osteoarthritis participated. Self-reported function and recovery was measured using the Hip Disability and Osteoarthritis Outcome Score activities of daily living and pain subscales. Performance-based functional measures included the timed up and go test, the stair climbing test, and the 6-minute walk test. Outcome measures were assessed preoperatively and postoperatively at 1 and 6 mos. RESULTS: One month after THA, performance-based function declined compared with baseline as follows: timed up and go test, -22.1% ± 25.4%; stair climbing test, -58.5% ± 63.6%; and 6-minute walk test, -22.6% ± 31.7%. In contrast, self-reported function on the Hip Disability and Osteoarthritis Outcome Score Activities of Daily Living significantly improved 1 mo after THA compared with baseline: 40.8% ± 33.3%. One to 6 mos after THA, there were significant improvements in timed up and go test, stair climbing test, and 6-minute walk test, which paralleled improvements on the Hip Disability and Osteoarthritis Outcome Score subscales, although changes were not significantly correlated. CONCLUSION: The disparity between changes in Hip Disability and Osteoarthritis Outcome Scores and functional performance postoperatively suggests that patients may overestimate their functional capacity early after THA, likely in response to pain improvements over the same time period. Therefore, outcomes assessment after THA should include both self-report and performance-based functional measures.

Effects of Weight-Bearing Biofeedback Training on Functional Movement Patterns Following Total Knee Arthroplasty: A Randomized Controlled Trial.

STUDY DESIGN: Randomized controlled trial. OBJECTIVES: To examine the effects of weight-bearing biofeedback training on weight-bearing symmetry and functional joint moments following unilateral total knee arthroplasty. BACKGROUND: Individuals after unilateral total knee arthroplasty place more weight on the nonsurgical limb compared to the surgical limb during function. It is unknown whether targeted intervention can improve function in the surgical limb and resolve altered movement patterns. METHODS: Twenty-six patients were randomly assigned to 2 groups (reload or control). The reload group had a standard-of-care rehabilitation augmented with weight-bearing biofeedback training, and the control group had a dose-matched standard-of-care rehabilitation. Lower-limb weight-bearing ratios were measured preoperatively and 6 and 26 weeks after total knee arthroplasty during a 5-time sit-to-stand test (FTSST) and walking. Secondary outcomes were FTSST time, walking speed, and lower-limb joint moments during the FTSST and walking. RESULTS: No between-group differences were found in weight-bearing ratios. Five-time sit-to-stand test time improved in the reload group compared to the control group at 6 (P = .021) and 26 weeks (P = .021). There were no between-group differences in knee extension moment during the FTSST. Surgical-limb knee extension moments during walking increased from baseline to 26 weeks in the reload group and decreased in the control group (P = .008). CONCLUSION: Weight-bearing biofeedback training had no effect on functional weight-bearing symmetry or knee extension moments during the FTSST. However, the biofeedback training resulted in increases of knee extension moments during gait and improved FTSST times. Trial registered at ClinicalTrials.gov (NCT01333189). Level of Evidence Therapy, level 2b.

Strength and functional deficits in individuals with hip osteoarthritis compared to healthy, older adults.

PURPOSE: Hip osteoarthritis (OA) compromises quality of life for many individuals. This study quantified deficits in functional capacity for use in rehabilitation goal setting by combining assessments of muscle strength, function and physical activity in patients with hip OA and healthy adults. METHOD: Twenty-six patients with end-stage hip OA and 18 healthy adults participated. Isometric muscle strength around the hip and knee was measured. Function was assessed using stair climbing, five-time-sit-to-stand, timed-up-and-go and 6-minute walk tests. The UCLA activity rating scale assessed physical activity. Analyses of covariance (ANCOVA) were used to assess differences between groups. RESULTS: Patients had 30% less knee extensor (p < 0.001), 38% less knee flexor (p < 0.001), 10% less hip flexor (p = 0.47), 23% less hip extensor (p = 0.24) and 17% less hip abductor strength (p = 0.23) than healthy adults. Hip adductor strength was equal between groups (p = 0.93). Patients were 50% slower on the stair climbing test (p = 0.001), 34% slower on the timed-up-and-go test (p = 0.004), 34% slower on the five-time-sit-to-stand test (p = 0.001), and walked 28% less during the 6-min walk test (p < 0.001). Patients were less physically active (p = 0.001). CONCLUSIONS: Patients had deficits in muscle strength, function and physical activity compared to healthy adults. Quantifying these deficits provides benchmarks for improvement during rehabilitation. IMPLICATIONS FOR REHABILITATION: Hip osteoarthritis (OA) affects up to 28% of adults over the age of 65 and many individuals report functional and activity limitations directly related to their arthritic condition, posing a risk for future morbidity Total hip arthroplasty (THA) is the treatment of choice for decreasing pain and improving function, however, some individuals suffering from end-stage hip OA are not candidates for THA, and effective rehabilitation interventions to improve physical function are crucial Establishing estimates of the deficits in muscle strength, physical function and physical activity in people with and without hip OA can aid rehabilitation professionals in their goal setting and intervention planning Rehabilitation interventions should not only consist of muscle strengthening and functional training, but interventions to improve physical activity levels are required to improve overall physical functioning and to decrease risks for additional health complications.

Muscle strength and functional recovery during the first year after THA.

BACKGROUND: Patients undergoing total hip arthroplasty (THA) often are satisfied with the decrease in pain and improvement in function they achieve after surgery. Even so, strength and functional performance deficits persist after recovery, but these remain poorly characterized; knowledge about any ongoing strength or functional deficits may allow therapists to design rehabilitation programs to optimize recovery after THA. QUESTIONS/PURPOSES: The purposes of this study were to (1) evaluate postoperative muscle strength, function, and quality of life during the first year after THA; and (2) compare strength and function in patients 1 year after THA with a cohort of healthy peers. METHODS: Twenty-six patients undergoing THA were assessed 1, 3, 6, and 12 months postoperatively, and 19 adults with no hip pathology were tested as a control group. Isometric muscle strength (hip flexors, extensors, abductors, knee extensors, and flexors), functional performance (stair climbing, five times sit-to-stand, timed-up-and-go, 6-minute walk, and single-limb stance tests), and self-reported function (Hip Disability and Osteoarthritis Score, SF-36, and UCLA activity score) were compared. RESULTS: One month after THA, patients had 15% less hip flexor and extensor torque, 26% less abductor torque, 14% less knee extensor and flexor torque, and worse performance on the stair climbing, timed-up-and-go, single-limb stance, and 6-minute walk. Compared with healthy adults, patients 12 months after THA had 17% less knee extensor and 23% less knee flexor torque; however, the functional testing (including stair climbing, five times sit-to-stand, and the 6-minute walk) showed no significant differences with the patient numbers available between individuals undergoing THA and healthy control subjects. SF-36 Physical Component Scores, although significantly improved from preoperative levels, were significantly worse than healthy adults 1 year after THA (p < 0.01). CONCLUSIONS: Patients experience early postoperative strength losses and decreased functional capacity after THA, yet strength deficits may persist after recovery. This may suggest that rehabilitation may be most effective in the first month after surgery.