Dana L. Judd

Muscle Strength and Functional Recovery During the First Year After THA

BackgroundPatients 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/purposesThe 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.MethodsTwenty-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.ResultsOne 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).ConclusionsPatients 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.Level of EvidenceLevel II, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Weight-Bearing Asymmetry During Sit-Stand Transitions Related to Impairment and Functional Mobility After Total Knee Arthroplasty

OBJECTIVES To examine changes in weight-bearing (WB) asymmetry during sit-stand transitions for individuals during the first 6 months after unilateral total knee arthroplasty (TKA). Relationships between WB asymmetry, clinical measures of knee impairment, and functional mobility also were evaluated. DESIGN Prospective repeated-measures design. SETTING Clinical research laboratory. PARTICIPANTS People (N=36) with knee osteoarthritis (OA) scheduled to undergo unilateral TKA and a control (CTL) group (N=17 healthy people) were enrolled. INTERVENTION The TKA group participated in acute, home, and outpatient phases of exercise-based rehabilitation. MAIN OUTCOME MEASURES WB asymmetry measured during a 5-Times Sit-to-Stand Test (FTSST) based on average vertical ground reaction force under each foot, self-reported knee pain using a numerical pain rating scale, knee active range of motion symmetry, knee extensor strength symmetry, FTSST time, 6-minute walk test distance, and Stair Climbing Test time. RESULTS Compared with preoperative values, the TKA group showed greater WB asymmetry at 1 month after surgery (P<.001). By 6 months, the TKA group had less WB asymmetry than preoperative values (P<.001), which was not different from the CTL group. Symmetry in WB correlated with functional outcomes and symmetry of quadriceps strength for the TKA group 6 months postoperatively. CONCLUSIONS Patients with unilateral knee OA showed WB asymmetry during sit-stand transitions early after unilateral TKA that improved by 6 months after surgery and was no different from that for healthy people of similar age. For people in the first 6 months after TKA, greater symmetry was related to better function and strength symmetry.

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

Abstract 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 activation and coactivation during five-time-sit-to-stand movement in patients undergoing total knee arthroplasty

Quadriceps weakness is prevalent with knee osteoarthritis (OA) and after total knee arthroplasty (TKA). To compensate for quadriceps dysfunction, patients often alter movement strategies. Little is known about muscle coordination during sit-to-stand (concentric) and stand-to-sit (eccentric) movements in the acute postoperative period. This investigation characterized the distribution of muscle activation between the concentric and eccentric phases during a five-time-sit-to-stand (FTSTS) movement in late stage OA and one month after TKA. Patients and healthy participants performed a FTSTS while recording bilateral ground reaction forces (GRFs) and electromyography (EMG). Concentric and eccentric ensemble averages of the GRF and EMG were calculated for the concentric and eccentric phases. Coactivation indices, integrated EMG, and GRF were calculated for each limb and phase. Patients demonstrated higher eccentric coactivation than the healthy group. Postoperative loading was higher in the nonsurgical limb. Postoperative quadriceps activity was lower in the concentric phase and higher in the eccentric phase than the healthy group. Higher coactivation in the patients resulted from sustained distribution of quadriceps activity throughout the eccentric phase. This indicated an inability to coordinate muscle firing when rapidly lowering to a chair and occurred despite unloading of the surgical limb. Although these patterns may serve as a protective strategy, they may also impede recovery of muscle function after TKA.

Muscle strength loss in the lower limb after total knee arthroplasty.

Objective This study aimed to examine functional mobility and strength loss in the ankle plantarflexors and dorsiflexors and knee extensors and flexors after total knee arthroplasty. Design This was a prospective, longitudinal cohort study. Maximal voluntary isometric contractions and gait speed assessments were performed before and after total knee arthroplasty. Results Twenty patients undergoing primary total knee arthroplasty were followed. Repeated-measures analysis of variance results indicated an effect of time on muscle strength, with all muscle groups being significantly weaker (knee extensors, P < 0.001; knee flexors, P < 0.001, ankle plantarflexors, P = 0.004; ankle dorsiflexors, P < 0.001) 1 mo postoperatively. Knee extensors were 42% weaker than preoperative levels, and knee flexors were 34% weaker, whereas the ankle plantarflexors were 17% weaker, and the dorsiflexors were 18% weaker. Three and 6 mos after surgery, strength in all muscle groups was similar to preoperative levels (P > 0.05 for all muscle groups). Patient function followed a similar trend, with patients walking slower 1 mo postoperatively (P < 0.001) and recovering to preoperative levels by 3 and 6 mos after surgery (P > 0.05). Conclusions Patients may benefit from early postoperative rehabilitation, including strengthening of the plantarflexors and dorsiflexors, although strengthening of the quadriceps and hamstrings muscles should continue to be a priority.

Quadriceps/hamstrings co-activation increases early after total knee arthroplasty.

UNLABELLED Quadriceps and hamstrings weakness and co-activation are present following total knee arthroplasty (TKA) and may impair functional performance. How surgery and post-operative rehabilitation influence muscle activation during walking early after surgery is unclear. PURPOSE Examine muscle strength and activation during walking before and one and 6-months post-TKA. METHODS Ten patients (n=6 female; age: 64.7 ± 7.9 years; body mass index[BMI]:29.2 ± 2.5 kg/m(2)) and 10 healthy adults (n=6 female; age: 60.6 ± 7.4 years; BMI: 25.5 ± 4.0 kg/m(2)) participated. The patients underwent bilateral quadriceps and hamstrings strength testing and assessment of quadriceps/hamstrings co-activation and on/off timing using surface electromyography during a six-minute walk test (6MW). Groups, limbs, and changes with TKA surgery were compared. RESULTS Patients reported greater 6MW knee pain pre- versus post-TKA and compared to controls (P<0.05). Patients had weaker surgical limb hamstrings (P<0.05) and bilateral quadriceps (P<0.05) strength than controls pre- and post-TKA. Before and 1-month post-TKA, patients had side-to-side differences in quadriceps and hamstrings strength (P<0.05). Controls walked farther than patients (P<0.01). Patients demonstrated greater surgical limb co-activation pre-operatively than controls (P<0.05). Co-activation was higher bilaterally one-month post-TKA compared to controls (P<0.05). Patients turned off their quadriceps later during stance than controls before and 1-month post-TKA (P<0.05). CONCLUSIONS Muscle strength, co-activation, and timing differed between patients and controls before and early after surgery. Rehabilitation to improve strength and muscle activation seems imperative to restore proper muscle firing patterns early after surgery.

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

ObjectiveThe purpose of this study was to explore the relationship between patients’ self-reported and performance-based function after total hip arthroplasty (THA). DesignTwenty-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. ResultsOne 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. ConclusionThe 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 neuromuscular reeducation on hip mechanics and functional performance in patients after total hip arthroplasty: A case series.

BACKGROUND Following total hip arthroplasty, patients demonstrate compensatory movement strategies during activities of daily living such as walking and stair climbing. Movement compensations are important markers of functional decline in older adults and are related to poor functional capacity. Despite increased utilization of hip arthroplasty, persistent movement compensation, and functional performance deficits, no consensus on postoperative rehabilitation exists. Neuromuscular reeducation techniques offer a strategy to improve movement quality by emphasizing hip abductor performance and pelvic stability. This case series illustrates changes in movement strategy around the hip in response to targeted neuromuscular reeducation techniques after hip arthroplasty. METHODS Five participants received an 8-week exercise program following total hip arthroplasty, emphasizing targeted neuromuscular reeducation techniques hallmarked by specific, weight-bearing exercise to improve hip abductor performance and pelvic stability. Five additional participants were supervised and followed for comparison. FINDINGS Participants in the neuromuscular reeducation program improved their internal hip abductor moments and vertical ground reaction forces during walking and stair climbing. They also improved their functional performance and hip abductor strength outcomes. INTERPRETATION Targeted neuromuscular reeducation techniques after total hip arthroplasty provided a positive effect on biomechanical outcomes, functional performance, and muscle strength. Through focused use of the hip abductor muscles, increased internal hip abductor moments were observed. This intervention potentially promotes pelvic stability, and may contribute to improved performance on tasks such as stair climbing, fast walking, and balance. The results suggest that neuromuscular reeducation offers a unique effect on movement strategy and function for patients following total hip arthroplasty.

The impact of hip implant alignment on muscle and joint loading during dynamic activities

Background Component alignment is an important consideration in total hip arthroplasty. The impact of changes in alignment on muscle forces and joint contact forces during dynamic tasks are not well understood, and have the potential to influence surgical decision making. The objectives of this study were to assess the impact of femoral head/stem and cup component placement on hip muscle and joint contact forces during tasks of daily living and to identify which alignment parameters have the greatest impact on joint loading. Methods Using a series of strength‐calibrated, subject‐specific musculoskeletal models of patients performing gait, sit‐to‐stand and step down tasks, component alignments were perturbed and joint contact and muscle forces evaluated. Findings Based on the range of alignments reported clinically, variation in head/stem anteversion‐retroversion had the largest impact of any degree of freedom throughout all three tasks; average contact forces 413.5 (319.1) N during gait, 262.7 (256.4) N during sit to stand, and 572.7 (228.1) N during the step down task. The sensitivity of contact force to anteversion‐retroversion of the head/stem was 31.5 N/° for gait, which was similar in magnitude to anterior‐posterior position of the cup (34.6 N/m for gait). Additionally, superior‐inferior cup alignment resulted in 16.4 (4.9)° of variation in the direction of the hip joint contact force across the three tasks, with the most inferior cup placements moving the force vector towards the cup equator at the point of peak joint contact force. Interpretation A quantitative understanding of the impact and potential tradeoffs when altering component alignment is valuable in supporting surgical decision making. HighlightsHip arthroplasty alignment parameters with greatest impact on loading were identified.Subject‐specific musculoskeletal models simulating daily activities were used.Head/stem anteversion‐retroversion had the largest impact throughout all three tasks.Inferior cup placements resulted in forces towards the cup equator at peak loads.Alignment impact supports surgical decision‐making and instrumentation development.