Effects of resistance training in older women with knee osteoarthritis and total knee arthroplasty

OBJECTIVES:

This study sought to analyze the effects of resistance training on functional performance, lower-limb loading distribution and balance in older women with total knee arthroplasty (TKA) and osteoarthritis (OA) in the contralateral knee. In addition, this older knee OA and TKA group (OKG) was compared to older (OG) and young women (YG) without musculoskeletal diseases who underwent the same resistance training program.

METHODS:

Twenty-three women divided into OKG (N = 7), OG (N = 8) and YG (N = 8) had their functional performance, lower-limb loading distribution and balance compared before and after 13 weeks of a twice-weekly progressive resistance training program.

RESULTS:

At baseline, the OKG showed lower functional performance and unilateral balance, and impaired lower-limb loading distribution compared to the OG and the YG (p<0.05). After resistance training, the OKG showed improvements in functional performance (∼13% in sit-to-stand and rising from the floor, ∼16% in stair-climbing and ∼23% in 6-minute walking (6 MW)), unilateral balance (∼72% and ∼78% in TKA and OA leg, respectively) and lower-limb loading distribution, which were greater than those observed in the OG and the YG. The OKG showed post-training 6 MW performance similar to that of the OG at baseline. Sit-to-stand performance and unilateral stand balance were further restored to post-training levels of the OG and to baseline levels of the YG.

CONCLUSIONS:

Resistance training partially restored functional, balance and lower-limb loading deficits in older women with TKA and OA in the contralateral knee. These results suggest that resistance training may be an important tool to counteract mobility impairments commonly found in this population.     

Manual for guided home exercises for osteoarthritis of the knee

INTRODUCTION:

Physiotherapy is one of the most important components of therapy for osteoarthritis of the knee. The objective of this prospective case series was to assess the efficiency of a guidance manual for patients with osteoarthritis of the knee in relation to pain, range of movement , muscle strength and function, active goniometry, manual strength test and function.

METHODS:

Thirty-eight adults with osteoarthritis of the knee (≥ 45 years old) who were referred to the physiotherapy service at the university hospital (Santa Casa de Misericórdia de São Paulo) were studied. Patients received guidance for the practice of specific physical exercises and a manual with instructions on how to perform the exercises at home. They were evaluated for pain, range of movement, muscle strength and function. These evaluations were performed before they received the manual and three months later. Patients were seen monthly regarding improvements in their exercising abilities.

RESULTS:

The program was effective for improving muscle strength, controlling pain, maintaining range of movement of the knee joint, and reducing functional incapacity.

DISCUSSION:

A review of the literature showed that there are numerous clinical benefits to the regular practice of physical therapy exercises by patients with osteoarthritis of the knee(s) in a program with appropriate guidance. This study shows that this guidance can be attained at home with the use of a proper manual.

CONCLUSIONS:

Even when performed at home without constant supervision, the use of the printed manual for orientation makes the exercises for osteoarthritis of the knee beneficial.     

Isokinetic assessment of the hip muscles in patients with osteoarthritis of the knee

OBJECTIVES:

To evaluate the difference in isokinetic strength of hip muscles between patients with knee osteoarthritis (OA) and matched healthy controls, and to establish the correlation between this isokinetic strength and pain and function in patients with knee OA.

METHODS:

25 patients with a diagnosis of unilateral knee OA, 25 patients with bilateral knee OA, and 50 matched controls were evaluated using the visual analog scale for pain, knee Lequesne index, Western Ontario and McMaster Universities questionnaire and an isokinetic test.

RESULTS:

The groups were matched for age, gender and body mass index. The results of the isokinetic test revealed lower peak torque of the hip in patients with OA of the knee than in the control group for all movements studied. Strong correlations were found between the peak torque, visual analog scale and function.

CONCLUSIONS:

Patients with OA of the knee exhibit lower isokinetic strength in the hip muscles than healthy control subjects. Strengthening the muscles surrounding the hip joint may help to decrease pain in people with knee OA. Some correlations between pain/function and peak torque were found.     

Restless legs syndrome in subjects with a knee prosthesis: evidence that symptoms are generated in the periphery

OBJECTIVE:

There are no data adressing the prevalence of restless legs syndrome in subjects who have knee prosthesis. Therefore, we conducted a cross-sectional survey of subjects who underwent knee prosthesis surgery.

METHOD:

A total of 107 subjects (30 male, 77 female) were interviewed over the telephone regarding restless legs syndrome symptoms. If the patients exhibited symptoms of the syndrome, we conducted face-to-face interviews. Lastly, a therapeutic test with pramipexole was proposed for each subject.

RESULTS:

In our cohort, 7 males (23%) and 30 females (39%) had restless legs syndrome. Of these, 6 males and 23 females were submitted to face-to-face-interview. Of the males, 5 (83%) had restless legs after the knee surgery- exclusively in the operated leg- and reported no family restless legs history. One man had a prior case of bilateral restless legs syndrome, a positive family history and claimed exacerbation of symptoms in the operated leg. Among the females, 16 (69%) had restless legs prior to surgery. A total of 10 female patients reported bilateral symptoms, with fewer symptoms in the operated leg, while 6 displayed a worse outcome in the operated leg. The 7 females (31%) without restless legs prior to surgery and without a family history experienced symptoms only in the operated leg. All subjects responded favorably to the pramipexole therapeutic test.

CONCLUSION:

Our results suggest that secondary unilateral restless legs syndrome may ensue from knee prosthesis surgery and that the symptoms are generated in the peripheral nervous system.     

The association of anthropometric measures and osteoarthritis knee in non-obese subjects: a cross sectional study

OBJECTIVE:

Body mass index (BMI) and knee osteoarthritis have a strong association, but other anthropometric measures lack such associations. To date, no study has evaluated non‐obese knee osteoarthritis to negate the systemic and metabolic effects of obesity. This study examines the validity of the contention that BMI and other anthropometric measures have a significant relationship with knee osteoarthritis.

METHODS:

In total, 180 subjects with a diagnosis of knee osteoarthritis were recruited and classified according to Kellgren‐Lawrence (KL) grades. Body mass index, mid‐upper arm circumference, waist‐hip ratio and triceps‐skinfold thickness were recorded by standard procedures. Osteoarthritis outcome scores (WOMAC) were evaluated.

RESULTS:

(1) In both genders, the BMI was significantly higher for KL grade 4 than for grade 2; triceps‐skinfold thickness was positively correlated with the joint space width of the tibial medial compartment. (2) In males, triceps‐skinfold thickness significantly increased as the KL grades moved from 2 to 4; the significantly higher BMI found in varus aligned knees was positively correlated with WOMAC scores. (3) In females, the waist‐hip ratio was significantly higher for KL grade 4 than for grade 2; a significant correlation was found between BMI and WOMAC scores. The waist‐hip ratio was significantly associated with varus aligned knees and it positively correlated with WOMAC scores and with the joint space width of the tibial medial compartment. The mid‐upper arm circumference demonstrated no correlation with knee osteoarthritis.

CONCLUSION:

This study validates the contention that BMI and other anthropometric measures have a significant association with knee osteoarthritis. Contrary to common belief, the triceps‐skinfold thickness (peripheral fat) in males and the waist‐hip ratio (central fat) in females were more strongly associated with knee osteoarthritis than BMI.     

Whole-body vibration and the prevention and treatment of delayed-onset muscle soreness

Context:

Numerous recovery strategies have been used in an attempt to minimize the symptoms of delayed-onset muscle soreness (DOMS). Whole-body vibration (WBV) has been suggested as a viable warm-up for athletes. However, scientific evidence to support the protective effects of WBV training (WBVT) on muscle damage is lacking.

Objective:

To investigate the acute effect of WBVT applied before eccentric exercise in the prevention of DOMS.

Design:

Randomized controlled trial.

Setting:

University laboratory.

Patients or Other Participants:

A total of 32 healthy, untrained volunteers were randomly assigned to either the WBVT (n  =  15) or control (n  =  17) group.

Intervention(s):

Volunteers performed 6 sets of 10 maximal isokinetic (60°/s) eccentric contractions of the dominant-limb knee extensors on a dynamometer. In the WBVT group, the training was applied using a vibratory platform (35 Hz, 5 mm peak to peak) with 100° of knee flexion for 60 seconds before eccentric exercise. No vibration was applied in the control group.

Main Outcome Measure(s):

Muscle soreness, thigh circumference, and pressure pain threshold were recorded at baseline and at 1, 2, 3, 4, 7, and 14 days postexercise. Maximal voluntary isometric and isokinetic knee extensor strength were assessed at baseline, immediately after exercise, and at 1, 2, 7, and 14 days postexercise. Serum creatine kinase was measured at baseline and at 1, 2, and 7 days postexercise.

Results:

The WBVT group showed a reduction in DOMS symptoms in the form of less maximal isometric and isokinetic voluntary strength loss, lower creatine kinase levels, and less pressure pain threshold and muscle soreness (P < .05) compared with the control group. However, no effect on thigh circumference was evident (P < .05).

Conclusions:

Administered before eccentric exercise, WBVT may reduce DOMS via muscle function improvement. Further investigation should be undertaken to ascertain the effectiveness of WBVT in attenuating DOMS in athletes.     

Immunohistochemical analysis of the neural structures of the posterior cruciate ligament in osteoarthritis patients submitted to total knee arthroplasty: an analysis of thirty-four cases

OBJECTIVES:

Many authors recommend posterior cruciate ligament-retaining arthroplasty with the intention to maintain the proprioception properties of this ligament. Preservation of the neuroreceptors and nervous fibers may be essential for retaining the proprioception function of the posterior cruciate ligament. The present study was thus developed to evaluate the presence of neural structures in the posterior cruciate ligament resected during posterior stabilized arthroplasty in osteoarthritis patients. In particular, clinical, radiographic and histological parameters were correlated with the presence or absence of neural structures in the posterior cruciate ligament.

METHODS:

In total, 34 posterior cruciate ligament specimens were stained with hematoxylin-eosin and Gomori trichrome. An immunohistochemical analysis using antibodies against the S100 protein and neurofilaments was also performed. The presence of neural structures was correlated with parameters such as tibiofemoral angulation, histological degeneration of the posterior cruciate ligament, Ahlbäck radiological classification, age, gender and the histologic pattern of the synovial neurovascular bundle around the posterior cruciate ligament.

RESULTS:

In total, 67.5% of the cases presented neural structures in the posterior cruciate ligament. In 65% of the cases, the neurovascular bundle was degenerated. Nervous structures were more commonly detected in varus knees than in valgus knees (77% versus 50%). Additionally, severe histologic degeneration of the posterior cruciate ligament was related to neurovascular bundle degeneration.

CONCLUSIONS:

Severe posterior cruciate ligament degeneration was related to neurovascular bundle compromise. Neural structures were more commonly detected in varus knees. Intrinsic neural structures were detected in the majority of the posterior cruciate ligaments of patients submitted to knee arthroplasty for osteoarthritis.     

The Hip and Knee Book: developing an active management booklet for hip and knee osteoarthritis

Background

The pain and disability of hip and knee osteoarthritis can be improved by exercise, but the best method of encouraging this is not known.

Aim

To develop an evidence-based booklet for patients with hip or knee osteoarthritis, offering information and advice on maintaining activity.

Design of study

Systematic review of reviews and guidelines, then focus groups.

Setting

Four general practices in North East Wales.

Method

Evidence-based messages were developed from a systematic review, synthesised into patient-centred messages, and then incorporated into a narrative. A draft booklet was examined by three focus groups to improve the phrasing of its messages and discuss its usefulness. The final draft was examined in a fourth focus group.

Results

Six evidence-based guidelines and 54 systematic reviews were identified. The focus groups found the draft booklet to be informative and easy to read. They reported a lack of clarity about the cause of osteoarthritis and were surprised that the pain could improve. The value of exercise and weight loss beliefs was accepted and reinforced, but there was a perceived contradiction about heavy physical work being causative, while moderate exercise was beneficial. There was a fear of dependency on analgesia and misinterpretation of the message on hyaluranon injections. The information on joint replacement empowered patients to discuss referral with their GP. The text was revised to accommodate these issues.

Conclusion

The booklet was readable, credible, and useful to end-users. A randomised controlled trial is planned, to test whether the booklet influences beliefs about osteoarthritis and exercise.     

Preliminary analysis of knee stress in Full Extension Landing

OBJECTIVE:

This study provides an experimental and finite element analysis of knee-joint structure during extended-knee landing based on the extracted impact force, and it numerically identifies the contact pressure, stress distribution and possibility of bone-to-bone contact when a subject lands from a safe height.

METHODS:

The impact time and loads were measured via inverse dynamic analysis of free landing without knee flexion from three different heights (25, 50 and 75 cm), using five subjects with an average body mass index of 18.8. Three-dimensional data were developed from computed tomography scans and were reprocessed with modeling software before being imported and analyzed by finite element analysis software. The whole leg was considered to be a fixed middle-hinged structure, while impact loads were applied to the femur in an upward direction.

RESULTS:

Straight landing exerted an enormous amount of pressure on the knee joint as a result of the body''s inability to utilize the lower extremity muscles, thereby maximizing the threat of injury when the load exceeds the height-safety threshold.

CONCLUSIONS:

The researchers conclude that extended-knee landing results in serious deformation of the meniscus and cartilage and increases the risk of bone-to-bone contact and serious knee injury when the load exceeds the threshold safety height. This risk is considerably greater than the risk of injury associated with walking downhill or flexion landing activities.     

Acute strength exercise and the involvement of small or large muscle mass on plasma brain-derived neurotrophic factor levels

OBJECTIVE:

Blood neurotrophins, such as the brain‐derived neurotrophic factor, are considered to be of great importance in mediating the benefits of physical exercise. In this study, the effect of acute strength exercise and the involvement of small versus large muscle mass on the levels of plasma brain‐derived neurotrophic factor were evaluated in healthy individuals.

METHODS:

The concentric strengths of knee (large) and elbow (small) flexor and extensor muscles were measured on two separate days. Venous blood samples were obtained from 16 healthy subjects before and after exercise.

RESULTS:

The levels of brain‐derived neurotrophic factor in the plasma did not significantly increase after both arm and leg exercise. There was no significant difference in the plasma levels of the brain‐derived neurotrophic factor in the arms and legs.

CONCLUSION:

The present results demonstrate that acute strength exercise does not induce significant alterations in the levels of brain‐derived neurotrophic factor plasma concentrations in healthy individuals. Considering that its levels may be affected by various factors, such as exercise, these findings suggest that the type of exercise program may be a decisive factor in altering peripheral brain‐derived neurotrophic factor.     

Clinical and epidemiological differences between septic arthritis of the knee and hip caused by oxacillin-sensitive and -resistant s. aureus

OBJECTIVE:

To establish the risk factors for joint infection by oxacillin-resistant Staphylococcus aureus (MRSA) using clinical and epidemiological data.

METHODS:

All septic arthritis cases of the knee and hip diagnosed and treated in our institution from 2006 to 2012 were evaluated retrospectively. Only patients with cultures identified as microbial agents were included in the study. The clinical and epidemiological characteristics of the patients were analyzed, seeking the differences between populations affected by MRSA and oxacillin-sensitive Staphylococcus aureus (MSSA).

RESULTS:

S. aureus was isolated in thirty-five patients (46.0%) in our total sample, 25 in the knee and 10 in the hip. Of these 35 patients, 22 presented with MSSA and 13 presented with MRSA. Provenance from a health service-related environment, as described by the Centers for Disease Control and Prevention, was the only variable associated with oxacillin-resistant strains of this bacterium (p = 0.001).

CONCLUSION:

Provenance from a health service-related environment was associated with a higher incidence of MRSA-related septic arthritis, suggesting that this agent should be considered in the initial choice of antibiotic treatment. Previous surgeries of the knee or affected limb and the absence of leukocytes might also be related to infection with this agent.     

Effect of postoperative use of nasal oxygen catheter supplementation in wound healing following total knee arthroplasty

OBJECTIVES:

Healing is an event that is fundamental to the success of total knee arthroplasty. The aims of the present study were to compare the rates of complications related to wound healing between two groups of volunteers submitted to total knee arthroplasty and to evaluate the effects of postoperative oxygen supplementation by means of a nasal catheter.

METHOD:

A total of 109 patients who underwent total knee arthroplasty were randomized into two groups, namely, groups that did and did not receive postoperative oxygen supplementation via a nasal catheter. The surgical wound was monitored every day during the hospital stay and on the 7^th, 14^th, 21^st, 30^th and 42^nd postoperative days. Characteristics related to healing were observed, including hyperemia, dehiscence, necrosis, phlyctenules and deep and superficial infection.

RESULTS:

There were no cases of deep infection. Hyperemia was statistically correlated with the total number of complications in the groups, with oxygen demonstrated to be a protective factor against hyperemia. Approximately 30% of the patients who exhibited hyperemia had other complications, independent of oxygen supplementation.

CONCLUSION:

Oxygen supplementation following total knee arthroplasty was shown to be effective in diminishing hyperemia around the operative wound. The development of hyperemia was a precursor to other complications, irrespective of whether oxygen supplementation was used.     

Anteroposterior displacement behavior of the center of pressure,without visual reference,in postmenopausal women with and without lumbar osteoporosis

OBJECTIVE:

The aims of this study were to evaluate the anteroposterior displacement behavior of the center of pressure without any visual reference and determine its relationship with knee muscle strength and reports of falls in postmenopausal women. Among those with osteoporosis, the specific objective was to evaluate the correlation of thoracic kyphosis and vitamin D with center of pressure displacement.

METHODS:

This was a cross-sectional observational study without intervention. The assessments were performed on 126 postmenopausal women (aged 55-65 years) who were grouped according to their lumbar bone density into osteoporosis and control groups. Center of pressure was evaluated on a force platform (100 Hz frequency and 10 Hz filter), with the subjects standing on both feet with eyes closed for 60 seconds. Knee muscle strength was evaluated using an isokinetic dynamometer in concentric/concentric mode at a velocity of 60°/s. In the osteoporosis group, vitamin D was assayed, and the thoracic spine was radiographed.

RESULTS:

In the control group, there was a correlation between the center of pressure and knee strength (r = 0.37; p<0.003). Reports of falls were not associated with center of pressure displacement (p = 0.056). In the osteoporosis group, thoracic kyphosis and vitamin D levels were not correlated with the center of pressure.

CONCLUSION:

Anteroposterior center of pressure displacement without visual influence was not associated with falls, thoracic kyphosis or vitamin D in the osteoporosis group. Only knee muscle strength was associated with center of pressure displacement in the control group.     

The influence of tourniquet use and operative time on the incidence of deep vein thrombosis in total knee arthroplasty

OBJECTIVE:

To evaluate the association between tourniquet and total operative time during total knee arthroplasty and the occurrence of deep vein thrombosis.

METHODS:

Seventy-eight consecutive patients from our institution underwent cemented total knee arthroplasty for degenerative knee disorders. The pneumatic tourniquet time and total operative time were recorded in minutes. Four categories were established for total tourniquet time: <60, 61 to 90, 91 to 120, and >120 minutes. Three categories were defined for operative time: <120, 121 to 150, and >150 minutes. Between 7 and 12 days after surgery, the patients underwent ascending venography to evaluate the presence of distal or proximal deep vein thrombosis. We evaluated the association between the tourniquet time and total operative time and the occurrence of deep vein thrombosis after total knee arthroplasty.

RESULTS:

In total, 33 cases (42.3%) were positive for deep vein thrombosis; 13 (16.7%) cases involved the proximal type. We found no statistically significant difference in tourniquet time or operative time between patients with or without deep vein thrombosis. We did observe a higher frequency of proximal deep vein thrombosis in patients who underwent surgery lasting longer than 120 minutes. The mean total operative time was also higher in patients with proximal deep vein thrombosis. The tourniquet time did not significantly differ in these patients.

CONCLUSION:

We concluded that surgery lasting longer than 120 minutes increases the risk of proximal deep vein thrombosis.     

Symptomatic and Functional Responses to Concentric-Eccentric Isokinetic Versus Eccentric-Only Isotonic Exercise

Context:

Rehabilitation protocols involving eccentric resistance exercise performed with loading more than 100% concentric 1-repetition maximum are effective in increasing muscle function in both healthy and injured populations. The mode of eccentric exercise (isokinetic versus isotonic) may be an important factor in limiting symptoms of delayed-onset muscle soreness and in improving muscle function after training.

Objective:

To compare functional and symptomatic responses after an eccentric-only (ECC) isotonic exercise protocol and after a combined concentric-eccentric (CON-ECC) isokinetic exercise protocol matched for total exercise volume.

Design:

Observational study.

Setting:

Controlled research laboratory.

Patients or Other Participants:

Twenty-four healthy, untrained, college-aged men (n  =  12) and women (n  =  12).

Intervention(s):

Participants were randomly assigned to the ECC isotonic or CON-ECC isokinetic exercise group and performed a single bout of resistance exercise involving the elbow flexors.

Main Outcome Measure(s):

Measurements of elbow flexion and extension, isometric strength, and muscle point tenderness were obtained before exercise (baseline) and during follow-up sessions (days 2, 4, 7, and 14). Separate 1-way analyses of variance and repeated-measures analyses of variance were used to determine outcome differences. Tukey post hoc testing was performed when indicated.

Results:

At baseline, no differences were present between groups for any measure. The ECC isotonic exercise protocol resulted in a 30% to 36% deficit in muscle strength, a 5% to 7% reduction in elbow flexion, and a 6% to 8% reduction in elbow extension at follow-up days 2 and 4 (P < .01). The CON-ECC isokinetic exercise protocol did not alter muscle strength or range of motion at any time when compared with baseline. Muscle point tenderness increased from baseline on days 2 and 4 in both groups (P < .05) but was not different between groups throughout the recovery period.

Conclusions:

Our results indicated more pronounced functional deficits occurred after a single bout of ECC isotonic exercise than with a CON-ECC isokinetic exercise protocol matched for training volume.     

Leg Immersion in Warm Water,Stretch-Shortening Exercise,and Exercise-Induced Muscle Damage

Context:

Whether muscle warming protects against exercise-induced muscle damage is unknown.

Objective:

To determine the effect of leg immersion in warm water before stretch-shortening exercise on the time course of indirect markers of exercise-induced muscle damage.

Design:

Crossover trial.

Setting:

Human kinetics laboratory.

Patients or Other Participants:

Eleven healthy, untrained men (age  =  21.5 ± 1.7 years).

Intervention(s):

Participants'' legs were immersed in a water bath at 44 ± 1°C for 45 minutes.

Main Outcome Measure(s):

Creatine kinase changes in the blood, muscle soreness, prolonged (within 72 hours) impairment in maximal voluntary contraction force and height of drop jump, and electrically evoked muscle force at low and high stimulation frequencies at short and long muscle lengths.

Results:

Leg immersion in warm water before stretch-shortening exercise reduced most of the indirect markers of exercise-induced muscle damage, including creatine kinase activity in the blood, muscle soreness, maximal voluntary contraction force, and jump height. The values for maximal voluntary contraction force and jump height, however, were higher during prewarming than for the control condition at 48 hours after stretch-shortening exercise, but this difference was only minor at other time points. Muscle prewarming did not bring about any changes in the dynamics of low-frequency fatigue, registered at either short or long muscle length, within 72 hours of stretch-shortening exercise.

Conclusions:

Leg immersion in warm water before stretch-shortening exercise reduced most of the indirect markers of exercise-induced muscle damage. However, the clinical application of muscle prewarming may be limited, because decreasing muscle damage did not necessarily lead to improved voluntary performance.     

Contribution of Knee Flexor and Extensor Strength on Sex-Specific Energy Absorption and Torsional Joint Stiffness During Drop Jumping

Context:

Lower extremity injury often occurs during abrupt deceleration when attempting to change the body''s direction. Although sex-specific biomechanics have been implicated in the greater risk of acute knee injury in women than in men, it is unknown if sex differences in thigh strength affect sex-specific energy absorption and torsional joint stiffness patterns.

Objective:

To determine sex differences in energy absorption patterns and joint stiffnesses of the lower extremity during a drop jump and to determine if these sex differences were predicted by knee extensor and flexor strength.

Design:

Cross-sectional study.

Setting:

Laboratory environment.

Patients or Other Participants:

Recreationally active, college-aged students (41 women: age  =  22.1 ± 2.9 years, height  =  1.63 ± 0.07 m, mass  =  59.3 ± 8.0 kg; 40 men: age  =  22.4 ± 2.8 years, height  =  1.77 ± 0.1 m, mass  =  80.9 ± 14.1 kg).

Intervention(s):

Participants performed knee flexor and extensor maximal voluntary isometric contractions followed by double-leg drop-jump landings.

Main Outcome Measure(s):

Lower extremity joint energetics (J × N⁻¹ × m⁻¹) and torsional joint stiffnesses (Nm × N⁻¹ × m⁻¹ × degrees⁻¹) were calculated for the hip, knee, and ankle during the initial landing phase. Body weight was measured in newtons and height was measured in meters. Sex comparisons were made and sex-specific regressions determined if thigh muscle strength (Nm/kg) predicted sagittal-plane landing energetics and stiffnesses.

Results:

Women absorbed 69% more knee energy and had 36% less hip torsional stiffness than men. In women, greater knee extensor strength predicted greater knee energy absorption (R²  =  0.11, P  =  .04), and greater knee flexor strength predicted greater hip torsional stiffness (R²  =  0.12, P  =  .03).

Conclusions:

Sex-specific biomechanics during the deceleration phase of a drop jump revealed that women used a strategy to attempt to decrease system stiffness. Additionally, only female strength values were predictive of landing energetics and stiffnesses. These findings collectively demonstrated that the task may have been more difficult for women, resulting in a different movement strategy among those with different levels of thigh strength to safely complete the task. Future researchers should look at other predictive factors of observed sex differences.     

Scapular-muscle performance: two training programs in adolescent swimmers

Context:

Swimming requires well-balanced scapular-muscle performance. An additional strength-training program for the shoulders is pursued by swimmers, but whether these muscle-training programs need to be generic or specific for endurance or strength is unknown.

Objective:

To evaluate isokinetic scapular-muscle performance in a population of adolescent swimmers and to compare the results of training programs designed for strength or muscle endurance.

Design:

Controlled laboratory study.

Setting:

University human research laboratory.

Patients or Other Participants:

Eighteen adolescent swimmers.

Intervention(s):

Each participant pursued a 12-week scapular-training program designed to improve either muscle strength or muscle endurance.

Main Outcome Measure(s):

Bilateral peak force, fatigue index, and protraction/retraction strength ratios before and after the scapular-training program.

Results:

Scapular protraction/retraction ratios were slightly higher than 1 (dominant side  =  1.08, nondominant side  =  1.25, P  =  .006). Side-to-side differences in retraction strength were apparent both before and after the training program (P  =  .03 and P  = .05, respectively). After the training program, maximal protraction (P < .05) and retraction (P < .01) strength improved on the nondominant side. Peak force and fatigue index were not different between the training groups. The fatigue indexes for protraction on both sides (P < .05) and retraction on the nondominant side (P  =  .009) were higher after the training program.

Conclusions:

We describe the scapular-muscle characteristics of a group of adolescent swimmers. Both muscle-strength and muscle-endurance programs improved absolute muscle strength. Neither of the strength programs had a positive effect on scapular-muscle endurance. Our results may be valuable for coaches and physiotherapists when they are designing exercise programs for swimmers.     

Comparison of Lower Extremity Kinematics and Hip Muscle Activation During Rehabilitation Tasks Between Sexes

Context:

Closed kinetic chain exercises are an integral part of rehabilitation programs after lower extremity injury. Sex differences in lower extremity kinematics have been reported during landing and cutting; however, less is known about sex differences in movement patterns and activation of the hip musculature during common lower extremity rehabilitation exercises.

Objective:

To determine whether lower extremity kinematics and muscle activation levels differ between sexes during closed kinetic chain rehabilitation exercises.

Design:

Cross-sectional with 1 between-subjects factor (sex) and 1 within-subjects factor (exercise).

Setting:

Research laboratory.

Patients or Other Participants:

Participants included 21 women (age  =  23 ± 5.8 years, height  =  167.6 ± 5.1 cm, mass  =  63.7 ± 5.9 kg) and 21 men (age  =  23 ± 4.0 years, height  =  181.4 ± 7.4 cm, mass  =  85.6 ± 16.5 kg).

Intervention(s):

In 1 testing session, participants performed 3 trials each of single-leg squat, lunge, and step-up-and-over exercises.

Main Outcome Measure(s):

We recorded the peak joint angles (degrees) of knee flexion and valgus and hip flexion, extension, adduction, and external rotation for each exercise. We also recorded the electromyographic activity of the gluteus maximus, rectus femoris, adductor longus, and bilateral gluteus medius muscles for the concentric and eccentric phases of each exercise.

Results:

Peak knee flexion angles were smaller and peak hip extension angles were larger for women than for men across all tasks. Peak hip flexion angles during the single-leg squat were smaller for women than for men. Mean root-mean-square amplitudes for the gluteus maximus and rectus femoris muscles in both the concentric and eccentric phases of the 3 exercises were greater for women than for men.

Conclusions:

Sex differences were observed in sagittal-plane movement patterns during the rehabilitation exercises. Because of the sex differences observed in our study, future researchers need to compare the findings for injured participants by sex to garner a better representation of altered kinematic angles and muscle activation levels due to injury.     

Existence of a neuropathic pain component in patients with osteoarthritis of the knee

Purpose

Pain from osteoarthritis (OA) is generally classified as nociceptive (inflammatory). Animal models of knee OA have shown that sensory nerve fibers innervating the knee are significantly damaged with destruction of subchondral bone junction, and induce neuropathic pain (NP). Our objective was to examine NP in the knees of OA patients using painDETECT (an NP questionnaire) and to evaluate the relationship between NP, pain intensity, and stage of OA.

Materials and Methods

Ninety-two knee OA patients were evaluated in this study. Pain scores using Visual Analogue Scales (VAS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), painDETECT, duration of symptoms, severity of OA using the Kellgren-Lawrence (KL) system, and amount of joint fluid were evaluated and compared using a Spearman''s correlation coefficient by rank test.

Results

Our study identified at least 5.4% of our knee OA patients as likely to have NP and 15.2% as possibly having NP. The painDETECT score was significantly correlated with the VAS and WOMAC pain severity. Compared with the painDETECT score, there was a tendency for positive correlation with the KL grade, and tendency for negative correlation with the existence and amount of joint fluid, but these correlations were not significant.

Conclusion

PainDETECT scores classified 5.4% of pain from knee OA as NP. NP tended to be seen in patients with less joint fluid and increased KL grade, both of which corresponded to late stages of OA. It is important to consider the existence of NP in the treatment of knee OA pain.