Reviewed by Tyler Tice, PT, DPT, OCS, ATC

After ACL reconstruction surgery, the quadriceps muscle is commonly about 20% weaker on the surgical side than the healthy side. Recent evidence states that changes in the central nervous system can account for some of these deficits, which is why ACL rehabilitation plans need to also include strategies that address these central neural mechanisms and in turn reduce strength loss. Cross education is one such way to do this. Cross Education (CE) is the strength gain found when a patient performs a strengthening exercise program on the uninjured limb to maintain or even gain strength in the injured limb. This can be an effective strategy when a patient’s injury requires complete immobilization or has limited motion due to the recency of the injury. CE can induce structural and functional changes in the patient’s nervous system which increases their ability to activate the quadriceps muscle and thus increase its strength.

Methods:

This systematic review included 7 randomized control trials that met these specific criteria:

• Patients > 18 years old after arthroscopic ACL reconstruction
• Interventions used included unilateral strength, motor control, and balance training to the uninjured limb
• Plans utilized standard protocols of rehabilitation for ACL
• Strength testing was performed on quadriceps and hamstring muscles
• Study was a randomized control trial or controlled clinical trial.

Individuals with other ligamentous injuries of the knee were excluded from this study. Each utilized a variety of training frequencies (2,3, or 5 times per week) and for varying total weeks of training time with 8, 24, 26 weeks total being most common. Several different measures were used among each of the studies to determine the effects of the CE through unilateral training including maximal voluntary isometric contractions (MVICs) of the quadriceps, self-reported knee function, and limb symmetry index (LSI) which is a ratio of the estimated performance of the involved limb and uninvolved limb.

Conclusions of the Study:

All the studies demonstrated a significant difference in quadriceps MVIC between participants who performed standard rehabilitation and unilateral training versus standard rehabilitation alone. The self-reported knee function measures were mostly inconclusive among all the studies, but one that determined at 8 weeks of rehabilitation there was a significant difference in knee function according to the participants suggesting a potential short term benefit to the CE. The LSI scores in studies that extended to the 24 and 26 week time frames demonstrated significant difference between groups who performed the unilateral training and standard rehabilitation and those who did not perform unilateral training. However, this measure is simply and estimation and can be significantly overestimate the functional abilities of an ACL patient at 6 months post-operation. The results of the study concluded that by including unilateral training in the participant’s rehabilitation program, the loss of strength typically experienced by the patients after an ACL reconstruction was reduced by 8.52%. This same effect has been even higher in other types of patients like those with osteoarthritis, multiple sclerosis, or other limb immobilizations and therefore would be an excellent addition for most ACL reconstruction patients.

Clinical Implications:

Through stimulating the nervous system and activating the spinal nerve pathways that contribute to movement of the uninvolved limb, ACL reconstruction patients could experience a protective effect to atrophy and strength loss of the quadricep muscle on the affected side by performing unilateral training of the uninvolved limb. PTs should include this in all stages of rehabilitation, but especially in the early stages when the patient is immobilized or has restricted motion due to surgical protocols. Exercises like the single leg squats or long arc quads that require high degrees of quadriceps activation could be great options to promote this protective effect, as long as it fits within the parameters of the patient’s surgical protocol.

References:

Cuyul-Vásquez, I., Álvarez, E., Riquelme, A., Zimmermann, R., & Araya-Quintanilla, F. (2022). Effectiveness of unilateral training of the uninjured limb on muscle strength and knee function of patients with Anterior Cruciate Ligament Reconstruction: A systematic review and meta-analysis of cross-education. Journal of Sport Rehabilitation, 31(5), 605–616. https://doi.org/10.1123/jsr.2021-0204

Reviewed by Tyler Tice, PT, DPT, OCS, ATC

Introduction:

Ankle sprains are one of the most common injuries in athletes and often leave residual effects on postural control post-injury due to the sensorimotor dysfunction. The Y-balance test is a dynamic balance test that is often utilized to assess these patient’s abilities to demonstrate sufficient dynamic postural control to return to sport or other recreational activities safely after ankle injuries. The maximal reach distance (MRD) in the posteromedial direction of the Y-balance test (PM-YBT) is often used to distinguish individuals with ankle instability from healthy people. Sensory processing and the motor output both have an effect on postural control in performance of the PM-YBT, but the amount each contributes is yet to be determined. This study investigated the contribution of eccentric dorsiflexion and plantarflexion torque control on MRD in the PM-YBT performance and therefore determine its contribution to dynamic postural control.

Methods:

            This was a cross-sectional study with 12 subjects. Exclusion criteria for subject selection included a history of lower extremity surgery, injuries in the previous 6 months, or neurological diseases with balance impairments. Subjects height (cm), weight (Kg), and limb length of dominant limb that were used for kicking a ball (cm) were taken. Subjects performed the PM direction of the YBT using the Move2Perform YBT kit with several practice attempts prior to testing. The patients also performed a 5-second maximal voluntary isometric contraction (MVIC) of plantarflexion and dorsiflexion and torque control testing of the ankle using a Biodex dynamometer system. The torque control was defined as the ability to match eccentric torque output to a target torque level. The subjects were instructed to eccentrically contract the plantar flexors at 50% of MVIC as the dynamometer moved them into dorsiflexion and contract the dorsiflexors eccentrically at 30% MVIC while being moved into plantarflexion. EMG data was also collected for tibialis anterior and the soleus as representatives to compare activation of the plantar flexors and dorsiflexors during this testing.

Conclusions of the Study:

            Statistical analysis revealed a higher torque control during eccentric dorsiflexion predicted higher MRD scores for the participants, however, higher eccentric plantarflexion torque control was not predictive for MRD performance. This is contrary to previous studies, but is likely attributable to methodological differences between the use of the Biodex compared to use of a handheld dynamometer. It was also noted higher tibialis anterior activity during the YBT test also predicted greater accuracy of torque control in the subjects, while higher soleus activity did not. Therefore, eccentric dorsiflexion torque control can be a potential predictive indicator for performance in PM-YBT. It was theorized that the lack of predictability from the plantar flexors eccentric control performance was due to it their primary usage being in single plane of motion while the dorsiflexors have greater impact on multiple planes at a time. Previous EMG data has indicated plantar flexors are activated similarly between healthy individuals and people with ankle instability, while the tibialis anterior was activated less in patients with ankle instability, continuing to support the need for strong dorsiflexors. There needs to be further investigation to confirm the data seen here, since this study was self-limited by the small sample size used.

Clinical Implications:

            This article highlights the importance of ensuring patients have sufficient eccentric dorsiflexor torque control. It seems having better motor control within the tibialis anterior and the other dorsiflexors through direct training can assist in improving the patient’s postural control before returning to recreational activities. The application of this data should not be limited to just athletes or other younger adults who are commonly assessed using the YBT. Although older adults may not be able to perform the PM-YBT, improving the eccentric control of the dorsiflexors may be an effective method for improving older adult’s dynamic balance as well, and consequently reduce their fall risk. Unless the patient has high irritability and cannot tolerate the movement or has precautions surrounding performing active dorsiflexion it would be ideal to begin strengthening this muscle group early to aid in their dynamic balance later in treatment.

References:

Nozu, S., Johnson, K. A., Tanaka, T., Inoue, M., Nishio, H., & Takazawa, Y. (2023). The accuracy of ankle eccentric torque control explains dynamic postural control during the Y-balance test. International Journal of Sports Physical Therapy, 18(5). https://doi.org/10.26603/001c.87760

With the majority of low back pain stemming from idiopathic origin, the condition commonly engulfs a large percentage of rehab cases. In individuals with low back pain, proprioception (aka, the awareness of one’s body position in space) plays a key role in posture and balance control, with decreased control likely contributing to these episodes of pain. Core stabilization exercises that include activation of deeper muscles like the transversus abdominis and lumbar multifidus are utilized as a form of therapeutic exercise to supply the spine with adequate stability. Strengthening exercises for the superficial trunk musculature also aid in the stability of the spine. The randomized control trial conducted by Hlaing et al. (2021) aimed to measure these two parameters, core stabilization and strengthening exercises, on the effects of the factors that are often lacking in individuals with subacute non-specific low back pain, namely: proprioception, balance, and muscle thickness.

The inclusion criteria for this trial consisted of individuals ages 20-50, with subacute nonspecific low back pain of 6-12 weeks, and pain of 3-7/10 on the Visual Analog Scale with a score of 19% or greater on the Modified Oswestry Disability Index. 36 individuals were evenly split into groups performing core stabilization exercises or strengthening exercises and completed these programs for 30 minutes, three times a week, for four weeks. For the participants in the core stabilization group, the muscles were isolated utilizing a drawing in maneuver, with a biofeedback device and manual palpation used to ensure successful contraction. The core stabilization group progressed throughout the weeks to include co-contractions of the transversus abdominis and lumbar multifidus with upper and lower body movements, advancing from sitting to supine to quadruped to ultimately a standing position. For the participants in the strengthening exercise group, the program consisted of progressing exercises centered around spinal flexion and extension to target the abdominal and back musculature respectively, while also working the oblique muscles with side-lying leg raises.

Follow up metrics were examined following the scheduled programs, and proprioception was measured through joint repositioning, with balance analyzed using the Romberg Test and muscle thickness calculated with ultrasound imaging. The results of this study overall demonstrated significant improvements in proprioception, balance, muscle thickness and reductions in pain within both experimental groups. Compared to the strengthening exercise group, the core stabilization group displayed superior improvements in proprioception, balance, and muscle thickness. The participants that underwent core stabilization also exhibited greater reductions in their fear of movement and functional disability scores compared to the strengthening group.

Clinical Bottom Line:

The results of this trial serve as evidence that the inclusion of exercises targeting deep abdominal and spinal muscles, like the transversus abdominis and lumbar multifidus, should not be neglected when treating individuals with subacute nonspecific low back pain. The addition of core stabilization exercises, compared to a sole focus on strength, can contribute to a more holistic rehab approach. Low back pain is often a debilitating condition contributing to fear avoidance and altered compensatory movements, and the transversus abdominis and lumbar multifidus can serve as potent protectors of allowing patients to return to their prior level of function with confidence in their body’s ability to thrive.

 References:

Hlaing SS, Puntumetakul R, Khine EE, Boucaut R. Effects of core stabilization exercise and strengthening exercise on proprioception, balance, muscle thickness and pain related outcomes in patients with subacute nonspecific low back pain: a randomized controlled trial. BMC Musculoskelet Disord. 2021;22(1):998. Published 2021 Nov 30. doi:10.1186/s12891-021-04858-6

Reviewed by Tyler Tice, PT, DPT, OCS, ATC

Balance is most generally defined as the ability to properly maintain postural control and adapt to various environmental stimuli through the interaction of sensory, motor, and cognitive systems. The three components of balance comprise of the visual system, the vestibular system, and the proprioceptive system. Dysregulation in any of these three systems can result in an increased propensity for falling. It is known that imbalance commonly occurs under dual-task conditions among older adults since cognitive function decreases with aging.

Dual-task training refers to the ability to perform both cognitive tasks and physical activities simultaneously. Due to the fact that both cognitive function and physical function steadily decrease as we age, dual task performance can deteriorate, resulting in falls in older adults when they perform activities of daily living that require maintaining balance. Numerous evidence-based studies have examined the effects of dual-task training on improving balance and reducing fall risks in high-risk older adults, such as individuals with Parkinson’s disease or post-stroke. However, few studies have analyzed the impact of dual-task training on both static and dynamic balance in older adults. Therefore, the aim of this study was to investigate the effects of dual-task training on static balance, dynamic balance, and executive function in older adults with a history of falls.

58 older adults were selected from local senior centers and randomly assigned into either the experimental group or the control group. There were numerous inclusion criteria for these participants: over 65 years of age, experienced falls in the last six months, and those who ambulate independently without any assistive devices. All subjects carried out a 45 min training session, twice a week for 6 weeks, and they only received the training program which was assigned to each group.

In the control group (n=29 participants), subjects conducted the balance training program focusing on body stability, body stability combined with hand manipulation, body transport, and body transport combined with hand manipulation. In the experimental group (n=29 participants), subjects were instructed in dual-task training. These subjects in the experimental group practiced balance tasks while simultaneously conducting cognitive tasks, and were asked to maintain attention to both balance and cognitive tasks at all times. Subjects in both groups completed a total of 12 sessions.

There were numerous outcome measurements utilized in this study. The One Leg Standing Test (OLST) was utilized to assess static balance where a participant places their hands on their hips and raises one leg from the floor with their eyes closed. To assess dynamic balance, the Timed Up and Go (TUG) test was performed where a participant rises from a chair and makes a round trip of 3 meters to sit back in the chair. Lastly, executive function was examined through the Trail-Making Test (TMT-B) .

The findings of this study showed that subjects in the experimental group achieved greater improvements in both static and dynamic balance compared to subjects in the control group. Therefore, the results of this study may indicate that dual-task training might be more effective in improving balance than the more traditionally-utilized functional balance training. Older adults require more attentional resources to maintain balance to compensate for decreases in sensory integration, suggesting cognitive components contribute monumentally to maintaining balance.

Clinical Application:

Dual-task training is clinically beneficial to improving static and dynamic balance, as well as executive function in older adults with a history of falls. Additionally, executive function, or the ability to facilitate higher-level cognitive skills, should be considered a major component in balance training for older adults. Below is a graphic of the protocol for the group with dual-task training:

Reference:

Park JH. Is Dual-Task Training Clinically Beneficial to Improve Balance and Executive Function in Community-Dwelling Older Adults with a History of Falls?. Int J Environ Res Public Health. 2022;19(16):10198.

Reviewed by Tyler Tice, PT, DPT, OCS, ATC

Partial-thickness rotator cuff tears (PTRCTs) are very common shoulder-related musculoskeletal injuries, especially in the middle-aged patient population, that can detrimentally impact activities of daily living and result in increased pain levels or functional impairment. Generally, PTRCTs are more painful than full-thickness rotator cuff tears (FTRCTs) and account for a higher proportion of rotator cuff tears. However, many aspects concerning the most effective management of PTRCTs are still controversial in the available scientific literature. This controversy is due to the numerous intrinsic and extrinsic factors that contribute to an individual cuff lesion and prognosis of  PTRCTs for each patient.

The aim of this randomized controlled trial was to investigate the ideal timeline for surgical intervention for patients with PTRCTs. There is a very generalized concern that the size of a partial-thickness rotator cuff tear may increase over time for patients if surgical intervention is considerably delayed. Similarly, it is clearly established in the evidence-based literature that there is no spontaneous healing of PTRCTs without surgical treatment. Researchers in this clinical study were interested in whether immediate surgical treatment of PTRCTs would result in better outcomes compared with delayed surgical treatments after nonoperative treatment. These researchers hypothesized that 6 months of preoperative nonoperative treatment would result in better clinical outcomes than immediate surgical repair for PTRCTs.

78 total patients with PTRCTs were enrolled into this randomized controlled trial. Patients were included in the study if their proportion of torn tendon thickness was greater than 50% and experienced less than 3 months of symptom duration. These patients with PTRCTs were then allocated into two treatment groups through computer-generated randomization: an immediate arthroscopic rotator cuff repair surgery group within 1 week of diagnosis (Group 1), and a group that received 6 months of conservative, nonoperative treatment prior to surgery (Group 2). The non-operative treatment group included instructions on activity modification, NSAIDs, corticosteroid injections into the shoulder joint, and physical therapy.

Following the arthroscopic rotator cuff repair surgeries, the same standardized postoperative rehabilitation protocols were applied to both groups. Each patient wore an abduction brace for the shoulder for 1 month after the operation. Following one month post-operation, pulley exercises were then prescribed to increase forward flexion active range of motion of the shoulder. The patient could then be progressed to isometric exercises in all planes of shoulder motion once passive range of motion was restored to 90%. Outcome measures evaluated at 3 months, 6 months, 12 months, and 24 months included: ASES scores for overall shoulder functional ability, VAS scores for pain levels, and active range of motion in the shoulder (forward flexion, external rotation at side, external rotation at 90 degrees of abduction).

The results of the randomized controlled trial were that both groups showed significant improvements in terms of functional scores and pain VAS scores compared with the initial period. However, at 6 months postoperatively, the group 2 patients (6 months of nonoperative treatment) showed significantly lower pain VAS score and higher ASES Scores than group 1 patients (immediate rotator cuff repair surgery). There were no significant differences between the 2 groups in ROM or functional outcomes at the 24-month follow-up mark.

Clinical Application:

Both immediate surgical repair and delayed repair after nonoperative care were effective in improving clinical outcomes of patients with PTRCTs. Immediate surgical repair is not clinically crucial for the treatment of patients with PTRCTs and a trial of preoperative conservative management may be warranted for patients that have symptomatic PTRCTs.

 References:

Kim Y-S, Lee H-J, Kim J-H, Noh D-Y. When Should We Repair Partial-Thickness Rotator Cuff Tears? Outcome Comparison Between Immediate Surgical Repair Versus Delayed Repair After 6-Month Period of Nonsurgical Treatment. The American Journal of Sports Medicine. 2018;46(5):1091-1096.