The effect of knee angle and subject position on plantar flexors isokinetic performance and muscular activity

BACKGROUND: Assessment of the plantar flexion (PF) isokinetic performance has been greatly diverse and based on personal preferences rather than standardized guidelines. OBJECTIVE: To examine the performance of the plantar flexors under different settings including knee joint angle and subject position. METHODS: Thirteen women and 20 men took part in this study. The isokinetic protocol (60∘/s) was set to ankle movement between 10∘ dorsiflexion to 30∘ PF. Participants performed three repetitions of concentric PF in randomly-ordered knee angles; 15∘, 45∘ and 90∘, and in seated and supine positions. Surface electromyography (EMG) data were collected from the Soleus (SOL) and Gastrocnemius. RESULTS: Knee angle impacted the PF moment (P⩽ 0.001–0.026) and work (P⩽ 0.05) measures in both genders. The moment and work measures were significantly less in the 90∘ than those in the 45∘ and 15∘ positions. The 45∘ position had the highest values, particularly in sitting in the male participants. Only the GL EMG data was significantly impacted (P= 0.017) by the subject position. However, the difference was trivial (1.6%). The SOL muscle showed a consistent pattern of increased activity when the knee was in flexion. CONCLUSION: The 45∘ position seems to be optimal for obtaining the highest isokinetic PF scores.

Influence of the medial longitudinal arch of the foot in adult women in ankle isokinetic performance: a cross-sectional study

Background Maintenance of the medial longitudinal arch (MLA) of the foot is fundamental during functional tasks and disorders can lead to clinical alterations. Studies have demonstrated that deficits in ankle isokinetic performance can predispose an individual to lower limb injuries. Objectives To evaluate the muscular performance of cavus, planus, and normal feet by means of torque/body mass and the isokinetic phases, to generate 3D surface map analysis, and to verify whether there is a relationship between MLA height and arch height flexibility with isokinetic performance. Methods The sample consisted of 105 healthy adult women, divided into three groups: normal, cavus, and planus. Assessment in concentric mode at 30, 60, and 90 °/s in the dorsiflexion and plantarflexion of the ankle joint were analyzed during the three isokinetic phases (acceleration, sustained velocity, and deceleration). The variables total range of motion, peak of torque (PT), and angle of PT were extracted within the sustained velocity. Results In dorsiflexion at 60 °/s, the phase where the velocicty is sustained (load range phase) was higher in the planus group (MeanDifference=10.9 %; ω2p = 0.06) when compared with the cavus group. Deficits in the peak torque/body mass in dorsiflexion at 60 °/s (cavus feet: MD=-3 N.m/kg; ω2p = 0.06; and planus feet: MD=-1.1 N.m/kg; ω2p = 0.06) were also observed as well as in the 3D surface maps, when compared with the normal group. The flexibility of MLA had a negative correlation of PT at 30 °/s in cavus group. The heigth of MLA had a postive correlation with the PT for the cavus and planus group ate 60 °/s. All other results did not show differences between the groups. Conclusions The planus groups showed a better capacity of attain and sustained the velocity in dorsiflexion in relation the cavus group. The cavus and planus group had deficts in torque in relation the normal. The correlations were weak between the measures of MLA and PT. Thereby, in general the differences between foot types showed small effect in isokinetic muscle performance measures of the plantar and dorsi flexores. Trial registration Study design was approved by the IRB (#90238618.8.0000.5231).

Isokinetic performance and function are similar after total hip arthroplasty applied with a posterior or anterolateral approach: a randomised controlled trial

Background: There are ongoing debates on the effects of surgical approach on outcome after total hip arthroplasty (THA). It was hypothesised that with the anterolateral approach, trauma to the abductor arm can occur and related detrimental effects can diminish the postoperative outcomes. In this first randomised controlled trial in the literature on this subject, isokinetic performance and patient-reported functional outcomes were evaluated in patients undergoing THA with a posterior approach (PA) and an anterolateral approach (ALA). Methods: A total of 48 patients scheduled to undergo THA were randomised to ALA or PA groups. The patients were evaluated preoperatively and at 6 and 12 months postoperatively, with flexion, extension and abduction strength measurements and the Harris Hip Score (HHS). The physiatrist performing isokinetic tests and the patients were blinded to the study groups. Results: Both groups were similar in respect of age, body mass index (BMI), gender and preoperative isokinetic performance and HHS. Both groups demonstrated similar isokinetic performance ( p < 0.05) and there was no difference in HHS ( p < 0.05) at the 6- and 12-months follow-up evaluations. Conclusion: Although there is concern about potential abductor muscle damaging during ALA, the results of this randomised controlled study demonstrated that ALA can produce similar isokinetic performance and functional outcome to PA at 6 and 12 months, despite the close proximity to the abductor arm. Trial registration number: ClinicalTrials.gov NCT04640740 (retrospectively registered).

Total Infrapatellar Fat Pad Excision Leads to Worse Isokinetic Performance in Total Knee Arthroplasty: A Randomized Controlled Trial

There are concerns that total infrapatellar fat pad (IPFP) excision in total knee arthroplasty (TKA) results in patellar tendon shortening due to ischemic contracture, but individual preference of the surgeon is still the main determinant between total or partial excision. The aim of this randomized controlled study was to compare isokinetic performance and clinical outcome of TKAs with total and partial excision of the IPFP. Seventy-two patients scheduled to undergo TKA for primary knee osteoarthritis by a single surgeon were randomly assigned to either total or partial excision group. Patients were evaluated preoperatively and at postoperative 1 year, with Knee Society Score (KSS) and isokinetic measurements. The physiatrist performing isokinetic tests and patients were blinded to the study. There were no significant differences between the groups in respect of age, body mass index, gender, and preoperative KSS and isokinetic performance. Postoperatively, both groups had improved KSS knee and KSS function scores, with no difference determined. Knee extension peak torque was significantly higher postoperatively in the partial excision group at postoperative 1 year (p = 0.036). However, there were no significant differences in knee flexion peak torque following TKA (p = 0.649). The results of this study demonstrated that total excision of the IPFP during TKA is associated with worse isokinetic performance, which is most likely due to changes in the knee biomechanics with the development of patella baja. Partial excision of the IPFP appears to be a valid alternative to overcome this potential detrimental effect without impeding exposure to the lateral compartment. This is a Level I, therapeutic study.

ISOKINETIC PERFORMANCE AND LIMB ASYMMETRY DIFFERENCES BETWEEN ADOLESCENT MALES AND FEMALES FOLLOWING QUADRICEPS TENDON – PATELLAR BONE AUTOGRAFT ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION

Background: Accurate measurement of limb strength asymmetry differences between sexes may be important to consider when determining readiness to return to sport among adolescents following ACL reconstruction. Hypothesis/Purpose: The purpose was to compare isokinetic performance between females and males after ACL reconstruction but before return to sport clearance on isokinetic measures of limb strength asymmetry and flexor/extensor strength ratio. We hypothesized there would be no difference in limb strength asymmetry or flexor/extensor strength ratio between sexes measured by isokinetic testing. Methods: We retrospectively collected demographic, surgical, and injury information on patients aged 10 – 18 years at time of surgery. Patients completed isokinetic testing within 5-10 months after primary quadriceps tendon ACL reconstruction, and before return to sport clearance. Isokinetic testing assessed maximum torque at three speeds, 60, 180, and 300 degrees per second, through a limited range of knee extension and flexion. Maximum torque percent deficit of the involved leg compared to the uninvolved leg and flexor/extensor strength ratios were calculated. We compared peak torque extensor deficits and flexor deficits (the % difference between operative and non-operative sides) and flexor/extensor ratios at the three isokinetic test speeds within sexes and between sexes. Results: 80 subjects were tested during the study period, of which 44 subjects met inclusion criteria (female: n=29, 66%). Injury characteristics and time since surgery were similar between sexes (Table 1). Greater extensor deficits among males and females were observed at 60 degrees/s compared to 180 degree/s (p=0.003) and 300 degree/s (p<0.001), and at 180 degrees/s compared to 300 degrees/s (p=0.001) (Figure 1). Females demonstrated significantly greater peak torque flexor deficits at 300 degrees/s, compared to males (p=0.04, Figure 2). Within males, greater flexor deficits were observed at 60 degrees/s compared to 180 degrees/s (p<0.001) and 300 degrees/s (p=0.001) (Figure 2). Within females, greater flexor deficits were observed at 60 degrees/s compared to 180 degrees/s (p=0.02, Figure 2). There were no significant interactions or main effects of sex or speed for either the operative or the non-operative limb peak torque flexor/extensor ratio. Conclusion: The results demonstrate greater peak torque flexor deficits among females compared to males at the fastest testing speed in our protocol. Currently, our results indicate variability both within and between sex isokinetic performance at different speeds and suggest that isokinetic testing at slower speeds may be most effective in determining strength deficits between limbs. Tables and Figures: [Table: see text][Figure: see text][Figure: see text]