The Concurrent Validity and Reliability of Single Leg Squat Among Physically Active Females with and without Dynamic Knee Valgus.

Background: The single leg squat (SLS) motion imitates various maneuvers in sports. It is commonly used as a functional test for the lower limb. SLS with two-dimensional (2-D) video analysis is regularly performed in the clinical setting to assess dynamic knee valgus (DKV). However, 2-D video analysis may not be able to demonstrate the same level of accuracy as three-dimensional (3-D) motion analysis. Purpose: This study aimed to determine the within- and between-day reliability as well as the concurrent validity of 2-D and 3-D motion analysis of lower limb kinematics during 45° and 60° SLS among physically active females with and without DKV. Study Design: Cross-sectional study. Methods: A total of 34 physically active females (17 individuals with excessive DKV and 17 without DKV) participated in the study. Their DKV was determined based on the cut-off values of knee frontal plane projection angle during drop landing. Their lower limb kinematics during SLS at 45° and 60° knee flexion were captured simultaneously by digital cameras (2-D motion capture) and infrared cameras (3-D motion capture). Intraclass Correlation Coefficient (ICC) was used as an indicator for within- and between-day reliability tests of both groups. Bland-Altman Plot and Pearson correlation were used to examine the validity of 2-D and 3-D motion capture methods in evaluating knee valgus angle. Results: Two-dimensional knee FPPA and 3-D knee angle measured during 45° and 60° SLS in normal and excessive DKV groups showed moderate to excellent within-day and between-day reliability (ICC≥ 0.50). The current study showed that the 2-D knee frontal plane projection angle (FPPA) during 45° SLS were valid for the non-dominant leg in both groups. Additionally, the 2-D knee FPPA during 60° SLS were valid for non-dominant leg in excessive DKV group and dominant leg in normal group. Conclusion: Two-dimensional knee FPPA during 45° and 60° SLS also showed high within-and between-day reliability for both groups. The validity of 2-D knee FPPA during SLS depends on the squat depth, stance leg, and presence of DKV. Level of Evidence: 2B.

Comparison of the open kinetic chain and closed kinetic chain strengthening exercises on pain perception and lower limb biomechanics of patients with mild knee osteoarthritis: a randomized controlled trial protocol.

BACKGROUND: Clinical recommendations suggest exercises as the main treatment modality for patients with knee osteoarthritis (OA). This study aimed to compare the effects of two different exercise interventions, i.e., open kinetic chain (OKC) and closed kinetic chain (CKC) exercises, on the pain and lower limb biomechanics of patients with mild knee OA. METHOD: A total of 66 individuals with painful early knee OA, aged 50 years and above, with body mass index (BMI) between 18.9kg/m2 and 29.9 kg/m2 in Kelantan, Malaysia, will be recruited in this study. Participants will be randomly allocated into three different groups, either the OKC, CKC, or control groups. All three groups will attend an individual session with a physiotherapist. The participants in the OKC and CKC groups will perform the exercises three times weekly for 8 weeks at their home. The control group will receive education about clinical manifestations, risk factors, diagnosis, treatment, and nursing care for knee via printed materials. The primary outcomes include self-reported pain scores (visual analog scale), disability scores (Western Ontario and McMaster Universities Arthritis Index), and quality of life scores (Osteoarthritis Knee and Hip Quality of Life). Secondary outcomes include lower limb biomechanics during gait and sit-to-stand as well as isokinetic knee strength. The outcomes will be measured before and after the intervention. DISCUSSION: The present study will compare the effects of two different home-based exercise intervention programs among patients with mild knee OA. The study findings will provide vital information that can be used to design an effective exercise program that aims at delaying the OA progression. TRIAL REGISTRATION: The protocol was registered on 22 December 2020 at ClinicalTrials.gov (registration number: NCT04678609 ).

The effects of hip- and ankle-focused exercise intervention on lower limb mechanics during single leg squat among physically active females.

OBJECTIVES: There are two types of kinetic chain in dynamic knee valgus (DKV) namely top-down (proximal origins) and bottom-up (distal origins). This study compared the influence of four-week hip- and ankle-focused exercises on lower limb mechanics during single-leg squat (SLS) among physically active females. METHODS: Thirty-six physically active females with excessive DKV were divided into either HIP, ANKLE, or control groups. The intervention groups completed exercises that focused either on the hip or ankle musculature for 12 sessions over four weeks. The SLS test protocol was performed with 3D motion capture at pre- and post-intervention. Data were analyzed with two-way ANOVA test. RESULTS: HIP group showed increased dominant knee (F (2.66) = 9.437, P = .001) and ankle (F(2.66) = 16.465, P = .001) sagittal moment during 45° SLS at post-intervention compared to ANKLE and Control groups. HIP group also showed increased hip flexion angle for dominant (F(2.66) = 12.032, P = .001) and non-dominant leg (F(2.66) = 3.618, P = .032) compared to other groups during 60° SLS. No other significant differences were observed on other variables. CONCLUSION: DKV did not show any significant changes during SLS after a four-week exercise intervention focusing on hip and ankle joints.

The effects of hip- and ankle-focused exercise intervention on dynamic knee valgus: a systematic review.

BACKGROUND: A range of non-contact injuries such as anterior cruciate ligament tear, and patellofemoral pain syndrome are caused by disordered knee joint loading from excessive dynamic knee valgus (DKV). Previous systematic reviews showed that DKV could be modified through the influence of hip strength and ankle range of motion. Therefore, the purpose of this systematic review was to examine the effects of exercise intervention which involved either top-down or bottom-up kinetic chains on minimizing DKV in male and female adults and adolescents, with and without existing knee pain. METHODOLOGY: Electronic searches were conducted in SAGE, Science Direct, SCOPUS, and Pubmed. The search strategy consisted of medical subject headings and free-text search keywords, synonyms and variations of 'exercise intervention,' 'knee alignment,' 'dynamic knee valgus', 'knee abduction' that were merged via the Boolean operator 'AND' and 'OR'. The search was conducted on full-text journals that documented the impact of the exercise intervention program involving either the bottom-up or top-down DKV mechanism on the knee kinematics. Furthermore, exercise intervention in this review should last at least one week which included two or three sessions per week. This review also considered both men and women of all ages with a healthy or symptomatic knee problem. The risk of bias of the included studies was assessed by Cochrane risk assessment tool. The protocol of this review was registered at PROSPERO (registration number: CRD42021219121). RESULTS: Ten studies with a total of 423 participants (male = 22.7%, female = 77.3%; adults = 249, adolescents = 123; pre-adolescent = 51) met the inclusion criteria of this review. Seven studies showed the significant effects of the exercise intervention program (range from two weeks to ten weeks) on reducing DKV. The exercise training in these seven studies focused on muscle groups directly attached to the knee joint such as hamstrings and gastrocnemius. The remaining three studies did not show significant improvement in DKV after the exercise intervention (range between eight weeks to twelve weeks) probably because they focused on trunk and back muscles instead of muscles crossing the knee joint. CONCLUSION: Exercises targeting specific knee-joint muscles, either from top-down or bottom-up kinetic chain, are likely to reduce DKV formation. These results may assist athletes and coaches to develop effective exercise program that could minimize DKV and ultimately prevent lower limb injuries.

Bottom-Up Kinetic Chain in Drop Landing among University Athletes with Normal Dynamic Knee Valgus.

The study investigated the influence of ankle strength and its range of motion (ROM) on knee kinematics during drop landing. Fifteen male and fifteen female university athletes with a normal range of dynamic knee valgus (DKV) (knee frontal plane projection angle: men = 3° to 8°, females = 7° to 13°) were recruited. They performed drop landing at height 30 cm and 45 cm with three-dimensional motion capture and analysis. Knee angles were compared at specific landing phases. Isokinetic ankle strength was tested at 60°/s angular velocity while the weight-bearing lunge test was conducted to evaluate ankle ROM. For males, strength for both plantarflexors and dorsiflexors were associated with knee kinematics at both heights (30 cm: r = -0.50, p = 0.03; 45 cm: r = -0.45, p = 0.05) during maximum vertical ground reaction force (MVGRF) phase. For females, ankle invertor strength and knee kinematics were associated at both 30cm (r = 0.53; p = 0.02,) and 45 cm landing heights (r = 0.49, p = 0.03), while plantarflexor strength and knee kinematics showed a significant association during initial contact (r = 0.70, p < 0.01) and MVGRF (r = 0.55, p = 0.02) phases at height 30 cm only. Male and female athletes with normal range of DKV showed a significant relationship between ankle strength and knee kinematics at specific landing phases. These relationships varied with increased landing height.