Weight-bearing Knee Extension Research Articles

Quantitative kinetic and kinematic gait variables after percutaneous achilles tendon repair: Indications for rehabilitation

s / Gait & Posture 37 (2013) S1–S31 S5 ion are lack of foot posture, i.e. lack of support reaction, weakness of plantarflexors, especially of the soleus, and excessive length of triceps surae (post-surgical, post-toxin o due to structural failure). The excessive length of triceps surae affects the plantar flexion — knee extension mechanism to extend the knee, which may result in quadriceps failure and finally in crouch gait with high fatigue. Methods: We selected three children with type-2 diplegia and with the following clinical and instrumental (gait-analysis) charac- teristics: delay of heel-off in terminal stance, absence of push-off; reduced speed with shorter steps, reduced knee extension under load, resulting in crouch gait due to impairment of the foot plan- tar flexion and knee extension mmechanism. Segmental analysis: reduced activity of the triceps surae (M1/5), normal passive ankle ROM, absent active ankle ROM in plantarflexion, inability to raise on the toes. Orthoses used: Anti-talus AFOs from cast, in Estruse. The patients underwent surgical shortening of the Achilles tendon; one with bilateral procedure and two with unilateral procedure. The surgical technique consists in a full cut of the Achilles ten- don approximately in the middle. Both edges are then overlapped and grasped with heavy sutures, keeping the ankle in a 20◦ plan- tar flexion [2]. Post-surgical treatment consists of a lower leg cast in equinus without weight bearing for 6 weeks. Weight bearing is resumed with a second walking cast made at 90◦, to be worn for 4 weeks, followed by AFO. Results: We reviewed the patients 6 months after the surgi- cal procedure. Post-surgical gait-analysis (after 6 months) did not show significant differences from pre-surgical assessment con- cerning foot progression, delayed heel lift in terminal stance and weight-bearing knee extension deficit. The only difference was an increased gait speed and length. The activity of the triceps surae (M3/5) had recovered clinically, the active ROM in plantar flexion was improved, as was the ability to raise on the toes with support. As a consequence, anti-talus AFOs were abandoned. Discussion: The literature describes various surgical techniques whichmay be used to shorten the Achilles tendon. These make use of the same procedures suggested for a traumatic tendon lesion of a previously normal muscle. We know that in CP muscles can be spastic andweak at the same time, and that surgical procedures can alsobe influencedby the tenodenic effect. Aperiodof only6months was probably insufficient to highlight significant changes between pre-surgical and post-surgical gait-analysis. We could nonetheless assess a clinical and functional improvement highlighted by an increased active ROM in plantar flexion and abandonment of AFOs.

Knee-Extension Exercise’s Lack of Immediate Effect on Maximal Voluntary Quadriceps Torque and Activation in Individuals With Anterior Knee Pain

Weight-bearing (WB) and non-weight-bearing (NWB) exercises are commonly used in rehabilitation programs for patients with anterior knee pain (AKP). To determine the immediate effects of isolated WB or NWB knee-extension exercises on quadriceps torque output and activation in individuals with AKP. A single-blind randomized controlled trial. Laboratory. 30 subjects with self-reported AKP. Subjects performed a maximal voluntary isometric contraction (MVIC) of the quadriceps (knee at 90°). Maximal voluntary quadriceps activation was quantified using the central activation ratio (CAR): CAR = MVIC/(MVIC + superimposed burst torque). After baseline testing, subjects were randomized to 1 of 3 intervention groups: WB knee extension, NWB knee extension, or control. WB knee-extension exercise was performed as a sling-based exercise, and NWB knee-extension exercise was performed on the Biodex dynamometer. Exercises were performed in 3 sets of 5 repetitions at approximately 55% MVIC. Measurements were obtained at 4 times: baseline and immediately and 15 and 30 min postexercise. Quadriceps torque output (MVIC: N·m/Kg) and quadriceps activation (CAR). No significant differences in the maximal voluntary quadriceps torque output (F2,27 = 0.592, P = .56) or activation (F2,27 = 0.069, P = .93) were observed among the 3 treatment groups. WB and NWB knee-extension exercises did not acutely change quadriceps torque output or activation. It may be necessary to perform exercises over a number of sessions and incorporate other disinhibitory interventions (eg, cryotherapy) to observe acute changes in quadriceps torque and activation.

Will early reconstruction prevent abnormal kinematics after ACL injury? Two-year follow-up using dynamic radiostereometry in 14 patients operated with hamstring autografts

Previous studies have reported that Anterior Cruciate Ligament (ACL) reconstruction does not restore normal tibial rotation in patients with chronic instability and repeated episodes of giving way. We hypothesised that early ACL reconstruction, using quadruple hamstring autografts, before the pivoting episodes had occurred, would protect the knee joint from developing abnormal kinematics with increased external tibial rotation during flexion. Fourteen consecutive patients (8 men, 6 women) with a median age of 24years (18-43), with a complete, isolated unilateral ACL rupture and an intact contralateral knee, were studied. The operations were performed by one experienced surgeon, using quadruple hamstring autografts. We used dynamic radiostereometry (RSA) with tantalum markers inserted in both the injured and the intact contralateral knee to study the pattern of knee motion during active and weight-bearing knee extension. The patients were evaluated pre-operatively and followed for 2years after the ACL reconstruction. The anterior-posterior laxity was measured using the KT-1000. Before surgical repair of the ACL, the internal/external tibial rotation or abduction/adduction did not differ significantly between the injured and intact knees (P=0.27-0.91). Separate studies of the anterior-posterior translation of the medial and lateral femoral flexion facet centres (MFC and LFC) relative to a fixed tibia did not reveal any significant differences between the injured and intact knees (P=0.21-0.59). Pre-operatively, the KT-1000 laxity measurements showed a side-to-side difference of 2.5 (1.0-5.5) mm. At 2years, the laxity side-to-side difference was 0.5 (0-3.0) mm (P=0.001), and there were still no significant differences between the injured and intact knees in terms of internal/external tibial rotation and abduction/adduction (P=0.13-0.60). Nor did the anterior-posterior translation of the flexion facet centres differs (P=0.27-0.97). During the first 6-8weeks after the ACL injury, before pivoting episodes had occurred, the kinematics of the injured knee were normal and did not differ from those of the intact contralateral knee. Reconstruction of the ACL within 10weeks after injury using quadruple hamstring autografts resulted in unchanged knee kinematics for 2years and no difference compared with the intact contralateral knee. Surgical repair during the early phase after the injury appears to protect the knee from developing abnormal knee motion after an ACL rupture. III.

Footballer's Lateral Meniscus: Anterior Horn Tears of the Lateral Meniscus with a Stable Knee

This paper aimed to identify the characteristics of isolated anterior horn tear of the lateral meniscus in footballers who underwent arthroscopic surgery. We identified 8 patients with stable knee and no ligament injury, who had only isolated anterior horn tear of the lateral meniscus between 2007 and 2009. All 8 patients were footballers, comprising 7 men and 1 woman with mean age of 18.6 years. Arthroscopy revealed multiple longitudinal tears in 2 patients, longitudinal tear in 2 patients, degenerative tear in 3 patients, and flap tear in 1 patient. Two patients were treated by repair, five by partial excision, and one by rasping only. The mean Lysholm score was 65 before surgery and recovered to 89 at the last followup, on average 12 months after surgery. Anterior horn tear of the lateral meniscus in footballers with a stable knee is characterized by pain at the anterolateral aspect of the knee during knee extension, especially when kicking a ball, and pain during weight-bearing knee extension, together with MRI finding of hyperintense signal in the anterior horn of the lateral meniscus. Preoperative diagnosis may be possible based on these findings in footballers.

Differences in patellofemoral kinematics between weight‐bearing and non‐weight‐bearing conditions in patients with patellofemoral pain

Patellar maltracking is thought to be one source of patellofemoral pain. Measurements of patellar tracking are frequently obtained during non-weight-bearing knee extension; however, pain typically arises during highly loaded activities, such as squatting, stair climbing, and running. It is unclear whether patellofemoral joint kinematics during lightly loaded tasks replicate patellofemoral joint motion during weight-bearing activities. The purpose of this study was to: evaluate differences between upright, weight-bearing and supine, non-weight-bearing joint kinematics in patients with patellofemoral pain; and evaluate whether the kinematics in subjects with maltracking respond differently to weight-bearing than those in nonmaltrackers. We used real-time magnetic resonance imaging to visualize the patellofemoral joint during dynamic knee extension from 30° to 0° of knee flexion during two conditions: upright, weight-bearing and supine, non-weight-bearing. We compared patellofemoral kinematics measured from the images. The patella translated more laterally during the supine task compared to the weight-bearing task for knee flexion angles between 0° and 5° (p = 0.001). The kinematics of the maltrackers responded differently to joint loading than those of the non-maltrackers. In subjects with excessive lateral patellar translation, the patella translated more laterally during upright, weight-bearing knee extension for knee flexion angles between 25° and 30° (p = 0.001). However, in subjects with normal patellar translation, the patella translated more laterally during supine, non-weight-bearing knee extension near full extension (p = 0.001). These results suggest that patellofemoral kinematics measured during supine, unloaded tasks do not accurately represent the joint motion during weight-bearing activities.

Biomechanics of Patellofemoral Pain

Patellofemoral pain typically arises during activities that place high loads across the knee joint. Abnormal patellofemoral joint motions are thought to cause pain in some subjects by increasing patellofemoral joint cartilage and bone stress. To effectively treat this disorder a better understanding of the joint mechanics is needed. PURPOSE: To identify potential causes of abnormal joint motion in subjects with patellofemoral pain. METHODS: Real-time MRI implemented on a 0.5T Signa SP open-MRI scanner was used to image the patellofemoral joints of 13 pain-free females and 23 females diagnosed with patellofemoral pain. Images were acquired while subjects performed weight-bearing knee flexion/extension from 0 to 60° of knee flexion at a rate of 6 to 10°/s. Measurements of axial-plane patellar translation and patellar tilt were obtained from the images. The sulcus angle at 0° of knee flexion was also measured. RESULTS: On average, subjects with patellofemoral pain exhibited greater lateral translation and tilt of the patella compared to the pain-free subjects; however, there was substantial variation in kinematics among patients with patellofemoral pain. In 30% of the pain subjects, the translation of the patella was no different from the pain-free subjects, while in 50% of the pain subjects the patellar tilt was no different from the pain-free subjects. The sulcus angle at 0° of knee flexion in the subjects with either abnormal translation or rotation of the patella (158±12°) was larger than that of the pain-free subjects (147±10°) and that of the pain subjects with normal kinematics (148±8°, p = 0.046). CONCLUSIONS: It is likely that there are different subgroups of patients with patellofemoral pain and abnormal weight-bearing kinematics may be a mechanism of pain in only some patients. The causes of abnormal joint motion must be identified before effective treatments can be developed. Our results suggest that a greater sulcus angle at 0° (indicative of a more shallow and less constraining trochlear groove) may be related to increased lateral translation and lateral tilt of the patella during weight-bearing knee extension. Future work will use finite element models to evaluate the effects of deep and shallow sulcus angles on cartilage and bone stress at the patellofemoral joint.

Using real‐time MRI to quantify altered joint kinematics in subjects with patellofemoral pain and to evaluate the effects of a patellar brace or sleeve on joint motion

Abnormal patellofemoral joint motion is a possible cause of patellofemoral pain, and patellar braces are thought to alleviate pain by restoring normal joint kinematics. We evaluated whether females with patellofemoral pain exhibit abnormal patellofemoral joint kinematics during dynamic, weight-bearing knee extension and assessed the effects of knee braces on patellofemoral motion. Real-time magnetic resonance (MR) images of the patellofemoral joints of 36 female volunteers (13 pain-free controls, 23 patellofemoral pain) were acquired during weight-bearing knee extension. Pain subjects were also imaged while wearing a patellar-stabilizing brace and a patellar sleeve. We measured axial-plane kinematics from the images. Females with patellofemoral pain exhibited increased lateral translation of the patella for knee flexion angles between 0 degrees and 50 degrees (p = 0.03), and increased lateral tilt for knee flexion angles between 0 degrees and 20 degrees (p = 0.04). The brace and sleeve reduced the lateral translation of the patella; however, the brace reduced lateral displacement more than the sleeve (p = 0.006). The brace reduced patellar tilt near full extension (p = 0.001), while the sleeve had no effect on patellar tilt. Our results indicate that some subjects with patellofemoral pain exhibit abnormal weight-bearing joint kinematics and that braces may be effective in reducing patellar maltracking in these subjects.

Vastus Medialis Activation during Knee Extension Exercises: Evidence for Exercise Prescription

Knee extension exercise is an important part of knee rehabilitation. Clinicians prescribe non-weight bearing exercise initially and progress patients to weight bearing exercise once they can perform a straight leg raise (SLR). Compare VM activation during a SLR and weight bearing exercises. One-way repeated measures design. University Laboratory. Fifteen healthy subjects. One SLR exercise and 6 weight-bearing knee extension exercises. Electromyographic amplitudes for the VM expressed as a percent maximum voluntary isometric contraction. The SLR had greater activation than the single leg stance and bilateral squat exercises. The step-up and unilateral leg press exercises had the greatest activation. SLR performance can be an important indicator for exercise progression. These results provide foundational knowledge to assist clinicians with exercise prescription.

Knee Joint Movements in Subjects Without Knee Pathology and Subjects With Injured Anterior Cruciate Ligaments

Although weight-bearing (WB) exercise and increased hamstring muscle activity may contribute to knee joint stability in knees with an injured anterior cruciate ligament (ACL), the relationship among ACL integrity, muscle activity, and joint surface motion is not fully understood. The purpose of this study was to investigate whether knee joint rolling and gliding movements and electromyographic (EMG) activity differed between subjects with injured ACLs and subjects without knee pathology. Fifteen subjects with injured ACLs (9 men and 6 women; mean age=26 years, SD=7, range=18-36) and 15 age- and sex-matched subjects without knee pathology (9 men and 6 women; mean age=25 years, SD=6, range=18-36) participated in the study. Sagittal-plane knee joint rolling and gliding movements and lower-extremity EMG activity were measured during non-weight-bearing (NWB) and WB movements. Mixed-model analyses of variance were conducted to analyze rolling and gliding and EMG data. During NWB knee extension, greater joint surface gliding occurred in knees with injured ACLs at full knee extension. During WB knee extension, greater gliding occurred in knees with injured ACLs throughout the range of motion tested. No differences in EMG activity occurred between groups. The results suggest that, in the absence of increased hamstring muscle activity, anterior tibial displacement is not reduced in knees with injured ACLs during WB movement.

Medial and Lateral Quadriceps Muscle Activity during Weight-Bearing Knee Extension Exercise

The purpose of this study was to determine the effect of weight-bearing terminal knee extension (WBKE) on normalized mean electromyographic (EMG) activity of the vastus medialis oblique (VMO) and vastus lateralis (VL) and the VMO/VL ratio. Sixteen subjects with no history of knee dysfunction participated. Surface EMG data were recorded from the VMO and VL of subjects' test legs as they performed the WBKE exercise under four conditions, three involving elastic resistance and one involving no elastic resistance. EMG data were normalized relative to a maximal isometric quadriceps contraction, and overall mean VMO and VL activity and the VMO/VL ratio were determined for all conditions. The three conditions utilizing elastic resistance showed higher mean VMO and VL activity than the no-resistance condition. The VMO/ VL ratio was not significantly altered during any exercise condition as compared to maximal, quadriceps setting exercise. WBKE against elastic resistance was superior to the same exercise without resistance for generating mean VMO and VL activity. Performance of the WBKE, regardless of the position of lower extremity rotation, does not selectively activate the VMO apart from, or to a greater degree than, the VL.