1B Lab Activities: Integrated Function of the LE - PDF

**Kinesiology Lab: December 3, 2024** **Learning Outcomes:** At the end of this lab, students will be able to: - Describe the classification, kinematics, and unique characteristics of the hip, knee, ankle and foot. - Predict effects of different joint restrictions on the LE function...

**Kinesiology Lab: December 3, 2024** **Learning Outcomes:** At the end of this lab, students will be able to: - Describe the classification, kinematics, and unique characteristics of the hip, knee, ankle and foot. - Predict effects of different joint restrictions on the LE function for balance and gait. - Begin to extend knowledge of kinesiology to exercise prescription. **1. Summary of LE kinematics** Please review the following information. You should know the classification and ROMs from your anatomy class. For this class, please have an understanding of the function ROM needed, the loose- and close-packed positions, capsular patterns, and end-feels. A. **Coxofemoral (hip) joint:** Type: diarthrosis, spheroidal, ball-and-socket DOF = 3 (FLEX-EXT, ABD-ADD, LR-MR) Physiological (active) ROM: - Flexion: 110-120° - Extension: 10-15° - Abduction: 30-50° - Adduction: 30° - Lateral Rotation: 40-60° - Medial Rotation: 30-40° Functional ROM: - End-Feel - Flexion: Firm/soft tissue approximation (STA) - Extension: Firm - Abduction: Firm/Hard - Adduction: Firm/STA - Lateral Rotation: Firm - Medial Rotation: Firm - Capsular Pattern - Limitation in flexion \> abduction \> medial rotation - Close-packed Position - Full extension, full medial rotation, and slight abduction - Loose-packed Position - 30° of flexion, 30° of abduction, slight lateral rotation B. **Tibiofemoral (knee) joint:** Type: diarthrosis, hinge DOF = 1 (FLEX-EXT) -- Note: owing to the morphology of the knee, there is a rotation movement coupled with flexion and extension Physiological (active) ROM: - Flexion: 135° - Extension: 15° (hyperextension) - Internal Rotation: 20-30° - External Rotation: 30-40° - Abduction/adduction: tightly controlled (normally) Functional ROM:  - End-Feel - Flexion: STA - Extension, IR and ER: Firm - Capsular Pattern - Flexion \> extension - Close-packed Position - Full extension, lateral rotation the tibia - Loose-packed Position - Mid flexion \~25° C. **Patellofemoral joint:** Type: diarthrosis, planar DOF = 0 -- functionally allows SUP-INF glide and MED-LAT glide - End-Feel - Firm in all directions - Capsular Pattern - Flexion \> extension - Close-packed Position - Full flexion - Loose-packed Position - Full extension (relaxed) D. **Talocrural (ankle) joint:** Type: diarthrosis, hinge DOF = 1 (DF-PF) -- Note: owing to the morphology of the knee, there is coupling of rotation and tilting of the talus Physiological (active) ROM: - DF: 10º to 15º/20º - PF: 50º to 70º Functional ROM: - Walking: 10º DF and 15-20º PF - Stairs: 20º DF and 20-30º PF - End-Feel - DF: Firm/hard; tension in the posterior joint capsule, deltoid calcaneofibular and posterior talofibular ligaments, plantarflexors, and contact between the talus and the tibia. - PF: Firm/hard; tension in the anterior joint capsule, anterior deltoid and talofibular ligaments and dorsiflexion, and contact between the talus and tibia. - Capsular Pattern - PF \> DF - Close-packed Position - Maximum DF - Loose-packed Position - 0-10° of PF E. **Subtalar joint:** Type: diarthrosis, plane DOF = 0, functional allows glides in ABD-ADD and EV-INV Physiological (active) ROM: NONE Accessory motions: - INV: 20-30º - EV: 5-10º - **The subtalar joint contributes 10% of the DF ROM** 1. **unctional ROM for Gait:** - **Inversion**: Approximately 4--6 degrees. - **Eversion**: Approximately 4--6 degrees. - This combined motion allows for the necessary pronation and supination during walking. Functional ROM: - Walking: 4-6º of INV and EV for a total range of 9-12º - End-Feel - INV: Firm; tension in the lateral collateral ligament, evertors talocalcaneal ligaments and lateral joint capsule - EV: Firm/hard; contact between the talus and calcaneus, tension in the medial joint capsule, medial collateral and medial talocalcaneal ligaments, tibialis posterior, flexor hallucis longus and flexor digitorum longus - Capsular Pattern - INV \> EV - Close-packed Position - Supination -- a combination of talocrural DF, subtalar INV/ADD, and foot adduction - Loose-packed Position - Pronation -- a combination of talocrural DF, subtalar EV/ABD, and foot abduction **2. Pelvifemoral rhythm of the gait cycle** As we have previously discussed, the gait cycle consists of two phases (stance and swing), each having sub-phases as shown below. Knowledge of these sub-phases **is necessary**. From a kinetic perspective, the stance phase includes a force absorption phase, a transition phase, and a propulsion phase. These subphases of the stance are associated with specific 'linked' kinematics of the LE joints, as follows: - Heel strike = in slight supination with LE in ER - Weight-acceptance = into pronation and LE IR - Midstance = neutral position with LE moving from IR to ER - Push-off = increasing supination to toe-off, with LE in ER (locking at hip and knee) These linked LE joint motions yield a predictable pattern of pelvic rotation on the weightbearing leg and, ultimately, path of the CoP under the foot.  This motion of the pelvis on the femoral head (hip joint) is referred to as the pelvifemoral rhythm. The figure above shows the rotation of the pelvis (from a superior view) in the transverse plane. The motion of the pelvis will induce coupled motions at the hip joint, as follows: - A. Forward rotation of the pelvis around the left (weightbearing) hip results in medial rotation at the left hip. - B. Neutral position of the pelvis should be balanced by joint reaction forces and hip abductor moment. Therefore, this should provide a transition from lateral to medial rotation at the left hip. - C. Backward rotation of the pelvis around the left (weightbearing) hip results in lateral rotation at the left hip. Table 10.1 below summarizes the compensatory motions at the hip and lumbar spine with different motions of the pelvis. Please review this information and answer the following questions. 1a. Application questions: - What would be the impact of the following restrictions in motion on the gait cycle: - Decreased lateral flexion of the lumbar spine on the weightbearing side: \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ - Decreased medial rotation of the hip on the weightbearing side: \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ - Decreased lateral rotation of the hip on the weightbearing side: \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ **To better understand these relationships, try them out -- make notes to help you remember the information.** **\ ** **3. Self-directed learning -- calculation of forces and moments on the hip joint** Using information on pages 344-350, create study notes, free-body diagrams, or other that will assist you in understanding the forces that are exerted on the hip. You should be able to apply this knowledge to predict effects of different conditions, such as unilateral weakness of hip abductor muscles.  [Write out your answers to the following two questions: ] Using the force diagram above, can you explain the effect of increased body weight on the risk for femoral neck fracture? In the same way, can you explain the effect of osteoporosis on the risk for femoral neck fracture? Can you show what would be the resultant effect of a decrease in the moment-generating capacity of the hip abductor muscles? 2a. In the frontal plane during bilateral stance, the HAT weight is transmitted through the SI joints and pelvis to the right and left femoral heads. This weight is borne on the anterior / medial surface of the head of the femur and, reciprocally, on the superior-anterior region of the acetabulum. These are areas are somewhat protected by having thicker cartilage on the head of the femur and increased stiffness of the acetabular labrum. In bilateral standing, it is assumeed that the LoG passes through the body CoM. Accordingly, the moment arm (MA) of the weight of the HAT will be symmetrical on both sides as the distance between the LoG and the center of the femoral head, as shown below.  [Now let's put this knowledge to practice ] We will use the values provided in the text: BW = 825 N MA~HAT~ = 0.1 m MA~Hip-ABD~ = 0.05 m Also note that 1 lb = 4.45 N The summary of all calculations presented here are available in Table 10-2. Step-by-step explanation: A. The moment of gravity is an opposite direction on the right and left hip (remember right-hand rule of moments). Therefore, the weight of the HAT around the right hip will tend to drop the pelvis down on the left (right adduction moment). By contrast, the weight of the HAT around the left hip will tend to drop the pelvis down on the right side (left adduction moment). B. Compressive joint reaction force on the femoral head will be needed to balance the gravitational moments when there is a transition to unilateral stance (e.g., gait). In unilateral stance, one hip will need to support the weight of the HAT (2/3 of the BW) and the weight of the unsupported leg (1/6 BW) -- a total of 5/6 of the BW. This combined weight vector (HAT-LL) will create an adduction moment around the weightbearing hip joint (i.e., tend to drop the pelvis down on the opposite side -- side of the unsupported LL). The abduction counter moment to counteract this adduction moment will need to be **actively provided** by the hip abductor muscles on the weightbearing side. **Active muscle contraction will provide the necessary additional joint reaction force**. Calculate the moment that must be generated by the hip abductor muscles on the weightbearing side (F~m~) using the values provided. Follow along with the text. Remember that to balance moments, the moment of the HAT-LL must equal the moment of the hip abductor force, where the moment is the force X MA (Nm). Once you have calculated the required moment of force of the hip abductor muscle, calculate the total compression force that needs to be exerted on the weightbearing hip (N). **Write out your calculations here.** 2c. **Application questions** Now that you can perform these calculations, please apply these to explain the following clinical scenarios (please write out your answers): - Why would a person with a painful hip (such as OA) lean the trunk over the painful hip during single leg stance (known as antalgic gait)? - What is the cause of a Trendelenburg gait (also known as Gluteus Medius gait)? How would you explain this clearly to a patient? - Using calculation of the balancing of forces in unilateral stance, why should a cane be used on the opposite side (and not on the same side) as a painful and/or weak hip? (see the figure below from the text as a reference). -  - How would you explain this to a patient? - What would be the effect of a change in the angle of inclination of the femoral neck on the balance of moments and forces in unilateral stance? Use the reference diagram below to explain this as a function of the MA of the hip abductor muscles. Hip abductor moment arm - a mathematical analysis for proximal femoral replacement \| Journal of \... - Knowing the relationship between angle of inclination, when performing a total hip replacement, would placing the angle of the femoral neck into a direction of coxa vara be beneficial? Why? - As a last though exercise, why could weakness of the hip abductors be associated with increased activation (and eventual shortening) of the quadratus lumborum on the opposite side? Draw this out. **3. The tibiofemoral (knee) joint** In relaxed standing with a neutrally aligned LE, the LoG (mechanical axis) of the LE will pass through the center of rotation of the hip, knee, and ankle joints. At the knee, under this condition, the weightbearing forces are distributed equally between the medial and lateral condyles. However, during dynamic activities (such as gait), the mechanical axis shifts medially. This medial shift increases the compressive forces on the medial side of the knee.  The tensile force of the MCL plays an important functional role in controlling the resultant effect of this medial shift in the mechanical axis of the LE during dynamic tasks. Specifically, the tensile force developed in the MCL with the resulting motion of the knee into valgus (which stretches the MCL) generates a laterally directed component of the joint reaction force (as shown in the Figure below). This is important as you remember that the axis of rotation of the tibiofemoral joint is strongly restrained on the medial compartment (which the large arc of motion on the lateral tibial plateau).  - Knowing this, why would training / facilitating the dynamic strength and neuromuscular control of muscles on the lateral aspect of the leg and trunk be an important component of a prevention program for MCL injuries in sports? (Write down your answer). - Referring to the Figure below, where would you predict the tear to occur in the medial meniscus to occur with a lengthened or rupture MCL? - What would be the cause? (Remember that the menisci are wedged shaped an provide tensile restraint to the 'glide/slide' movement of the femoral condyles'.  From text: According to Good et al., the MCL provides about 57-60% of the restraint against valgus stress with the knee in extension. This increases to 78-80% when the knee is in 25° of flexion. Clinically, the MCL does not usually require surgical repair (and this even in multi-ligament injuries of the knee). The MCL has rich blood supply providing it with the capacity to heal when ruptured or damaged. Nevertheless, the remodeling process can take up to a year. **Knowing this information, in the early phase of MCL healing, would you select OKC or CKC? Explain why.** 3a. The MCL works with the ACL to resist anterior translation of the tibia on the femur (or posterior translation of the femoral condyles on the stable tibial plateaus). The cruciates (ACL and PCL) create a 4-bar linkage that tightly couples the center of rotation of knee motion on the medial compartment. **Application activity**: Match the ACL and PCL tension patterns to the following two motions:  **Application activity**: Now, can you explain the tension patterns in the ACL and PCL in OCK motions of the knee? (Write down you answers, mapping to the arthrokinematics of the tibial plateaus (on the fixed femur).  Active muscle tensions can increase or decrease the strain on the cruciates (see Fig. 11-18 as an example).  In weightbearing (CKC) (Reference p. 371-372) - Soleus concentric contraction = posterior tibial translation -- assist ACL - Hamstrings concentric contraction = posterior tibial translation -- assist ACL, particularly in greater range of knee flexion - Gastrocnemius concentric contraction = anterior tibial translation (or posterior femoral translation) -- assist PCL - Isolated quadriceps concentric contraction in full knee extension = anterior tibial translation -- increase strain on ACL This emphasizes the importance of neuromuscular control in reducing the risk for ACL injuries in sports. For example, co-activation of the hamstrings with the quadriceps allows the hamstrings to counter the anterior translation imposed by the quadriceps contraction to reduce the strain on the ACL, particularly at knee flexion angles ≥60°. (NOTE: co-activation of opposing muscle groups does increase the total compressive joint reaction forces). **Application question**: Find an exercise program for early post-ACL repair. Justify the exercises used based on your knowledge of the effects of joint position, arthrokinematics, and neuromuscular control on the strain of the ACL. Note that the graft and attachment site are their weakest at 2-4 weeks post-repair. **Please make notes of your program and justification here.** **Please review the Summary of Knee Joint Stabilizers (Table 11-1, p. 387) and Components of Rotary Stability (Table 11-2, p. 388)** **4. Patellofemoral joint** The patella increases the MA of the quadriceps muscle in knee extension. In knee flexion, a large moment of the quadriceps is created by the rounded contour of the femoral condyles. Therefore, there is an effective MA of the quadriceps throughout the range of knee motion. The peak moment generating capacity of the quadriceps is in the range of 45-60° of knee flexion -- both the MA and length-tension relationship of the quadriceps is maximized (this will be the range in which the quadriceps will generate the greatest strain in the ACL). The main functional effect of the patella is at 15° of flexion (in the end-range of extension) where the ability of the quadriceps to generate a moment of force on the tibia is at a minimum.  **Application question:** Considering this information, which exercise would you select to begin increasing the strength of the quadriceps at 4 weeks post ACL repair? Explain why? **OKC of CKC at 45-60°**  **[Write you answer here:]** Contact between the femur and the patella varies with the angle of knee position.  Motions of the patella OKC (femur is fixed and tibia as free to move). The patella is influenced by the quadriceps tendon superiorly and the patella ligament inferiorly. - Knee flexion (from extension) is associated with medial rotation of the tibia, the patella glides inferiorly in the intercondylar groove. - In full extension, the patella is situated laterally in the femoral sulcus. - As knee flexion is initiated, the (large) lateral femoral condyle pushes the patella medially (inducing a medial rotation) of the tibia. - The patella then rotates lateral (about 5°) from 20-90° of knee flexion. - At ≥30°, the patella remains fairly stable as it is tightly constrained between the femoral condyles. At 20° of knee flexion, the compressive joint reaction force at the PFJ is about 25-50% BW. With greater knee flexion (and with running and higher levels of quadriceps activation), the JRF at the PFJ can increase to 10x BW. Deep knee flexion exercises require large magnitudes of quadriceps activity (particularly when weights are added) = substantially high JRFs at the PFJ. Remember that the contact area on the patella is small. This results in large magnitudes of stress on the patella, particularly the medial facet which has a significantly smaller joint contact area compared to the lateral facet. - Protective mechanisms - Full extension -- naturally minimal compressive JRFs on medial facet. - From 30-70° of flexion, contact on the medial facet is near the central ridge of the patella which has thick articular cartilage (among thickest hyaline cartilage in the body). - This is also where the MA of the quadriceps is the largest (45-60° of knee flexion) -- therefore less quadriceps force to produce same moment on the tibia. - Extension to 90° of flexion -- increase in the area of contact which disperses the magnitude of stress - At \>90°, the JRFs on the PFJ increases as the contact area on the patella decreases. However, the quadriceps tendon is now in contact with the femoral condyles which dissipates a portion of the compressive JRF. **Application questions**: \(A) The vertical position of the patella will influence the compressive JRFs on the PFJ. Normally, the 1:1 ratio between the patellar tendon and the length of the patella (known as the Insall-Salvati Index) ensures a functional vertical position of the patella on the femur. - Define patella alta and describe the effects on the kinematics of the PFJ from extension to flexion and the resultant compressive JRFs? - Define patella baja and describe the effects on the kinematics of the PFJ from extension to flexion and the resultant compressive JRFs? \(B) The relative alignment between the femur and the tibia will influence the line of pull of the patella. Normally, the Q-angle is 10-15° (see the figure below). \(C) The orientation of the 4 components of the quadriceps are shown in the figure below. Note that the VL and VM both exert a posteriorly directed vector of force. This component of the VL and VM muscle forces increase the net compressive JRF on the PFJ, even in knee extension.  **5. Talocrural (ankle) joint** The axis of the talus in the ankle mortise is oriented at 14° of inclination in the transverse plane and is rotated about 23° in the frontal plane.  This position of the talus in the mortise is dictated by the articular surfaces of the talus -- the trochlea, the smaller medial facet, and the larger lateral facet. The resultant axis is therefore oriented more distal and posterior on the lateral than medial side of the talocrural joint. The oblique axis of orientation causes a natural coupling of motions along the 3 planes of anatomical motion (i.e., creates triplanar motion). - OKC = DF is associated with abduction (talus brought slightly lateral to the leg -- lateral tilt of talus) and eversion (foot rotates longitudinally away from midline -- medial tilt of talus). Conversely, PF is associated with adduction and inversion. - CKC = DF (forward motion of the tibia over the talus) is associated with medial rotation of the tibia and fibula. PF (posterior motion of the tibia over the talus -- is limited) is association with lateral rotation of the tibia and fibula. - Talar motions are small (7-10° talar rotation and \