Knee disorders
Maneesh Bhatia, Tim Jennings in An Orthopaedics Guide for Today's GP, 2017
Acute patella dislocation can be due to contact or non-contact injury. It is almost always a lateral dislocation with the knee in either extension or flexion with valgus stress to the knee or external rotation of the foot. There are often many similarities between the mechanism of injury leading to patella dislocation and ACL rupture. Acute patella dislocation would quite often spontaneously reduce as the patient extends his/her knee after the injury. At other times, acute dislocation may have been reduced by paramedics or in the accident and emergency (A&E) department. Unless the patella is seen in the dislocated position at the time of initial injury, history alone cannot always distinguish a patellar dislocation which has reduced spontaneously from an ACL rupture. It is important as part of history to enquire about previous patellofemoral joint symptoms, instability or dislocations. Clinically, patients would have bruising and pain over the medial aspect of the patella and knee joint. The ‘apprehension test’ as described earlier is likely to be positive (Figure 7.3b).2
Osteoarthritis
Rajan Madhok, Hilary Capell in The Year in Rheumatic Disorders Volume 4, 2004
INTERPRETATION. Subjects aged >45years (men) and >50years (women) were recruited from Veteran Affairs medical centres and from the community. Subjects were asked about knee pain and patients with forms of arthritis other than OA were excluded. Knee pain was defined by asking a simple question about the presence of knee pain in the prior 4 weeks. A subset of patients had the presence of clinical OA confirmed as well as the absence of clinically obvious periarticular sources of pain. All subjects had standardized radiographs of the tibiofemoral and patellofemoral joints as well as an MRI of one, usually the most symptomatic, knee. Clinical examination used a grid to subdivide the knees into specific anatomical areas. Tenderness and pain in these areas were documented by standardized examination. The subjects were divided into three groups. The results are tabulated (Table 11.1). Radiographic OA was associated with fluid in the prepatellar and superficial infrapatellar bursae but interestingly this was not associated with pain. Deep infrapatellar fluid was present in all three groups and was only thought to be symptomatic in three patients, all with knee pain. Other periarticular lesions were common generally in those with pain and on further analysis particularly those with radiographic OA.
Lower extremity injuries
Youlian Hong, Roger Bartlett in Routledge Handbook of Biomechanics and Human Movement Science, 2008
When the knee is fully extended the patella rides high on the femur. As the knee flexes, the patella slides in the intercondylar groove in a movement termed patellar tracking. Effective patellar tracking depends on structural congruence between the patella and femur, the net effect of muscle forces (i.e., vastus medialis, vastus lateralis, vastus intermedius, and rectus femoris) and other structural considerations (e.g., Q-angle). As the patella tracks, contact pressures develop between the patella and femur. These pressures, determined by the contact forces and areas, vary with knee flexion (Figure 27.3). As the knee flexes, PF joint contact area increases and the knee flexes from full-extension, with most of the increase happening in the first 45–60˚ of flexion (Salsich et al., 2003). In addition to increasing in size, the contact area migrates superiorly on the retropatellar surface as the patella slides deeper into the intercondylar groove (Figure 27.3).
On the impact force analysis of two-leg landing with a flexed knee
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2021
Marzieh Mojaddarasil, Mohammad Jafar Sadigh
In order to model the contact of the legs with the ground in drop landing, we used a simple 2D four-link musculoskeletal model, as shown in Figure 1. It was assumed that the two legs move together in complete synchrony with the same kinematics, i.e. the leg motions have left-right symmetry, and therefore, we modeled only half of the body. The four links represent the head-arm-trunk (HAT), the thigh, the shank and the foot. The model has three joints: the hip, knee and ankle. The hip and ankle were modeled as frictionless revolute joints, and the knee joint was modeled as a planar joint consisting of the tibiofemoral and patellofemoral joints according to (Nisell et al. 1986; Yamaguchi and Zajac 1989; Kernozek and Regan 2008). The tibiofemoral and patellofemoral kinematics were defined by the knee flexion angle according to (Delp 1991). In all three joints, no passive moment resistance was considered. Moreover, the tibia and femur are connected to each other via knee ligaments, and the patella segment is connected to the tibia via the patellar ligament (PL). All these ligaments were considered as fixed length strings (Delp 1991).1
The effect of patellar taping on lower extremity running kinematics in individuals with patellofemoral pain syndrome
Published in Physiotherapy Theory and Practice, 2019
Ariel Pelletier, Paolo Sanzo, Derek Kivi, Carlos Zerpa
Taping was also found to have a statistically significant effect on peak knee and hip flexion angles during the swing phase. In fact, the application of LT and the no tape conditions allowed for greater knee flexion during swing than the application of KT. The greater knee flexion associated with the application of LT is once again in agreement with Powers et al. (1997) and Salsich, Brechter, Farwell, and Powers (2002). However, an increase in knee flexion results in greater patellofemoral joint compression (Aminaka and Gribble, 2005; Campolo et al., 2013; Lan, Lin, Jiang, and Chiang, 2010; Mostamand, Bader, and Hudson, 2010; Osorio et al., 2013). As a result, the increased knee flexion during swing associated with the application of LT may lead to individuals with PFPS experiencing more pain, if applied clinically. Nevertheless, all of the peak knee flexion angles observed during the swing phase of this study was within the expected typical range reported in the literature (Novacheck, 1998).
Patellar fracture among elite-level European soccer players: 4-year case-control cohort analysis of return to play, re-injury, and player performance
Published in The Physician and Sportsmedicine, 2023
Sumit Patel, Ophelie Lavoie-Gagne, Nabil Mehta, Ghassan Farah, Avinaash Korrapati, Brian Forsythe
Patellar fractures most commonly occur through excessive tension on the extensor mechanism (via forceful contraction of quadriceps) or through direct trauma [7]. Patellar fractures can cause weakness in leg extension, knee stiffness, and, chronically, patellofemoral arthritis. Among patellofemoral injuries, patellar fractures appear to have the highest incidence of surgical intervention [8]. Non-displaced fractures with an intact extensor mechanism may be treated through conservative management – cast immobilization followed by progressive range of motion and strengthening exercises. Fractures with displacement (>3 mm displacement or >2 mm of articular incongruity), open fractures, or fractures associated with a deficient extensor mechanism are indications for surgical intervention, which include internal fixation using tension bands, lag screw fixation, partial patellectomy, or total patellectomy [9].
Related Knowledge Centers
- Femur
- Hinge Joint
- Synovial Joint
- Thigh
- Tibia
- Osteoarthritis
- Joint
- Patella
- Leg
- Fibular Collateral Ligament