The Effect of Commercially Available Footwear Interventions on Biomechanical Outcomes Associated With Knee Osteoarthritis in Meniscectomy Patients

Injuries to the meniscus are common in sport, often as a result of a traumatic event. Mitchell et al. (2016) reported 5.1 meniscal injuries per 100 000 athletic exposures, with a greater proportion reported during competition (11.9 injuries per 100 000 athletic exposures), compared to practice (2.7 injuries per 100 000 athletic exposures). Rotation around a planted/ inverted foot has been cited as a common mechanism for meniscal injuries, followed by landing and jumping movements. The meniscus aids in stabilising the knee, acting as a shock absorber and transmitting load. Damage to the meniscus is suggest to lead to altered knee mechanics leading to the initiation or acceleration of osteoarthritis (OA) development. Prior meniscal tears are commonly reported in OA patients, in addition, reports suggest 4 to 14 times increased risk of developing OA following a meniscal injury.

Altered knee mechanics have been reported following a meniscal injury, which have been associated with increased likelihood of developing OA. These changes include reduced contact area within the joint and increased contact pressure, resulting in reduced ability to transmit load. Indirect measures of knee loading, such as external knee adductor moments (EKAM) and knee adduction angular impulses (KAAI), have been associated with increased risk of developing OA. Knee joint loading is also determined by the coordination of muscle activity. Greater and longer co-contractions of the medial muscles at the knee have demonstrated faster development of OA in individuals diagnosed with medial knee OA.

Meniscectomies are widely used to manage the symptoms associated with meniscus injuries. Whilst, non-operative therapies have demonstrated improvements in knee pain three years post intervention. However, following these interventions, alter mechanics of the knee have been observed. For instance, following a medial meniscectomy, increases in contact area and pressure at the knee have been observed and suggested to increase the likelihood of developing OA. Increases in EKAM in meniscectomy patients have been associated with changes in tibia alignment and GRF lever arm. Non-invasive interventions such as footwear, could alter biomechanics to lower EKAM and reduce the progression of OA. Following a meniscectomy procedure, most patients tend to go back to wearing their old trainers. Due to the changes in the biomechanics of the knee, it can be assumed that they support and cushioning they need would change too.

Typical sports movements such as landing and cutting require dynamic control of the knee which is very under-researched. Muscle strength recovery is also considered to be important for young individuals after an arthroscopic surgery in order to regain capacity to participate in sports or other activities as both pre- and post-operative knee extensor strength have been reported to predict better functional outcome of knee surgery. The co-contraction between the quadriceps and hamstrings are also important in this as muscle weakness creates a less stable base. Muscle strength is also essential to control movements such as stair descent which is essential for everyday living. This is closely linked with balance and the risk of falling. Having extra support or cushioning in footwear can help aid this control needed for static and dynamic exercises especially post-surgical intervention.

Different footwear interventions have been used in OA patients to reduce knee loading and pain. Lateral wedges have demonstrated reduced medial knee loading in both affected and contralateral limbs. In addition, mobility shoes and lateral wedges which provide additional medial support have been shown to reduce pain in OA patients. However, it is unclear whether footwear interventions are able to alleviate the risk factors associated with the progression of OA following a meniscal injury. For effective self-management, post operation the appropriate footwear is recommended, however there is little evidence to inform what the appropriate footwear is for patient after surgery or with knee OA.