Clinical Pilates in Practice: Knee Joint Biomechanics in Transtibial Amputees

This study looked at knee joint biomechanics in a young, healthy population with no activity restrictions, with a focus on energy storage and return (ESAR) prostheses. The authors recognise that the study had a small sample size, and discuss potential sources of error for their data collection, but are confident about the clinical application of their findings.

Orekhov G, Robinson AM, Hazelwood SJ, Klisch SM (2019) Knee joint biomechanics in transtibial amputees in gait, cycling, and elliptical training. PLoS ONE 14(12): e0226060.

Key Points: Knee Biomechanics For Transtibial Amputees

• There is a high prevalence of joint pain and osteoarthritis (OA) in unilateral transtibial and transfemoral amputee populations.

• Transtibial amputees are more likely to develop OA in the intact knee.

  Abnormal gait biomechanics include asymmetric ground reaction forces, muscle activation patterns, and knee joint kinetics between limbs.

• Kinematics and kinetics varied with the type of exercise (gait, cycling, elliptical), leg type (residual or intact leg), and participant type (amputee vs control).

• Midstance flexion angle timing and knee flexion angle differed between amputees and controls during gait.

• No differences were seen between amputee vs. control for intact/dominant knee compressive force, extension torque, or abduction torque for any of the exercises.

• Large asymmetries were observed for maximum extension torque for amputees during gait,

  → Muscle coordination and braking/propulsion effort may be altered for the residual leg.

  → Significantly reduced residual knee extension torque may show that ESAR prostheses do not emulate natural biomechanics after amputation, which may cause the intact leg to compensate.

• Transtibial amputees had significant asymmetries between intact and residual knee flexion angle in gait and elliptical, but not cycling.

• Amputees displayed significantly reduced extension torque in the residual vs. intact knee in gait, but not for cycling.

• Cycling had generally lower magnitudes of resultant knee compressive force, extension torque, and abduction torque compared to elliptical training and gait.

  → Knee kinetics were generally lowest in cycling and highest in gait.

• Exercises that constrain kinematics, such as cycling, are more likely to maintain typical cartilage loading patterns.

• Exercises that reduce overall knee joint forces and torques may be preferred for reducing OA risk in this population.

• The present study did not relate exercise type to injury or OA risk

Clinical Pilates in practice

• There are many Pilates exercises that can offload the knee while working to build strength around that joint. However, gait/walking is still an everyday task, therefore working to increase balance and efficiency for increased joint loading is important.

• Choose exercises that minimise compressive stress at the knee, to alleviate abnormal loading of cartilage.

• Improving hip and ankle mobility and stability will decrease joint forces and torque acting through the knee in various positions.

  → Eve's Lunge on the Reformer.

  → Star Overs at the Tower.

  → Flutters at the Tower.

  → Standing Ankle Press at the Wunda Chair.

  → Foot Corrector Series.

• Closed kinetic chain exercises in side lying will minimise gravitational forces through the knee joint.

  → Sleeper/Side Lying Leg Press Series on the Reformer.

  → Side Lying Adductor Series on the Wunda Chair.

  → Hip Openers at the Tower.

• Hands-on incorporation of PNF techniques such as alternating isometrics and/or rhythmic stabilisation through all joints of the lower limb in unloaded and/or open kinetic chain positions can further target stabilisers around those joints.

• Pseudo-closed kinetic chain exercises can be used to challenge stability around the knee as it moves through in space.

  → Feet in Straps on the Reformer or Leg Springs on the Tower.