KS104 Thigh Adduction/Abduction Trainer — Bilateral Hydraulic Hip Rehabilitation

The ZEPU-KS104 Thigh Adduction/Abduction Trainer is a clinical-grade bilateral hip abduction and adduction rehabilitation machine. The device is used for adduction and abduction of lower limbs, and strengthens the muscle chain of the active and antagonistic muscles. 

The KS104 trains the gluteus medius, tensor fasciae latae (TFL), and gluteus minimus (hip abductors — moving the thigh outward away from the body's midline) and the adductor magnus, adductor longus, adductor brevis, gracilis, and pectineus (hip adductors — moving the thigh inward toward and across the midline) through bidirectional hydraulic resistance — simultaneously strengthening both the primary movers and their antagonists in a single bilateral exercise movement. This paired agonist-antagonist training of the hip's mediolateral muscle groups is clinically fundamental for: pelvic stability during walking and single-leg stance; fall prevention through lateral balance control; hip arthroplasty rehabilitation; post-stroke lower limb recovery; and the management of hip, groin, and knee pain conditions driven by hip abductor-adductor imbalance.

Key Features —

Two-Way Hydraulic Resistance — Low Inertia, Lowest-Limit Start The two-way hydraulic resistance can start from the lowest limit set, with small inertia, so as to avoid damage to patients during use. 

For the specific patient populations most commonly using the KS104 — post-hip arthroplasty patients, elderly patients at risk of falls, post-stroke patients with hip abductor weakness, and patients with hip fracture rehabilitation — the low-inertia, lowest-limit resistance start is a non-negotiable safety requirement. Hip abductor exercises place lateral stress on the hip joint and tensor fasciae latae — in post-surgical and post-fracture patients, any sudden resistance spike or inertial jerk at exercise initiation could compromise surgical repair, provoke pain, or cause patient guarding that inhibits effective training. The hydraulic mechanism's smooth-start, low-inertia resistance profile enables safe exercise initiation for even the most medically complex patients.

Bilateral Simultaneous Training — Abduction and Adduction in Every Repetition The KS104 trains both hip abduction and hip adduction within every complete exercise repetition — the thighs move outward against hydraulic resistance (training abductors concentrically) and then return inward against hydraulic resistance (training adductors concentrically). This bidirectional resistance ensures that neither the abductors nor the adductors are exercised only as passive decelerators — both groups receive active concentric training stimulus throughout the session. The bilateral design also ensures that left and right hip muscle groups are trained simultaneously, maintaining the symmetrical hip strength essential for balanced gait patterns.

Ergonomic Joint Contact — Hip Morphology-Matched Design Special design is adopted for the stressed parts of joints, which conforms to the principle of human morphology. The KS104's thigh pad contact surfaces and hip pivot axis are designed to align with the natural biomechanical axis of the hip's frontal-plane abduction/adduction movement, minimising shear stress at the hip joint and the medial and lateral collateral structures of the knee during the exercise arc. This alignment is particularly critical for post-hip arthroplasty patients where correct force vectors during early rehabilitation directly influence implant stability and the avoidance of dislocation. 

Target Muscles — The KS104 Hip Mediolateral Muscle Chain

Hip Abductors (Outward Phase)

Gluteus Medius — Primary Abductor The largest and most clinically important hip abductor — controlling pelvic stability in single-leg stance and the primary target of the KS104's abduction phase. Gluteus medius weakness produces Trendelenburg gait, increases lateral knee loading (IT band and patellofemoral pain), and is the most common functional deficit following hip arthroplasty, hip fracture, and stroke.

Tensor Fasciae Latae (TFL) The TFL works with the gluteus medius in hip abduction and anterior rotation, contributing to lateral hip stability and through the iliotibial band to lateral knee stability. TFL dysfunction is central to IT band syndrome and patellofemoral pain — two of the most prevalent conditions in runners and active adults — making targeted TFL training a priority in lower limb sports rehabilitation.

Gluteus Minimus The gluteus minimus lies deep to the gluteus medius and acts as a synergist in hip abduction and internal rotation. It contributes to joint compression stability at the hip and works with the gluteus medius to maintain pelvic level during gait.

Hip Adductors (Inward Phase)

Adductor Magnus — Primary and Most Powerful Adductor The largest adductor — with both adductor and hamstring portions — providing the primary medial hip force during the adduction phase. Adductor magnus strength is important for medial knee stability, groin pull prevention in athletes, and the pushoff phase of gait where medial hip force contributes to propulsion.

Adductor Longus and Adductor Brevis These two muscles provide the primary adduction force at mid-flexion angles and are the muscles most commonly strained in groin pull injuries in football, hockey, and basketball athletes. Progressive KS104 adductor loading is the evidence-based foundation of groin strain rehabilitation and return-to-sport adductor programmes.

Gracilis A long, strap-like adductor running from the pubis to the medial tibia — contributing to hip adduction and medial knee stabilisation. Gracilis function is important in single-leg landing mechanics and medial knee stability, and gracilis rehabilitation is a component of post-ACL and medial knee surgery programmes.

Pectineus A short, flat adductor of the superior medial thigh — contributing to both adduction and hip flexion, and involved in the stability of the medial hip in early stance phase.