This study was designed to assess the effect of an 8-week plyometric-based hydro-kinesio therapy (Plyo-HKT) on pain, muscle strength, postural control, and functional performance in a convenience sample of children with hemophilic knee arthropathy (HKA). Forty-eight patients with HKA were randomly allocated to the Plyo-HKT group (n = 24, received the plyometric-based hydro-kinesio therapy program, twice/week, over 8 weeks) or the control group (n = 24, received standard exercise program). Both groups were assessed for pain, muscle strength, postural control, and functional performance pre and post-treatment.

Forty-eight boys with moderate hemophilia-A were recruited from the hematology clinics of three large referral hospitals in Riyadh, Saudi Arabia. The study included patients who were 8-16 years old, had factor VIII replacement prophylaxis, were clinically-stable cases, had unilateral knee hemarthrosis, had grade II or III knee arthropathy, had muscle strength of grade three, and if they were able to walk independently. Patients who had enduring disabling pain, fixed deformities, a history of musculoskeletal surgery, visual and/or vestibular deficits, or bleeding episodes within two weeks before enrollment were excluded.

Outcome measures

Pain: Pain during rest and/or movement was assessed using the Numerical Pain Rating Scale.

Muscle strength: The peak concentric torque of the quadriceps and hamstring muscles was measured through an Isokinetic Dynamometer.

Postural control: The directional dynamic limit of stability (forward, backward, affected, and non-affected) and overall limit of stability were assessed using the Biodex balance system.

Functional performance: The extent of functional capacity was assessed through the functional independence score in hemophilia and the six-minute walk test.

Interventions

The Plyo-HKT group received the Plyo-HKT program, 45 minutes per session, two times a week for 8 consecutive weeks, in conformity with the National Strength and Conditioning Association guidelines and American Academy of Pediatrics safety standards. The Plyo-HKT program consisted of ten unilateral and bilateral lower limb plyometrics in the form of hopping/bounding/jumping activities conducted in a water medium. The Plyo-HKT included a warm-up for 10 minutes and a cool-down for 5 minutes. The control group received the standard exercise program, 45 minutes per session, two times a week for 8 consecutive weeks. The program consisted of flexibility exercise, strength training, weight-bearing, proprioceptive training, and free treadmill walking or cycle ergometry.

Inclusion Criteria:

• Eight and 16 years.
• Had factor VIII replacement prophylaxis.
• Clinically-stable.
• Unilateral knee involvement.
• Knee arthropathy of grade II or III per the Arnold-Hilgartner radiographic classification.
• Muscle strength of grade 3 in lower limb muscles.
• Use of no pain medication for one month prior to enrollment.
• Walking independently.

Exclusion Criteria:

• Enduring disabling pain
• Fixed deformities.
• History of musculoskeletal surgery.
• Visual or vestibular deficits.
• Engagement in regular exercises.
• Bleeding episodes within two weeks prior to enrolment.

This was a single-blind protocol. The researcher who collected the data was blinded to the treatment allocation.