Using Wii to Detect Changes in Center of Balance

Following hip or knee joint replacement, a slight leg-length discrepancy can often occur. This slight difference in leg length shifts an individual’s center of balance, challenging both the static and dynamic balance of the joint recipient. The leg-length discrepancy can be a contributing factor in a person’s decrease in functional ability.

Those recovering from joint replacement surgery often demonstrate decreased standing tolerance and balance, decreased flexibility, and pain. Faced with increased pain and decreased flexibility, individuals avoid weight bearing and weight shifting, which can contribute to the development of a compensatory gait pattern. Though the literature points out that the impact of a leg length discrepancy continues to be debated, for the clinician whose goal is to restore functional independence, this possible contributor to dysfunction should be considered.

The Wii Fit Balance Board offers the therapist an easy way to assess center of balance. The Body Test calculates the players center of balance as well as their BMI. This Body Test also measures an individual’s body control, or their ability to keep their weight centered. Games or activities included with Wii Fit help teach a person how to move their body to improve their ability to maintain the optimal center of balance. The games provide feed back for improvement in several ways. For example, in the ski jump activity, a small box in the upper right hand corner of the screen uses a small blue dot floating inside a larger yellow dot to indicate the player’s center of balance. If the individual maintains their body alignment in an optimal position prior to extending their knees for the “jump”, the distance of the jump is longer, resulting in a higher score. The visual feedback from the dot, along with the positive reinforcement from increasing scores, help motivate the participant to keep trying to improve their weight shifting and weight bearing.

If a client has continued difficulty maintaining their center of balance, the therapist may suspect a leg length discrepancy. Although length discrepancies are often not reported and may be rare, following surgery for a single knee replacement, some patients report discrepancies of up to a quarter of an inch. An orthotist can place an insert inside the shoe, correcting this issue. Often, clients sense the correction immediately because eliminating the difference in leg length, helps to align the pelvis. An orthotist can again use a lift to correct this imbalance. Hip replacements may also lead to one leg being shorter and one being longer.

Now the client, wearing his adjusted shoes, may have an easier time maintaining his center of balance. The therapist will need to always take precautions for fall prevention when using the Wii Sports or the Wii Fit for therapy in a population with joint replacements. Some of the balance games may not be appropriate for early stages of rehab for those with joint replacement because of pain or weight bearing restrictions or precautions, but maybe quite helpful in the latter stages of therapy as the client progress toward full recovery.