Patient Presentation | Crouching

This article is the seventh and last in a series that explores clinical groups of common bracing applications.

Crouching is usually the result of weakness or spastic contractures. Patients with weakness in the muscle groups that control knee position will often crouch when muscle strength is insufficient to maintain an upright posture. For patients with chronic high tone contractures of the hamstrings, the knees are pulled into a flexed position, resulting in a crouched posture.

Assessment

To begin to understand the factors leading to crouching, an assessment of the patient’s muscle tone, level of voluntary control and range of movement of the entire kinetic chain is important. Knowing all the underlying causes, however, may take considerable time to fully ascertain. The general severity of the crouching can be gauged based on several factors:

• Mild crouching can be voluntarily corrected, is inconsistent or irregular and mildly affects posture.

• Moderate crouching is difficult to voluntarily correct, might be inconsistent yet frequent and moderately affects posture.

• Severe crouching cannot be voluntarily corrected, is consistent and significantly affects posture.

Some simple testing will help quickly determine how much postural improvement is possible and whether DAFO/AFO bracing will be effective. Here are two assessment techniques.

Note: If the patient cannot maintain these corrections on his own, you may be creating a false sense of the amount of correction possible. When using an AFO, you won’t be there to hold them.

Method 1

• With the patient standing and holding on to something secure (or being held securely by someone else), attempt to correct the crouched posture by gently pushing on the front side of the patient’s knees.

• Repeat until you have a good sense of how much correction is possible for each limb and how much resistance there is to the correction.

Method 2

• Have the patient stand with his back towards you. Kneel directly behind the patient with your knees placed behind the patient’s feet. Place your shoulders against the patient’s lower back.

• Reach around the patient and place your hands on his knees. Gently pull back on the knees while supporting the patient’s upper torso with your shoulders.

• Repeat until you have a good sense of how much correction is possible for each limb and how much resistance there is to the correction.

Patients with weakness in the quadriceps femoris often crouch due to insufficient strength. A patient may have the required strength to stand upright initially, but will begin to crouch more and more as he becomes fatigued and existing strength diminishes. Hence, a mild or moderate crouching posture may only be temporary, replaced by more severe crouching as the patient fatigues. In most cases, supplementary support (walker, crutches, braces, etc.) is required to maintain and stabilize an upright posture.

The very mildest form of crouching, also discussed in the “Inconsistent Ankle Modulation” article (Summer/July 2007 Dafo Dynamics), may only require a proprioceptive reminder of ankle position. The DAFO 4 with an anterior strap works well for this task.

For mild to moderate crouching, where the patient’s voluntary control is sufficient to maintain a relatively upright posture with little or no supplemental support, the DAFO 3.5 brace with the flexible proximal upright provides spring-like resistance to both plantarflexion and dorsiflexion. The brace provides supplementary support that helps increase stability and endurance. If the patient would overpower a 3.5 but the Turbo would be too much, the FlexiSport^TM is an appropriate choice to consider.

As the severity of muscle weakness increases, the patient’s ability to maintain an upright position decreases. The brace must take on a more substantial role in supporting the patient and thus needs to be stronger and more rigid. For smaller patients, the DAFO FA (fixed ankle) provides sufficient dorsiflexion block. For the larger patient, the DAFO Turbo brace provides sufficient dorsiflexion block to support a larger, heavier patient, while providing substantial control of foot alignment.

Crouching Due to Spastic Contractures

Patients with chronic high tone contractures of the hamstrings (semimembranosus, semitendinosus, biceps femoris) slump into a crouched posture as the upper and lower leg segments are pulled together by the hamstrings. DAFO braces do not span the knee; hence, they cannot control the relationship of the upper leg to the lower leg by controlling the angle of the knee. Blocking ankle dorsiflexion with a DAFO brace shifts the knee back over the foot, but it has little direct effect on knee flexion.

In moving the knee position backward, most of the patient’s weight will shift rearward, throwing the patient off balance. To compensate, the upper torso will bend forward at the hips or the patient will bring his or her torso weight forward by rising up onto the toes/forefoot. If the patient’s center of gravity cannot be adjusted back over the foot, the patient will fall backwards.

Despite these limitations, some postural correction may be available that can be beneficial to the patient’s stance and gait. Again, some simple testing will help quickly determine how much postural improvement is possible. In most cases, the higher control of the DAFO FA (for smaller patients) or DAFO Turbo are required.

If the hamstring contractures causing the crouched posture are accompanied by contractures of the calf muscles (excess plantarflexion), the patient will stand and walk with forefoot contact only. The ligaments and tendons of the foot eventually stretch due to the force the body weight places on the forefoot and midfoot. Over time, this can lead to a condition called “rocker-bottomed foot” where the midfoot begins to flex to compensate for the rigidity of the ankle, forming a rounded plantar surface along the longitudinal axis of the foot. The hinge-like flexibility of the midfoot allows the forefoot and some of the midfoot to be in ground contact while the heel remains off the ground. Although improvement in knee or ankle function may not be feasible, limiting or preventing the breakdown of the foot into this rocker-bottomed condition should be prioritized. The heel and foot position control of the Turbo can help to preserve foot structure.

Method 1 DAFO 4 DAFO 3.5 Clockwise, from top: DAFO FA (Fixed Ankle) and DAFO FlexiSport