Ankylosing spondylitis (AS) -- a chronic inflammatory arthritis primarily affecting the spine -- produces a characteristic forward stooped posture (kyphosis) in advanced disease as the spinal segments fuse in flexion. This altered posture changes the mechanics of cane use in ways that most cane guidance does not address. A cane selected and fitted for normal posture may be incorrect for the AS-related forward-lean posture that many patients develop.
How AS Changes Cane Mechanics
In normal upright posture, the wrist-crease formula provides the correct cane height for 15-20 degrees of elbow flexion. In forward-stooped AS posture, the effective distance from the hand to the ground changes: the trunk leans forward, bringing the hand lower relative to the floor even with the same arm position. A cane sized for upright posture may be too short for the actual walking posture, creating excessive elbow flexion and reduced leverage.
Cane height for AS should be assessed in the patient's actual walking posture, not in a corrected-for-measurement upright posture. The physiotherapist or orthotist should observe the patient walking at their natural pace and height before specifying cane length.
Pain Locations and Cane Function
AS pain is primarily in the spine and sacroiliac joints -- not typically in the hip or knee as in OA. A cane does not directly offload the spine or sacroiliac joints in the same way it offloads a hip or knee. Its function in AS is primarily:
- Balance support: forward-leaning posture shifts the centre of mass forward, reducing the stability margin and increasing fall risk. A cane provides a forward stability point that compensates for this
- Fatigue management: AS produces significant systemic fatigue, particularly during flares. A cane that reduces walking effort allows more activity before fatigue onset
- Hip and knee involvement: approximately 30-40% of AS patients develop peripheral joint involvement (hip, knee). In these cases, the cane provides the same contralateral load reduction as in OA
The Posture Question: Does Cane Use Worsen Stooping?
A concern sometimes raised: does forward-leaning on a cane worsen the kyphotic posture of AS? The evidence does not support this concern for correctly fitted cane use. A too-short cane forces forward lean -- which is why height assessment in AS must be done in actual walking posture. A correctly fitted cane provides a forward stability point without forcing additional trunk flexion beyond the patient's natural posture.
Hip Involvement in AS and Cane Placement
When AS involves the hip (coxitis), total hip replacement is sometimes required in severe cases. Post-surgical cane use follows the standard hip replacement protocol: cane on the contralateral side, 4-6 weeks progressive weight-bearing. See the linked article on hip replacement cane use for the post-surgical protocol.
Exercise and AS: The Physiotherapy Priority
AS is among the conditions where exercise is most critical to disease management. Spinal mobility exercises, hydrotherapy, and posture management are the primary non-medical interventions. A cane supports mobility -- it does not replace the exercise programme. For AS patients, physiotherapy coordination is particularly important: the cane should be selected in conjunction with the physiotherapist managing the exercise programme.
| AS Feature | Cane Implication | Solution |
|---|---|---|
| Forward-stooped posture | Standard height formula inaccurate | Assess in actual walking posture |
| Systemic fatigue | Cane to extend activity before fatigue | Low-vibration wood shaft, anatomic handle |
| Spinal/SI joint pain | Cane provides balance, not direct joint offload | Forward stability point |
| Hip/knee involvement | Standard contralateral placement applies | Per hip or knee protocol |
View the DaiWalk range for adjustable canes that can be precisely fitted in AS walking posture, with the collet mechanism for 0mm lateral play.
