- Bunion Basics
- For Doctors
“Syndesmosis” is a normal anatomical structure in human body to connect and stabilize two parallel long bones. Syndesmosis procedure is intended to produce this connecting structure for bunion correction. The syndesmosis concept has been evolved from the understanding that the true cause of bunion deformity lies in the malfunctioning of the ligaments rather than any real bone deformities. If bones are normal and not at fault, then no bone should ever need be broken except probably in very rare occasions. The non-bone-breaking syndesmosis procedure aims to re-align and re-stabilize the displaced but normal bones of the bunion foot. It does so by tying the displaced and loose first metatarsal bone to the adjacent second metatarsal bone and then also by creating a syndesmosis fibrous bridge to connect and stabilize it to the second metatarsal bone to prevent future deformity recurrence.
The problem of bunion condition is very much similar to the famous Leaning Tower of Pisa, because both of them suffer the same problem of instability and leaning displacement. Bunion deformity is also caused by leaning of the first metatarsal which is the (yellow) long bone behind the big toe. The structures of both the Tower of Pisa and the first metatarsal bone are normal and unchanged from the day they were created. They lean only because their supporting structures, namely the foundation of the Tower and ligaments of the bone respectively, have failed on them. If the Tower were ever broken and shifted to make it look straighter, many would seriously be concerned by the fact that the Tower will be irrevocably damaged and may even still continue to lean because its weak foundation problem has never been addressed. Similarly, break-n-shift of the normal first metatarsal bone may lead to questionable form and function consequences. Similarly, its re-displacement and bunion deformity may still happen due to its instability issue was not addressed at all, either.
Since there is no bone-breaking involved, there is usually much less pain. Walking is allowed any time after surgery. Crutches are not necessary but recommended for outdoor walking.
Protective footwear has to be worn for 3 months until the syndesmosis connecting bridge is mostly completed. During the same period walking is not a problem but needs to be restricted to less than 5,000 steps a day if possible and at a slower pace also.
Big toe is the most important of all toes to propel body forward. A bunion deformity would damage normal function of big toe and impose a compensatory gait of shifting the walking force from inner side of the forefoot to its outer side. This is one of the reasons for the callus formations under the mid and outer part of forefoot and also clawing deformity of the lesser toes.
In order to detect and analyze abnormal gaits objectively, a computerized function study system by F-Scan® was installed in our Bunion Center since 2005. The precise pressure and force exerted on the sole in walking can be accurately demonstrated and documented. It helps confirm function abnormalities of the foot and evaluate any true function improvement by surgery.
The medical engineering department of Polytechnic University of Hong Kong has helped analyze the function scan results of our patients and confirmed statistically significant improvement in function of both big toe and foot after syndesmosis procedure.
As big toe is normally responsible for up to 80% of power of all toes in pushing our body forward, a normal function study should show red color under the big toe.
In the case of bunion deformity, the function/power of big toe is diminished. Thus the typical finding is the much reduced (blue color) force under the big toe and shifting of the weight-bearing force towards the outer side of the forefoot such as seen under the mid metatarsal region (red). It’s the reason for callus and pain in this area.
Complication is always a possibility for any surgical undertaking, no matter how small the surgery may be, how skillful the surgeon is and even how cooperative the patient can be. However, more extensive surgeries have in general greater risk in developing complications.
Dr. Wu ' s bunion surgery is less traumatic because it does not need to break any bones at all, but it still can have its share of possible complications, albeit they are relatively fewer and milder in comparison to bone-breaking bunion surgeries.
The following is a list of known complications that have happened in our past 1,600 cases over 20 years.
1. Wound infection
Wound infection can be acquired during or after surgery. Our infection rate has fortunately been very low and < 0.5 %.
2. Sensory nerve injury
Numbness can happen to any surgical wound due to small sensory nerve injury. Our patients may also experience partial or complete numbness of a small area on top of their big toes in <5% of cases. Such numbness is not usually noticeable and would not affect normal walking or running. Rarely such nerve injury may also cause pain in the area.
3. Deformity recurrence
Excessive walking during the first 3 post-operative months can loosen the internal stabilizing sutures and cause some loss of initial deformity correction. We have different ways to help protect those sutures for early walking, but limited and slow-paced walking is still their best protection. Much encouragingly, long term bunion recurrence has been rare of Dr. Wu’s >1,600 feet up to 25 years once the syndesmosis connective ligament bridge is fully consolidated by 6 months after surgery regardless of activities and shoes.
4. Stiff big toe joint
Big toe joint can normally bend upwards 70-90° for fast walking, running and hi-heel shoes. It can become stiff after bunion surgery. However, it happens uncommonly after syndesmosis procedure because the simple exercises to prevent it from happening can be started immediately after surgery without physiotherapy.
Arthritis (articular cartilage damage) in big toe joint is usually pre-existing due to prolonged and severe deformity. Fortunately, few such patients have problems with it after syndesmosis procedure, due possibly to its minimal traumatic nature and maximal joint alignment restoration.
Contrary to general belief, the non-bone-breaking syndesmosis procedure is very powerful and able to correct bunion deformity of all severities. It can even over-correct. Usually, slight adjustment in post-operative management can help remedy the situation. Seldom may the internal stabilizing sutures need be surgically released.
7. Stress fracture
Stress/fatigue fracture of the second metatarsal can happen due to excessive walking and bone erosion by its binding sutures. This complication has mostly been minimized since our introduction of a small protective steel plate. But reduced walking is still important to avoid this complication from happening at all.
If you have any question about any of these possible complications, please feel free to discuss them with us.