Cartilage Preservation: Can It Maintain Post-Op Dorsiflexion?
One of the most documented postoperative complications of distal metatarsal osteotomies is adhesive capsulodesis that limits dorsiflexion of the first metatarsophalangeal joint (MPJ). When faced with such a post-op complication, one may be able to use a proven cartilage preservation procedure that maintains, if not improves, the first MPJ range of motion.
Austin and Leventon first described the Austin bunionectomy in 1962 and the original procedure has undergone many modifications over the years.1 Each modification has different indications and allows the surgeon a more complete repertoire to help address specific etiologies and pathology when dealing with bunions.
With these modifications, employing the Austin bunionectomy is commonly successful in treating mild to moderate bunions. One of the drawbacks of the distal osteotomy is the risk of decreased first MPJ range of motion secondary to post-op adhesive capsulodesis. The capsulodesis may be due to the rounding of the dorsal medial eminence, which leaves raw bone.
There is very little in the literature that determines the amount of dorsiflexion lost but this condition is mentioned as one of the postoperative sequela.2-9 In addition, there is poor documentation and a wide discrepancy when it comes to measuring techniques for this loss of range of motion. However, there is a consensus that range of motion is affected by distal osteotomies and this is why many podiatric physicians emphasize range of motion exercises as soon as possible after injury.2
A Closer Look At The Cartilage Preservation Procedure
How effective is the cartilage preservation procedure? A study investigating the surgical procedure involved a total of 59 patients from a private practice. We performed the procedure on 50 feet. Two patients had both feet operated on with only one foot subject to the cartilage preservation procedure. The other nine patients did not receive the procedure.
For all the surgeries, we took a traditional approach for bunion surgery. The incision was approximately 6 cm long and medial to the extensor hallucis longus tendon. We performed a linear capsulotomy as well as a lateral release. We removed the medial eminence and performed an Austin-type osteotomy. Using a 0.045 K-wire, we made holes for the Polysorb pins for fixation in a cross wire technique. We measured the sites and cut the pins to fit.
After achieving fixation, we used a sagittal saw to maintain the dorsal medial cartilage by undermining the dorsal medial eminence. This debulks the dorsal medial eminence but keeps the articular cartilage. Then we proceeded to feather the cartilage and bent it down to meet the bone. In order to hold this in place, we performed a capsule closure with the joint in neutral position.10
We performed all additional procedures as needed, including irrigation and re-approximating the capsule. Postoperatively, we placed patients in post-op shoes or casts for three weeks and permitted minimal weightbearing. We had the patients initiate range of motion exercises two days after the procedure. Patients returned for follow-up X-rays in one week.
What Study Results Revealed
As part of the study, we took a post-op dorsiflexion measurement of the first MPJ with the foot 90 degrees to the leg in neutral position. In order to take these measurements, we grasped the proximal phalanx of the hallux and moved it in maximum dorsiflexion with the goniometer on the hallux and compared it to the declination of the first metatarsal. We recorded the measurements at follow-ups ranging from one to seven months post-op with the average follow-up at four months.