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. The average range of motion was 73 degrees of dorsiflexion (ranging from 52 to 100 degrees) in 50 feet. Two patients had bilateral bunion surgery but only one foot underwent the described procedure. One of these patients had 64 degrees of dorsiflexion in the foot that underwent the procedure and 38 degrees of dorsiflexion in the foot that did not undergo the procedure. The other patient had 68 degrees of dorsiflexion with the procedure and 62 degrees without the procedure. In addition to the two patients who had bilateral surgery, nine other patients who did not have the procedure were included in the study for comparison. For those who did not have the procedure, the average range of motion was 58 degrees of dorsiflexion, ranging from 38 to 70 degrees.
How Much Dorsiflexion Is Necessary For Gait?
There is debate in the literature when it comes to the amount of dorsiflexion needed for gait. Root, et. al., state that the minimal amount of dorsiflexion necessary is 65 to 75 degrees at the first MPJ.11 A review of the literature by Nawoczenski, et. al., suggests the range of motion needed for gait is 50 to 90 degrees.12 This discrepancy is due to the fact that there is no standard measurement. One of the inherent flaws in measuring dorsiflexion is the difference of the description of the zero or starting position. The starting position can be in relation to the plantar plane or to the shaft of the first MPJ. In addition, weightbearing measurements are different from those one would take with the patient non-weightbearing. These differences in the starting point and weightbearing measurements make it difficult to compare results from previous studies on first MPJ range of motion. However, when we performed the cartilage preservation technique, the average dorsiflexion measurement was 73 degrees while the average dorsiflexion measurement without the procedure was 58 degrees. This illustrates that the procedure maintains or improves adequate dorsiflexion at the first MPJ. Nawoczenski, et. al., performed a study that helps validate this cartilage preservation technique.12 This study illustrated that the amount of dorsiflexion needed for gait was 42 degrees and that the average measured amount of dorsiflexion with the subject non-weightbearing was 57 degrees. Non-weightbearing measurements were higher than weightbearing measurements, according to the study. These non-weightbearing measurements had high interclass correlation coefficients with a standard error of measurement value of 2.3 degrees or less.12 Those who did not receive the procedure in our study were below Nawoczenski’s recommendation for normal range of motion of the first MPJ. Those patients who did receive the procedure are well above the described normal range of motion.
Our procedure certainly shows that these patients had an increased range of motion of the first MPJ in comparison to the literature.12 This could be due to a different measuring technique. However, when we measured the nine patients who did not undergo the procedure, we utilized the same measurement technique for those who did receive the procedure. We found a considerable difference in first MPJ motion. Granted, some flaws of this study are the lack of preoperative measurements, small sample size and making comparisons to different people who could have had more extensive degeneration of the joint surface. However, this study does validate medial dorsal cartilage preservation as a better procedure than shaving the dorsal medial cartilage. Dr. Mozena is in private practice at the Town Center Foot Clinic in Portland, Ore. He is a Fellow of the American College of Foot and Ankle Surgeons and is board certified in foot and ankle surgery. Dr. Marshall is a second-year podiatric surgical resident. Dr. Burks is a Fellow of the American College of Foot and Ankle Surgeons, and is board certified in foot and ankle surgery. Dr. Burks practices in Little Rock, Ark. For a related article, see “Avascular Necrosis After Bunion Surgery” in the January 2004 issue. Also be sure to check out the archives at www.podiatrytoday.com.
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