How To Treat Hallux Rigidus In Runners
Recently, Nawoczenski, et al., published a detailed analysis of 20 patients who underwent cheilectomy for hallux rigidus and were surveyed six years after the procedure.17 The average dorsiflexion increased by 12 degrees postoperatively but the study patients did not achieve full range for normal walking. Yet the overall range of postoperative dorsiflexion was 30 degrees, which is perhaps considered “normal” for running activities.
Decompression Osteotomy: A Viable Option For Stage II Hallux Rigidus?
Restoring alignment of the first MPJ would seem to be the most straightforward, sensible surgical solution for hallux rigidus. Unfortunately, the published results of these procedures have not validated predictable success in restoring alignment and have not focused on any groups of high performance athletes.
Roukis has evaluated reports of patients undergoing either a Green-Watermann osteotomy or a Youngswick-Austin osteotomy, and concluded there were no significant changes in metatarsus primus elevatus or hallux equinus after either osteotomy.5 Furthermore, patient satisfaction with joint interposition procedures or cheilectomy is similar to joint decompression procedures, according to Roukis, yet these procedures have much less chance for complication than osteotomies of the first metatarsal.
The primary concern with first metatarsal osteotomies is potential serious complications for the running athlete. Since these procedures are designed to shorten the first metatarsal and decompress the joint, the risk of transfer metatarsalgia is significant for all patients. For running athletes, whose peak forefoot forces are amplified threefold in comparison to when they walk, increased plantar pressure under the central metatarsals can lead to capsulitis, predislocation syndrome and stress fracture of the metatarsals.
When I perform an osteotomy for relief of hallux rigidus, I make certain that the first metatarsal is either longer than the second or that there is no significant increased pressure under the second metatarsal in comparison to a preoperative measurement with a Mat Scan® analysis. The best osteotomy to restore function of the first MPJ is the modified Hohman procedure, which can maximize plantarflexion with minimal shortening.18
What About Implants For Hallux Rigidus?
Joint implants have been advocated for over 40 years for the treatment of hallux rigidus. However, there is currently no study documenting the long-term performance of any first MPJ prosthesis in running athletes. However, many manufacturers will advocate use of these implants for younger patients with active lifestyles that include vigorous running.
While runners may use less range of motion in the first MPJ than walkers, the magnitude of forces in running across this important joint cannot be overestimated. Until recently, it was not possible to measure joint moments within the foot during walking or running. Now, with multi-segment foot modeling, we will soon learn more about the forces transmitted within the medial column of the foot and the first MPJ.
For now, we can look at the ankle and compare the differences in forces that occur in walking versus running. Many investigators have studied forces or moments that occur at the ankle joint, and have found that there is an approximate 10-fold increase of internal joint moment during running as opposed to walking. This means that the internal structure of the joint (i.e. the articular cartilage) is subjected to a 10-fold increase of stress-strain during running activity.
The first MPJ is actually more complicated than the ankle since there is considerable frontal plane movement of the first metatarsal coupled with dorsiflexion of the hallux. No implant for the great toe joint is designed to allow this coupled movement in the same magnitude. Thus far, measurements have been in vivo and no implant has been tested under the vigorous conditions of running.
Given the lack of evidence of favorable outcomes with prosthetic joint implants for the treatment of hallux rigidus in running athletes, podiatrists should be cautious about using these devices in this patient population. Furthermore, when an implant fails, the options for salvage may end the career of the running athlete.