Metatarsal Head Resurfacing: Does It Have A Place In Treating Hallux Limitus/Rigidus?

By Bob Baravarian, DPM, and Jonathon Thompson, DPM

     Hallux limitus occurs when a patient has decreased sagittal plane dorsiflexion of the great toe with the foot in a weightbearing or simulated weightbearing loaded position that is usually associated with a progressive, arthritic and painful condition of the first metatarsophalangeal joint (MPJ).      Functional hallux limitus is described as limited joint mobility with the foot in a loaded position versus normal range of motion in an unloaded position. Hallux rigidus can be defined as elimination of range of motion at the joint, and usually results from end-stage ankylosing of hallux limitus. According to the literature, normal gait requires approximately 60 to 80 degrees of hallux dorsiflexion. While one could argue this concept since the foot has several compensatory mechanisms that could lower this value, it does give a benchmark for diagnosis, treatment and surgery.      For completeness, we will mention but not expand on several etiologies that predispose hallux limitus. The many causative factors include but are not limited to the following: posttraumatic, microtraumatic as with repetitive trauma, an elongated or short first metatarsal, first ray hypermobility, first metatarsal primus elevatus and pes-plano-valgus deformities. Diagnosing each patient’s etiology is important and will better allow you to treat the patient whether it is with conservative therapies or surgery. One must address each of these factors, especially when determining the appropriate surgical procedure to recommend to the patient.      Upon the physical examination, one will see decreased hallux range of motion with tenderness at both mid- and end range of motion, crepitus, first ray hypermobility, associated pinch callus (tyloma) at the medial hallux, transfer metatarsalgia with or without lesions, flatfeet, posterior tibial tendon weakness, ankle equinus and first ray elevatus. There are also palpable dorsal, lateral and medial osseous prominences.

A Guide To Conservative Options

     Podiatrists can treat hallux limitus conservatively as well as surgically. As with most foot pathologies, it is recommended that one exhaust all conservative modalities prior to surgical intervention. Conservative modalities include the following:      • Shoe gear modification. This includes extra-depth, wide, stiff or rigid soled shoes.      • Antiinflammatories. This includes oral or intraarticular injections.      • Orthotic therapy. One may use a prescription functional insert with a first ray cutout or depression to improve functionality of the joint complex by promoting first metatarsal plantarflexion. Alternatively, one may consider a Morton’s extension to jam or completely lock the first MPJ. In our experience, it can sometimes be more difficult than it seems to prescribe the proper orthotic. There is a trial and error period when it comes to finding the best orthotic modifications for your patients.      • Modification of activities. As stated previously, this is a progressive and destructive deformity that unfortunately sometimes requires surgical intervention.

When You Need To Address Mild Or Moderate Hallux Limitus With Surgery

     When addressing hallux limitus as a surgical entity, one must incorporate both clinical and radiographic evaluation. It is our contention that one can classify hallux limitus as mild, moderate and severe. (Surgeons must also keep a global view and be able to recognize compound pathologies such as pes plano valgus deformity or possible gastrocsoleus equinus that one may need to address surgically prior to or in conjunction with the primary procedure.)      In regard to mild hallux limitus, these patients have some decreased range of motion with some tenderness and minimal joint space narrowing with minimal osteophytic growths in the presence of a stable first ray. For these patients, one may usually consider a typical cheilectomy. However, if the condition is associated with unstable and hypermobile first ray, we recommend performing a metatarsal cuneiform arthrodesis in addition to the cheilectomy in order to address the etiologic force.      Moderate hallux limitus involves further decreased hallux range of motion with increased tenderness, possible crepitus, moderate joint space narrowing and large osteophytic growths dorsal, lateral and/or medial of the first metatarsal head. One may also see these osteophytic growths at the base of the proximal phalanx. This condition usually requires a “more aggressive” cheilectomy that incorporates excising the dorsal one-third of the articular surface of the first metatarsal head as well as removal of osteophytes of the corresponding base of the proximal phalanx.      We have had good success with this aggressive cheilectomy. The secret to a good cheilectomy is performing an intraoperative test by pushing up and loading the first metatarsal head, and matching the corresponding base of the proximal phalanx to determine the amount of bone to resect from the first metatarsal. Other procedures that one should consider are shortening or plantarflexory osteotomies in the presence of an elevated or elongated first metatarsal.

Is There Another Option For Hallux Rigidus?

     As hallux limitus progresses, the deformity becomes severe and the joint becomes ankylosed and rigid. For our purposes, this can be better described as hallux rigidus. At this point, there is minimal or no range of motion, severe palpable osteophytic growth and severe arthritic changes of the joint. Surgically speaking, most authors recommend a joint destructive type of procedure that includes Keller arthroplasty, first MPJ arthrodesis, total or hemi-implants. We are in favor of an arthrodesis procedure when possible and the patient is amenable.      If an arthrodesis procedure is contraindicated, we recommend a viable alternative to the traditional implants in the form of the Arthrosurface first metatarsal head implant. One would perform this procedure with a simple cheilectomy and resection of osteophytic growths. It is relatively easy to perform and does not require as much resection or loss of bone as the Keller arthroplasty or total/hemi-implants. By resurfacing the metatarsal head portion of the joint, we are able to save the tendon attachments to the base of the great toe and preserve the option for future fusion as necessary.      The fitted implant allows for immediate loading. This facilitates improved recovery and rapid therapy to limit scar formation, and decreases the risk of stiffness. One would remove the osteophytic spurring from the surrounding joint after placing the implant. If there is severe degeneration of the base of the great toe, we have found that tucking a segment of the dorsal capsule into the joint and attaching it with anchors to the base of the great toe helps preserve motion and allows for a spacer in the joint.

In Conclusion

     Although fusion of the first metatarsophalangeal joint is an excellent option for hallux rigidus/limitus with severe articular damage, the additional choice of a partial joint replacement provides a viable alternative for those who do not wish to have a fusion. Our results to date have been excellent and we have found the Arthrosurface first metatarsal head implant to be an excellent choice for severe hallux limitus cases.      Dr. Baravarian is an Assistant Clinical Professor at UCLA School of Medicine. He is the Chief of Foot and Ankle Surgery at Santa Monica UCLA Medical Center and Orthopedic Hospital, and is the Director of the University Foot and Ankle Institute in Los Angeles.      Dr. Thompson is an Associate at the University Foot and Ankle Institute. He is a Clinical Instructor in the VA Greater Los Angeles Healthcare System.

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