How To Treat Osteoarthritis Of The First MTPJ
Hallux limitus/rigidus is defined as a degenerative arthrosis of the first metatarsophalangeal joint (MTPJ) which is characterized by a decrease in the MTPJ range of motion and an eventual lack of motion.1 Treatment for this condition is a frequently discussed topic at podiatric conferences. When it comes to the stages of osteoarthritis in the MTPJ, one may consider performing joint preservation or joint destructive procedures. Joint preservation procedures include cheilectomy procedures, soft tissue correction and distal/proximal osteotomies as indicated for osseous correction. With more advanced stage osteoarthritic changes, you would consider a joint destructive procedure such as a Keller arthroplasty, a joint replacement or an arthrodesis. One should consider structural variables such as soft tissue contractures, hallux deviation, metatarsus primus elevatus, the metatarsal parabola and the quality of the bone density. External influencing factors will include the patient’s shoe type, work environment, precipitating pain and his or her recreational activities. Understanding The Importance Of Appropriate Patient Selection In regard to the implant arthroplasty, we usually reserve this as an end-stage procedure in non-salvageable joint disease with the MTPJ. Keep in mind that the patient’s activity alone may play a roll in selecting an implant arthroplasty over a joint fusion.2 Granted, one must weigh the merits of using a hemi-toe implant versus a total joint implant, which may be a single stemmed component or a two-component articulated joint replacement. I have found that metallic hemi-implants offer significant benefits over silastic devices. These benefits include the absence of plastic deformation; fatigue fracture due to stress loading over time; and microfragmentation and medullary shearing at the bone interface. There is no shortening of the first metatarsal so you are able to preserve the weightbearing distribution. I prefer to perform a hemi-toe implant arthroplasty with the LPT Titanium Hemi-Toe Implant (Wright Medical). This procedure is beneficial for the patient who has an advanced stage arthritic first MTPJ with a lack of joint space, provided that you have the ability to restore the contour of the first metatarsal head. Also be aware that dorsal and marginal spurs can form at the first metatarsal head and restrict range of motion. You can resect these spurs without performing a partial arthroplasty. For the best long-term results, these patients should have the following criteria: • good bone stock to allow for proper seating of the implant; • normal alignment of the first metatarsal in the transverse and sagittal plane; • normal to short first metatarsal; • a non-arthritic metatarsal sesamoid complex; and • the absence of a metabolic arthritis process.2 Keep in mind that any structural malalignments of the first metatarsal that are not addressed may lead to complications and abnormal stresses on the implant. This can increase the incidence of implant failure over time. Implant failure may also be precipitated by abnormal pronation that induces a functional hallux limitus. Step-By-Step Insights On Performing The Hemi-Toe Implant Arthroplasty To begin this procedure, you would start with a standard dorsal medial incisional approach. This not only facilitates joint exposure but allows you to preserve the joint capsule, which facilitates remodeling of the first metatarsal head including the resection of lateral and dorsal bone spurs. It is essential to release and mobilize the medial, lateral and plantar fibrous adhesions for intraoperative joint mobilization. Doing so enables you to use the instrumentation for placing the implant. I find the McGlamry elevator invaluable in performing the soft tissue release and minimizing the amount of soft tissue dissection and trauma to that area. A good release will increase the first metatarsophalangeal joint space and allow for better exposure for soft tissue reflection at the base of the phalanx as you prepare for bone resection. Proceed to perform a 5-mm to 10-mm resection at the base of the proximal phalanx when you release the capsular attachments. Exercise care in the area under the phalanx base so you can prevent a possible release of the flexor brevis tendon. I perform conservative but adequate resection that maintains hallux length and minimizes damage to the flexor tendon.