First MPJ Arthrodesis: What The Evidence Reveals
To solve this problem, double-stem silicone implants with titanium grommets were designed.3,24 Despite these technical improvements, the implants were still susceptible to these stresses and silicone debris leading to foreign body reactions, synovitis and the persistence of bony erosion.3,25 Total joint replacement via two-component metallic hemi-implants with non-constrained articulations yielded better results.3,26 However, these implants still had problems such as subluxation, infection and early loosening.
Once implant failure occurs, the subsequent conversion to arthrodesis becomes more complex. This is due to bone loss created by the original implant insertion. When there is associated osteolysis, complex bone grafting is required.27-29
A recent report by Brewster compared the functional results of total joint replacement versus arthrodesis.30 This literature review showed significant improvement in results from pre- to post-op status in both groups. Median scores were 83/100 for total joint replacement versus 82/100 for the arthrodesis group. However, the revision rate for the total joint replacement group was 7 percent in comparison to 0 percent for the arthrodesis group.
Several studies have shown that the first MPJ arthrodesis is a predictable and excellent option providing high success rates in pain relief and restoration of function. However, this procedure is not without its disadvantages. Researchers have documented loss of motion, shoe wear problems, a long recovery period, metatarsalgia, difficulty kneeling, hardware irritation, delayed unions and non-union as problems.7 Other concerns include having to be non-weightbearing for up to six weeks.
The pursuit of successful joint replacements is due to the biomechanical advantages that a mobile hallux offers.30 The first MPJ arthrodesis has consistently been the gold standard in the orthopedic community due to its ability to relieve pain, achieve good cosmesis and alignment, and maintain the medial column and toe length. Ultimately, the patient retains restoration of normal foot function but at the sacrifice of joint movement.30 This is often a major concern to the patient.
Despite this, there has been high patient satisfaction with first MPJ arthrodesis. Sung and coworkers showed a union rate of 94.8 percent (55 of 58 patients).31 In a prospective study of 49 patients who underwent arthrodesis, Goucher and Coughlin noted a 96 percent satisfaction rate with a 92 percent union rate.32 Significant improvements occurred in both pain and AOFAS clinical rating scores.
Pertinent Insights On Arthrodesis Technique
One may prepare the first MPJ surface with a transverse osteotomy of the first metatarsal head and base of the proximal phalanx. This is usually an option in severe hallux abducto valgus correction, in which dislocation of the joint requires shortening for realignment. In most conditions, this technique makes it difficult to obtain desired amounts of valgus/varus, dorsiflexion/plantarflexion and adduction/abduction of the hallux. Adjusting the alignment is variable and can result in further bone resection. This can result in first ray shortening, causing an undesired cosmetic and pathologic side effect.1