summary Hallux rigidus is a common foot condition characterized by pain and loss of motion of the 1st MTP joint in adults due to degenerative arthritis. Diagnosis is made with orthogonal radiographs of the foot that may show joint space narrowing and dorsal osteophytes of the 1st MTP joint. Treatment of early disease consists of a trial of nonoperative management with a Morton's extension orthotic. Operative management is indicated for higher grade disease and varies depending on chronicity of symptoms and severity of osteoarthritis. Epidemiology Incidence 2.5% of patients older than 50 years most common location of osteoarthritis in the foot Demographics females > males (2:1) most commonly noted in the 5th and 6th decade of life Risk factors history of trauma to the 1st MTP joint noted in ~80% of patients with unilateral disease Etiology Pathophysiology primary etiology unknown acute trauma and repetitive microtrauma predispose to arthritic changes pathoanatomy osteophyte formation and degeneration of the cartilage occur dorsally in early stages and progress to involve the entire joint anatomic variations of first metatarsal may play a role in arthritic predisposition metatarsus adductus long first metatarsal Associated conditions orthopedic conditions sesamoid arthritis medical conditions gout rheumatoid arthritis Anatomy Osteology first metatarsal shortest and widest Neurovascular medial branch of the medial dorsal cutaneous nerve overlies 1st MTP joint can become irritated by dorsal osteophytes Biomechanics the first MTPJ carries up to ~120% of an individual's body weight with each step Classification Coughlin and Shurnas Classification Exam findings Radiographic findings Grade 0 Stiffness Normal Grade 1 Mild pain at extremes of motion Mild dorsal osteophyte, normal joint space Grade 2 Moderate pain with range of motion, increasingly more constant Moderate dorsal osteophyte,<50% joint space narrowing Grade 3 Significant stiffness, pain at extreme ROM, no pain at mid-range Severe dorsal osteophyte, >50% joint space narrowing Grade 4 Significant stiffness, pain at extreme ROM, pain at mid-range of motion Same as grade III Presentation Symptoms first ray and 1st MTP joint pain worse with push off or lift-off phase of gait dorsal medial foot paresthesia due to dorsal osteophytes and compression of medial dorsal cutaneous nerve transfer metatarsalgia Physical exam inspection swelling of the 1st MTP joint dorsal prominence over the 1st MTP joint (due to dorsal osteophytes) severe disease may present with hyperextension deformity motion limited dorsiflexion pain with terminal dorsiflexion as disease progresses, patient develops pain throughout arc of motion inverted gait neurovascular decreased push-off strength decreased sensation over distal aspect of medial dorsal foot provocative tests pain with grind test indicative of severe disease with central chondral wear Imaging Radiographs recommended views AP, lateral, sesamoid and oblique views of the foot findings dorsal osteophytes joint space narrowing subchondral sclerosis and cysts CT indications suspected osteochondral cysts with normal radiographs can better characterize mild osteoarthritis Treatment Nonoperative NSAIDS, activity modification, intra-articular injections & Morton's extension orthotic indications grade 0 and 1 disease outcomes good short and mid-term pain relief noted in low-grade disease Operative dorsal cheilectomy indications grade 1 and 2 disease select patients with grade 3 disease with primarily pain with terminal dorsiflexion shoe wear irritation from dorsal prominence and pain (ideal candidate) contraindications when pain located in the mid-range of the joint during passive motion outcomes pain with terminal dorsiflexion is an indicator of good results with dorsal cheilectomy Moberg procedure (dorsal closing wedge osteotomy of the proximal phalanx) indications runners with reduced dorsiflexion (60° is needed to run) failure of cheilectomy to provide at least 30 to 40 degrees of motion Keller Procedure (resection arthroplasty) indications elderly, low demand patients with significant joint degeneration and loss of motion that allows for rapid rehabilitation contraindications patients with pre-existing rigid hyperextension deformity of 1st MTP joint outcomes good results have been noted in low demand elderly patients significant risk of joint instability for younger and more active patients MTP joint arthroplasty indications grade 3 and 4 disease for patients who wish to preserve joint motion contraindications active infection insufficient bone stock hallux sesamoid arthritis outcomes silicone implants may have a good short term satisfaction rate but have high long term failure rate osteolysis and synovitis cause mid to long term pain and joint destruction current implant designs with 80-90% survival rates at ~5 years no difference in functional outcomes, complications or satisfaction rates between hemiarthroplasty and total joint arthroplasty MTP joint arthrodesis indications grade 3 and 4 disease (significant joint arthritis) most common procedure for hallux rigidus outcomes 90-100% fusion rate 95% satisfaction rate MTP joint arthrodesis with structural bone graft indications for structural bone graft 1st MT shortening that cannot be adequately rebalanced with a lesser metatarsal osteotomy (usually shortening > 5 mm) most commonly seen with failed MTP arthroplasty significant proximal phalanx bone loss with inadequate remaining bone for fixation without compromising IP joint, 1st MT shortening with loss of medial support of the 2nd toe predisposing to varus at the 2nd MTP joint. Techniques NSAIDS, activity modification, intra-articular injections & Morton's extension orthotic activity modifications avoid activities that lead to excessive great toe dorsiflexion intra-articular injections both corticosteroid and sodium hyalurate injections have been shown to significantly improve pain scores at 4 and 8 week followup in low-grade disease types of orthotics Morton's extension with stiff foot plate is the mainstay of treatment extends past the first MTP joint providing a stiff construct that allows minimal dorsiflexion at the articular surface stiff sole shoe and shoe box stretching may also be used Dorsal cheilectomy technique remove up to 30% of the dorsal aspect of the metatarsal head along with dorsal osteophyte resection resection > 30% may lead to joint subluxation the goal of surgery is to obtain 70-90% of dorsiflexion intraoperatively Moberg procedure (dorsal closing wedge osteotomy of the proximal phalanx) technique increases dorsiflexion by decreasing the plantar flexion arc of motion Keller Procedure (resection arthroplasty) technique involves removing the base of the first proximal phalanx interposition risk of hyperextension (cock-up deformity), weakness with push-off, and transfer metatarsalgia (decreased with capsular interposition) MTP joint arthroplasty technique hemiarthroplasty unipolar implant designed to replace the articular surface of metatarsal head or proximal phalanx base benefits compared to total joint maintains length of first ray easier conversion to arthrodesis if necessary total joint arthroplasty first and 2nd generation silastic implants (silicone rubber) high failure rate (~60%) with silicone wear, osteolysis and implant failure third generation metal implants with press-fit fixation fourth generation metal implants with threaded stem fixation MTP joint arthrodesis technique compression and internal fixation can be achieved with wires, pins, lag screws, dual crossed screws and plates dorsal plate with compression screw is biomechanically strongest construct preferred surgical alignment 10 to 15 degrees of valgus in relation to the metatarsal shaft 15 degrees of dorsiflexion in relation to the floor Best way to assess this intraoperatively is with foot plate to simulate weight bearing with 4-8mm of clearance of toe from plate complications fusion in excessive dorsiflexion causes pain at tip of the toe, over the IP joint, and under the 1st metatarsal with excessive dorsiflexion fusion in excessive plantar flexion causes increased pressure at the tip of the toe fusion in excessive valgus increases the risk of IP joint degeneration MTP joint arthrodesis with structural bone graft technique structural bone graft used to restore metatarsal length tricortical iliac crest allograft most commonly used Complications Failed arthroplasty risk factors early generation implants (specially silicone implants) treatment implant resection, synovectomy if there is isolated great toe pain implant resection, bone grafting, and arthrodesis if there is great toe pain with lesser toe metatarsalgia Nonunion incidence 5-10% after arthrodesis 33% of patients with a nonunion are asymptomatic treatment revision arthrodesis with bone grafting First MTP joint cock-up deformity risk factors keller resection arthroplasty treatment first MTP joint arthrodesis Hallux IP joint osteoarthritis incidence 15% of patients following hallux MTP joint arthrodesis risk factors hallux MTP joint arthrodesis treatment usually asymptomatic Prognosis Natural history of disease radiographic progression may not always correlate with symptom progression Return to activity 96% of patient satisfaction rate after first MTP joint arthrodesis with respect to post-operative activity level