In a healthy adult undergoing thumb interphalangeal (IP) joint arthrodesis, what is the expected time to radiographic union and the recommended postoperative immobilization, rehabilitation schedule, and factors influencing healing?

Thumb Interphalangeal Joint Arthrodesis: Postoperative Timeline and Management

Optimal Fusion Angle

Fuse the thumb IP joint at 15° to 30° of flexion, with 15° being the most functional angle for both dominant and non-dominant hands across activities of daily living. 1, 2

• For patients with thumb carpometacarpal osteoarthritis specifically, 15° is the preferred angle, while 45° should be avoided as it significantly impairs precision tasks and pinch strength 2
• The 15° angle optimizes both power tasks (grip strength) and precision tasks (writing, buttoning) while maintaining patient satisfaction closest to baseline function 1
• Angles of 0° to 30° are acceptable, but 15° provides the best balance for the dominant hand across all functional categories 1

Expected Time to Radiographic Union

Radiographic fusion of the thumb IP joint occurs at an average of 8-12 weeks postoperatively. 3

• Distal interphalangeal joints (including thumb IP) demonstrate solid osseous union at approximately 8 weeks when using compression screw fixation 3
• Thumb IP joints specifically may take slightly longer, averaging 12 weeks to radiographic fusion 3
• When using intramedullary implants, the mean healing time is 9.1 weeks 4
• Fusion rates are high (95%) regardless of fixation method (crossed K-wires, compression screws, or intramedullary implants), with similar nonunion rates across techniques 5, 3

Postoperative Immobilization Protocol

Maintain rigid immobilization for 6-8 weeks until radiographic evidence of fusion is confirmed. 3

• Remove K-wires at 4-5 weeks when fracture union is confirmed on radiographs 6
• Compression screws do not require removal after fusion heals, allowing earlier mobilization compared to K-wire techniques 3
• Uninterrupted immobilization is essential—even brief splint removal can restart the healing timeline 7

Rehabilitation Schedule

Begin active range of motion exercises of the MCP and proximal joints immediately while keeping the IP joint immobilized. 7

• Start active finger motion exercises of the PIP and MCP joints immediately postoperatively to prevent stiffness in adjacent joints 7
• The IP joint itself remains splinted throughout the immobilization period 7
• After confirmed radiographic union (8-12 weeks), the IP joint is permanently fused and requires no further rehabilitation 3
• Home exercise programs moving adjacent fingers through complete range of motion are effective during the immobilization period 6

Factors Influencing Healing and Complications

Major risk factors for nonunion include inadequate bone stock, inadequate bone resection, premature pin removal, and infection. 5

• The overall nonunion rate is approximately 5-12% across all fixation techniques 5, 3
• 20% of fusions experience major complications (nonunion, malunion, deep infection, osteomyelitis) 5
• Minor complications occur in 16% of cases (dorsal skin necrosis, cold intolerance, PIP stiffness, paresthesias, superficial infection, prominent hardware) 5
• Of nonunions that occur, approximately 62% remain pain-free and may not require revision 5
• Infection requiring implant removal occurs in approximately 1% of cases when using intramedullary implants 4

Critical Monitoring Points

Patients should be re-evaluated immediately if unremitting pain develops during the immobilization period. 7

• Unremitting pain warrants assessment for inadequate fixation, infection, or hardware complications 6
• Obtain radiographs at regular intervals (typically 2 weeks, 6 weeks, and 12 weeks) to monitor healing progression 3
• If nonunion occurs and is symptomatic, revision arthrodesis is successful in most cases (approximately 86% of attempted revisions achieve fusion) 5

Pain Management During Recovery

Use topical NSAIDs preferentially over oral NSAIDs for safety, with oral NSAIDs reserved for limited duration if needed. 7

• Ice therapy provides effective short-term pain relief during the acute postoperative phase 7
• Apply ice-water mixture for 10-20 minutes with a thin towel barrier to reduce swelling 7