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This is the clinical evidence summary written for health professionals. It is technical, and it lists the research this page was built from. You do not need to read it to understand your treatment or to make a decision about it.

Overview

• Differentiating a true boutonniere deformity from a pseudoboutonniere injury is critical in determining clinical management [1].
• An understanding of the anatomy, clinical presentation, treatment options, and expected outcomes is crucial for optimal treatment of posttraumatic boutonnière and swan neck deformities [2].
• Early treatment of central slip injuries can prevent the deformity [3].
• The natural history of the boutonnière deformity in rheumatoid arthritis is outlined in the literature [5].
• Chronic boutonniere deformity will respond to relative motion flexion splinting if serial casting can place the proximal interphalangeal joint in less than -20° extension [6].
• For chronic boutonniere deformity, the patient must actively use the hand in a relative motion flexion orthosis for 3 months to recover flexion [6].
• Serial casting for adequate extension followed by 3 months of relative motion flexion orthotic use should be attempted prior to surgical intervention for chronic boutonniere deformity [4].
• Extensor tenotomy to correct a boutonnière deformity of long standing markedly lessened disability with restoration of flexion of the distal joint [10].
• Transection of the terminal extensor tendon is a useful procedure for salvage of the boutonniere deformity [13].
• The Y-shaped tendon graft can be a useful procedure for the correction of chronic boutonniere deformity [7].
• In a patient series, the Y-shaped tendon graft provided good or excellent results in 16 of 18 patients for chronic boutonniere deformity [7].
• The cross-lateral band reconstruction technique using palmaris longus autograft is a treatment option with satisfactory results for chronic boutonniere deformity when the lateral bands are deficient or damaged [9].
• Congenital boutonniere deformity is understood as various embryonic developmental failures [8].
• Central slip reconstruction is a reliable surgical option for the congenital form of boutonniere deformity [8].

Anatomy & Pathophysiology

Extensor Mechanism Anatomy

• The extensor mechanism of the finger at the level of the proximal interphalangeal (PIP) joint consists of both intrinsic and extrinsic contributions [19].
• The extensor tendon entering the digit is the continuation of the extensor digitorum communis (EDC), with contributions from the extensor indicis proprius in the index finger and the extensor digiti quinti in the small finger [19].
• In 30% of cases, the EDC has a separate insertion into the base of the proximal phalanx, but extension of the metacarpophalangeal (MP) joint most often occurs through the pull of the sagittal bands [19].
• The deep head of each dorsal interosseous muscle forms a lateral tendon, or lateral band, at the level of the MP joint [25].
• At the level of the middle of the proximal phalanx, transverse fibers arch dorsally from each lateral band to join over the dorsum of the finger, flexing the proximal phalanx [25].
• Oblique fibers (spiral fibers) from the lateral bands sweep over the distal third of the proximal phalanx to insert onto the lateral tubercles at the base of the middle phalanx, extending the middle phalanx at the PIP joint [25].
• The lateral bands are joined by the lateral slips of the extensor tendon to form the conjoined lateral band [25].
• The two conjoined lateral bands unite at the distal third of the middle phalanx to form the terminal tendon, which inserts at the base of the distal phalanx to extend it [25].
• The volar interossei form the ulnar lateral band of the index finger and the radial lateral band of the ring and little fingers [25].
• The flexor digiti quinti brevis is structurally and functionally similar to the deep head of the dorsal interossei, forming the ulnar lateral band of the little finger [25].

Pathomechanics and Injury

• A boutonniere deformity requires subluxation of the lateral bands volar to the axis of rotation of the PIP joint [15].
• Damage to the central slip alone does not cause a boutonniere deformity [15].
• A boutonniere deformity occurs only when the central slip, triangular ligament, and transverse and oblique fibers of the interosseous hood are all damaged [15].
• Detachment of the central slip from the middle phalanx produces a decrease in extension of the PIP joint [15].
• When the transverse and oblique fibers of the interosseous hood are divided in addition to the central slip, extension at the PIP joint is further decreased [15].
• Extension of the PIP joint decreases as structures are progressively damaged [40].
• Injury to the extensor mechanism, specifically the central slip, can lead to snapping or catching at the PIP joint [39].
• In irreducible volar dislocations of the PIP joint caused by interposition of the intact central slip, the extensor mechanism is displaced rather than disrupted [47].
• Long-standing complex pathophysiological changes in boutonniere deformity make full correction impossible, resulting in an inevitable few degrees of PIP joint extension deficit [46].

Classification

• The boutonniere deformity requires subluxation of the lateral bands volar to the axis of rotation of the PIP joint [15].
• Combined injury of the central slip, triangular ligament, and transverse and oblique fibers of the interosseous hood causes a boutonniere deformity [15].
• Anterior dislocation of the proximal interphalangeal joint is associated with ruptures of the central slip of the extensor mechanism [18].
• Anterior dislocation of the proximal interphalangeal joint results in boutonnière deformity unless repaired [18].
• The prevalence of boutonnière deformity without rheumatoid arthritis or trauma is approximately 13% [11].

Clinical Presentation

• A swan-neck or boutonniere deformity occurs in approximately half of patients with rheumatoid arthritis [16].
• The incidence of uncorrectable swan-neck and boutonniere deformities is estimated to be between 8% and 16% during the first 2 years after the onset of systemic disease [16].
• The prevalence of finger deformities in patients with established rheumatoid arthritis is approximately 36% for boutonniere deformities [16].
• The cause of boutonniere deformity in rheumatoid arthritis is chronic synovitis of the proximal interphalangeal joint [16].
• Boutonniere deformities can be painful and can impair finger and hand function significantly [16].
• A boutonniere deformity requires subluxation of the lateral bands volar to the axis of rotation of the proximal interphalangeal joint [15].
• Detachment of the central slip from the middle phalanx produces a decrease in extension of the proximal interphalangeal joint [15].
• Division of the central slip leads to loss of extension at the proximal interphalangeal joint [15].

Investigations

• A careful physical examination is essential to direct care and future testing if indicated [22].
• Diagnostic tests such as imaging and serum laboratory studies are useful in the determination of pathology but can be expensive, time consuming, and often nonspecific [22].
• The extensor mechanism of the finger at the level of the PIP joint consists of both intrinsic and extrinsic contributions [19].
• The extensor tendon that enters the digit is the continuation of the extensor digitorum communis (EDC) and in the index and small fingers the extensor indicis proprius and extensor digiti quinti, respectively [19].
• Thirty percent of the time the EDC has a separate insertion into the base of the proximal phalanx [19].
• Extension of the metacarpophalangeal (MP) joint most of the time occurs through the pull of the sagittal bands [19].
• A finite element model was developed and validated that successfully replicated the behavior of the digit under specific scenarios, including the extension of the DIP joint during Elson's test observed in cadaveric studies [12].
• In a cadaver model, detachment of the central slip from the middle phalanx produced a decrease in extension of the PIP joint [15].
• In a cadaver model, when the transverse and oblique fibers of the interosseous hood were also divided, extension at the PIP joint was further decreased [15].
• In a cadaver model, a boutonniere deformity occurred only when the central slip, triangular ligament, and transverse and oblique fibers of the interosseous hood were all damaged [15].

Non-Operative

• Chronic boutonniere deformity should be treated with serial casting for adequate extension followed by 3 months of relative motion flexion (RMF) orthotic use prior to surgical intervention [4].
• Chronic boutonniere deformity responds to relative motion flexion splinting if serial casting places the proximal interphalangeal joint in less than -20° extension and the patient actively uses a relative motion flexion orthosis for 3 months [6].
• The use of relative motion flexion orthoses (RMFO) is effective in increasing active distal interphalangeal joint flexion and improving PIP extension in patients with Burton stage 1 chronic boutonniere deformity [36].
• Improvement in digit range of motion is associated with the initiation of treatment within 6 weeks [21].
• Improvement in digit range of motion is not associated with any particular type or length of conservative treatment [21].
• Conservative treatment for central slip injuries involves immobilization of the proximal interphalangeal joint, distal interphalangeal joint, and metacarpophalangeal joint in full extension for four weeks followed by a Capener spring splint for two further weeks [45].
• In a review of 115 central slip injuries, 24 uncomplicated closed or compound injuries treated conservatively resulted in 17 patients (71%) achieving an outcome of less than a 20° extension deficit at the PIPJ and more than 80% return of PIPJ flexion [45].
• Patients treated within six weeks of injury had better outcomes in conservative management of central slip injuries [45].

Operative

• A simple method of repair is described for the correction of the boutonnière deformity in rheumatoid arthritis [5].
• The Y-shaped tendon graft is a useful procedure for the correction of chronic boutonniere deformity [7].
• The cross-lateral band reconstruction technique using palmaris longus autograft is a treatment option for chronic boutonniere deformity when the lateral bands are deficient or damaged [9].
• The cross-lateral band reconstruction technique using palmaris longus autograft yields satisfactory results in chronic boutonniere deformity [9].

Complications

• The prevalence of finger deformities in patients with established rheumatoid arthritis is approximately 14% for swan-neck deformities [16].
• Swan-neck deformity may be caused by synovitis of the metacarpophalangeal, proximal interphalangeal, or distal interphalangeal joints [16].
• In the later stages of both swan-neck and boutonniere deformities, soft-tissue procedures alone may not result in lasting operative correction [16].

Recovery

• Chronic boutonniere deformity should be treated with serial casting for adequate extension followed by 3 months of relative motion flexion orthotic use prior to surgical intervention [4].
• Chronic boutonniere deformity will respond to relative motion flexion splinting if serial casting can place the proximal interphalangeal joint in less than -20° extension and the patient actively uses the hand in a relative motion flexion orthosis for 3 months, recovering flexion [6].
• The Y-shaped tendon graft provided good or excellent results in 16 of 18 patients for the correction of chronic boutonniere deformity [7].
• The incidence of uncorrectable swan-neck and boutonniere deformities is estimated to be between 8% and 16% during the first 2 years after the onset of systemic disease in rheumatoid arthritis [16].
• The prevalence of finger deformities in patients with established rheumatoid arthritis is approximately 14% for swan-neck deformities and 36% for boutonniere deformities [16].
• Treatment decisions for boutonniere deformity in rheumatoid arthritis are based on the degree of joint deformity, joint motion, passive joint correctability, and the status of the articular surface [20].

Key Evidence

• [L5] Differentiating a true boutonniere deformity from a pseudoboutonniere injury is critical in determining clinical management. [1] (10.1016/j.jhsa.2022.10.019)
• [L5] An understanding of the anatomy, clinical presentation, treatment options, and expected outcomes is crucial for optimal treatment of posttraumatic boutonnière and swan neck deformities. [2] (10.5435/jaaos-d-14-00272)
• [L5] The paper outlines the anatomy, pathoanatomy, and treatment concepts for boutonniere deformity, emphasizing that early treatment of central slip injuries can prevent the deformity. [3] (10.1016/s0749-0712(21)00060-3)
• [L4] Similar results occurred for chronic boutonniere deformity using serial casting for adequate extension followed by 3 months of RMF orthotic use, which should be attempted prior to surgical intervention. [4] (10.1016/j.jht.2023.02.005)
• [L4] The natural history of the boutonnière deformity in rheumatoid arthritis is outlined, and a simple method of repair is described. [5] (10.2106/00004623-196951070-00009)
• [L4] Chronic boutonniere deformity will respond to relative motion flexion splinting if serial casting can place the proximal interphalangeal joint in less than -20° extension, and the patient actively uses the hand in a relative motion flexion orthosis for 3 months, recovering flexion. [6] (10.1097/sap.0000000000002307)
• [L4] The Y-shaped tendon graft can be a useful procedure for the correction of chronic boutonniere deformity; in our patient series, this provided good or excellent results in 16 of 18 patients. [7] (10.1016/j.jhsa.2021.01.003)
• [Case_report] The case extends understanding of congenital boutonniere deformity as various embryonic developmental failures and suggests a reliable surgical option involving central slip reconstruction. [8] (10.1016/j.jhsa.2014.05.030)
• [L4] In chronic boutonniere deformity, when the lateral bands are deficient or damaged, the cross-lateral band reconstruction technique using palmaris longus autograft is a treatment option with satisfactory results. [9] (10.1016/j.jhsa.2017.04.010)
• [L3] The prevalence of boutonnière deformity without rheumatoid arthritis or trauma is approximately 13%. [11] (10.1177/1753193417704610)
• [L5] The study developed and validated a finite element model that successfully replicated the behavior of the digit under specific scenarios, including the extension of the DIP joint during Elson's test observed in cadaveric studies. [12] (10.1186/s13018-025-06329-3)
• [L4] Transection of the terminal extensor tendon is a useful procedure for salvage of the boutonniere deformity. [13] (10.1016/s0749-0712(21)00065-2)
• [L5] [15] (10.1016/j.jhsa.2017.07.011)
• [L5] [16] (10.5435/00124635-199903000-00002)
• [Paper] [19] (10.1016/j.hcl.2012.05.044)
• [L5] Treatment decisions are based on the degree of joint deformity, joint motion, passive joint correctability, and the status of the articular surface. [20] (10.1016/j.jhsa.2011.05.029)
• [L3] Improvement in digit ROM was associated with initiation of treatment within 6 weeks, but not with any particular type or length of conservative treatment. [21] (10.1016/j.jht.2025.02.013)
• [L4] The use of RMFO is effective in increasing active distal interphalangeal joint flexion and improving PIP extension in patients with Burton stage 1 chronic boutonniere deformity. [36] (10.1016/j.jhsa.2022.08.007)
• [Case_report] Hand surgeons should be aware that injury to the extensor mechanism and specifically the central slip can lead to snapping or catching at the PIP joint in the finger. [39] (10.1177/15589447221081876)
• [Paper] Extension of the PIP joint decreases as these structures are progressively damaged. [40] (10.1016/s0363-5023(12)60014-8)
• [L4] [45] (10.1177/1758998318822663)
• [L4] Due to long-standing complex pathophysiological changes, full correction may not be possible, and a few degrees of PIP joint extension deficit is inevitable. [46] (10.1016/j.otsr.2021.102971)
• [L4] The prognosis is far better after irreducible than after reducible volar dislocations because the extensor mechanism is displaced, not disrupted. [47] (10.2106/00004623-197860010-00023)

References

[1] Boutonniere Versus Pseudoboutonniere Deformities: Pathoanatomy, Diagnosis, and Treatment. The Journal of Hand Surgery. 2023. DOI: 10.1016/j.jhsa.2022.10.019

[2] Posttraumatic Boutonnière and Swan Neck Deformities. Journal of the American Academy of Orthopaedic Surgeons. 2015. DOI: 10.5435/jaaos-d-14-00272

[3] BOUTONNIERE DEFORMITY. Hand Clinics. 1995. DOI: 10.1016/s0749-0712(21)00060-3

[4] The relative motion concept in acute and chronic boutonniere deformity: Invited commentary. Journal of Hand Therapy. 2023. DOI: 10.1016/j.jht.2023.02.005

[5] Correction of the Rheumatoid Boutonnière Deformity. The Journal of Bone & Joint Surgery. 1969. DOI: 10.2106/00004623-196951070-00009

[6] A Paradigm Shift in Managing Acute and Chronic Boutonniere Deformity. Annals of Plastic Surgery. 2020. DOI: 10.1097/sap.0000000000002307

[7] Y-Shaped Tendon Graft—A Technique in the Reconstruction of Posttraumatic Chronic Boutonniere Deformity. The Journal of Hand Surgery. 2021. DOI: 10.1016/j.jhsa.2021.01.003

[8] Restoration of the Central Slip in Congenital Form of Boutonniere Deformity: Case Report. The Journal of Hand Surgery. 2014. DOI: 10.1016/j.jhsa.2014.05.030

[9] Chronic Boutonniere Deformity: Cross-Lateral Band Technique Using Palmaris Longus Autograft. The Journal of Hand Surgery. 2017. DOI: 10.1016/j.jhsa.2017.04.010

[10] Extensor Tenotomy for Chronic Boutonniere Deformity of the Finger: REPORT OF TWO CASES.. The Journal of Bone and Joint Surgery. American Volume. 1965.

[11] Thumb boutonnière deformity without rheumatoid arthritis or trauma. Journal of Hand Surgery (European Volume). 2017. DOI: 10.1177/1753193417704610

[12] Assessment of the ligamentous stress distribution in the pathomechanics of the boutonniere deformity through a computational 3D model. Journal of Orthopaedic Surgery and Research. 2025. DOI: 10.1186/s13018-025-06329-3

[13] TREATMENT OF THE CHRONIC BOUTONNIERE DEFORMITY BY EXTENSOR TENOTOMY. Hand Clinics. 1995. DOI: 10.1016/s0749-0712(21)00065-2

[15] Biomechanics of the Acute Boutonniere Deformity. The Journal of Hand Surgery. 2018. DOI: 10.1016/j.jhsa.2017.07.011

[16] Operative Correction of Swan-Neck and Boutonniere Deformities in the Rheumatoid Hand. Journal of the American Academy of Orthopaedic Surgeons. 1999. DOI: 10.5435/00124635-199903000-00002

[18] Anterior dislocation of the proximal interphalangeal joint. A cause of rupture of the central slip of the extensor mechanism.. The Journal of bone and joint surgery. American volume. 1970.

[19] Boutonnière and Pulley Rupture in Elite Athletes. Hand Clinics. 2012. DOI: 10.1016/j.hcl.2012.05.044

[20] Treatment of Boutonniere Finger Deformity in Rheumatoid Arthritis. The Journal of Hand Surgery. 2011. DOI: 10.1016/j.jhsa.2011.05.029

[21] Nonoperative treatment of the Boutonniere deformity: Is there a difference in outcomes?. Journal of Hand Therapy. 2025. DOI: 10.1016/j.jht.2025.02.013

[22] Orthopaedic Knowledge Update 13 Ebook Without Multimedia. Anatomy, Evaluation, Clinical Examination, and Imaging > Evaluation and Clinical Examination: Current Concepts.

[25] Green S Operative Hand Surgery. Interosseous and Hypothenar Muscles.

[36] The Use of Relative Motion Flexion Orthoses for Chronic Boutonniere Deformity. The Journal of Hand Surgery. 2024. DOI: 10.1016/j.jhsa.2022.08.007

[39] Longitudinal Tear of the Central Slip Causing Painful and Unusual Snapping of the Finger: A Case Report. HAND. 2022. DOI: 10.1177/15589447221081876

[40] Biomechanics of the Acute Boutonniere Deformity. The Journal of Hand Surgery. 2012. DOI: 10.1016/s0363-5023(12)60014-8

[45] Therapeutic management of closed central slip injuries: Outcome of a service evaluation. Hand Therapy. 2019. DOI: 10.1177/1758998318822663

[46] RETRACTED: Flexor Digitorum Superficialis tendon transfer for a long-standing boutonniere deformity finger- a retrospective study of 11 cases. Orthopaedics & Traumatology: Surgery & Research. 2021. DOI: 10.1016/j.otsr.2021.102971

[47] Irreducible volar dislocation of the proximal interphalangeal joint of a finger caused by interposition of the intact central slip. The Journal of Bone & Joint Surgery. 1978. DOI: 10.2106/00004623-197860010-00023