Flexion contracture of the proximal interphalangeal (PIP) joint is a common yet complex clinical problem.Movement at this joint is responsible for 85% of the total composite motion of the digit; therefore, a contracture can significantly impair global hand function, in particular when more than one digit is involved.1  Chronic pain, stiffness, and functional deficits can occur, especially in severe cases or when multiple fingers are affected.1,2.Management is  complicated by the complex anatomy of the PIP joint, and the causative structure is difficult to identify. The anatomical structures of the PIP joint to be evaluated and addressed if pathologic include the articular surface, capsule, collateral ligaments, volar plate, extrinsic tendons and sheaths and the skin. Early aggressive supervised therapy does not ensure prevention, and open surgical release is technically challenging, often resulting in disappointing long-term outcomes despite thorough evaluation and careful patient selection.2-6Surgical options for correcting PIP joint contractures encompass arthrolysis, tenolysis, capsulotomy/capsulectomy, local flaps, and skin grafts, with arthrodesis or amputation sometimes necessary for severe cases7,8. Notably, Sprague4 reported a complete loss of the operative gain at the 1-year follow-up.Ghidella et al2 presented their results with a minimum follow up of 24 months in 68 contracted PIP joints treated by serial capsulectomy. The average improvement in active motion was 8°, with a revision rate of 35%. Over the past 20 years, external fixation of contracted PIP joints using ligamentotaxis distraction has gained popularity 9 due to its simplicity, effectiveness, and minimal invasiveness, reducing the risk of complications associated with open surgery and yielding good functional outcomes in various studies.7e16 We have previously reported our short-term results from dynamic external fixation in the management of post-traumatic PIP joint deformity.9,12,13 The average improvement in range of movement was between 42 and 63 compared with the 25 to 30 obtained from surgical releases reported in the literature.9,13e15,17 We present the medium- to long-term results for 20 post-traumatic/post burn PIP joint flexion contractures treated by joint distraction using the Pennig mini external fixator (Orthofix, Surrey, England) and discuss the key learning points from our experience with using this technique.

Aim: Evaluation of utilization of distractors in flexion contracture of interphalangeal joints of hand.

In this study, we evaluated 20 consecutive patients (21 fingers) with posttraumatic/ post burn chronic flexion contractures of the proximal interphalangeal (PIP) joint who did not respond to conservative treatments, such as extensive hand therapy and dynamic extension orthoses. The cohort included 13 males and 7 females, with a mean age of 43 years (range 17 to 69 years).

Surgical intervention was indicated for patients presenting with PIP joint contractures greater than 60 degrees, based on their functional impairment and following informed discussions about treatment options. The average duration from injury to surgery was 48 months (range 6 to 84 months). The types of injuries treated included volar lip fractures with avulsion (4 cases), volar dislocations with dorsal avulsion fractures (4 cases), and joint dislocations without fractures (12 cases), which included four subluxations. Preoperative radiographs confirmed no signs of osteoarthritis or joint incongruity in any patient. Patients with contractures resulting from burns, Dupuytren's disease, congenital anomalies, severe crush injuries, or replantation were excluded, as were those under 18 or over 70 years of age.

Data collection

Data collection focused on the duration of distraction, range of motion of the injured joint before and after treatment, and any postoperative complications. Outcomes were compared between two age groups: patients younger than 40 years and those aged 40 years or older. Ethical approval for the study was not required due to the established nature of the treatment at our institution.

Table 1: Pre and post-operative range of motion

Statistical Significance: P < .001 for active range of movement improvement.

Table 2: Range of motion gained between different age groups

Patients younger than 40 fared slightly better than those 40 years old and older (Table 2), but this difference was not statistically significant (P ¼ .149).

Table 3: Complications and Management in Pin-Based Finger Lengthening

2 joint contractures caused pin bending; asymmetrical joint opening in 1 cases; 1 subluxation cases managed; 0 with temporary DIP deformity; mild inflammation in 2; 0 pin-track infections treated; mild initial pain in 14, all patients satisfied with outcomes.

Schenck18 first highlighted the application of external fixation for addressing chronic flexion deformities of the proximal interphalangeal (PIP) joint, a technique later expanded by Richtr and Rysavý14. Over the last decade, this method has gained traction for its ability to release contractures, even in particularly challenging cases. Various devices have been explored, including the Joshi external stabilizing system, a straightforward uniplanar construct that has effectively treated8,10 contractures related to leprosy and burns. More complex solutions, like multiplanar distractors, have been introduced for contractures post-finger replantation19.

Bain et al. 20contributed a dynamic extension technique utilizing a hinge external fixator, achieving favorable outcomes in initial cases. In our own study from 2002, we reported significant improvements in 27 PIP joints treated with a similar hinge fixator, noting an average reduction in flexion contracture of 38 degrees and an active range of motion increase of 42 degrees13. However, we observed a residual extension lag of about 15 degrees, likely due to inadequate distraction, which led to partial correction of the deformity, particularly on the volar side.

Additionally, we have successfully employed the Pennig mini-external fixator for a range of complex conditions, including neglected dorsal fracture-dislocations and late-presenting intra-articular fractures21-23. We found this device safe and easy to use, with no long-term complications like chronic regional pain syndrome reported. In our early case series, treatment of 10 to 30 PIP joint contractures resulted in flexion gains of 54 to 63 degrees and extension gains of 47 degrees. These improvements were maintained for up to 34 months after surgery, with only one week of fixation needed to adequately mature the lengthened soft tissue12,13.

We believe the effectiveness of the distraction device lies in its ability to lengthen periarticular structures, particularly the volar plate, more effectively than extension devices. This mechanism fosters soft tissue laxity, restores normal anatomy, and corrects deformities. The Pennig apparatus also offers better-controlled and gradual ligamentous distraction, requiring just two pins, which minimizes the risk of soft tissue damage and pin site infections. Overall, our findings support the Pennig device as a valuable tool in the management of PIP joint contractures.

In our study utilizing external fixation, however, we did not observe a significant difference in outcomes related to age. This discrepancy may stem from the nature of the external fixation procedure itself, which is generally less invasive compared to traditional open techniques. The reduced trauma and surgical intervention associated with external fixation might enable a broader age range of patients to experience favorable results. Consequently, this approach may provide a viable treatment option for older patients who might otherwise be deemed unsuitable candidates for more invasive surgical interventions. Our findings suggest that external fixation12 could help bridge the gap in outcomes seen with age in the management of PIP joint contractures.The age of a patient has consistently been recognized as a critical prognostic factor in the outcomes of open contracture releases. For instance, Iselin and Revol24 reported that individuals younger than 27 years achieved a 75% rate of satisfactory results, while those in older age groups only saw a mere 22% success rate. Similarly, Ghidella et al. 2advised against attempting to correct PIP joint contractures in patients over 43 years of age, citing a strong association between advanced age and poorer surgical outcomes.

In our study we found that the improvements in range of motion can be sustained for up to  12 months without the emergence of long-term complications. This suggests that joint distraction may offer a more effective solution for maintaining mobility in the PIP joint compared to traditional methods, providing a promising avenue for future treatment strategies in managing burn contractures.Ravishankar et al.10 conducted a study on the long-term outcomes of external fixation in 94 cases of burn contractures affecting the proximal interphalangeal (PIP) joint. Their findings revealed a gradual loss of motion over an average follow-up period of 54 months, which aligns with similar observations made in patients who underwent open surgical procedures4. This raises concerns about the durability of functional improvements achieved through these interventions.In contrast, Ghidella et al. 2 suggested that the expected range of joint movement remains relatively stable after 24 months, indicating that while initial gains may be observed, they might plateau over time. However, our research indicates a more optimistic outcome for patients undergoing joint distraction techniques

Our study underscores the effectiveness of external fixation, particularly the Pennig mini-external fixator, in managing chronic flexion contractures of the proximal interphalangeal (PIP) joint. This technique not only facilitates significant improvements in range of motion but also maintains these gains for up to 12 months without long-term complications. Unlike traditional open surgical methods, which often show diminished outcomes with increasing age, our findings indicate that age does not significantly affect the success of external fixation. This suggests that external fixation could serve as a viable treatment option for older patients who may be at risk with more invasive procedures. Overall, the evidence supports the use of joint distraction techniques as a promising approach for treating PIP joint contractures, offering hope for better functional outcomes across a wider patient demographic.

1. Bruser P, Poss T, Larkin G. Results of proximal interphalangeal joint release for flexion contractures: midlateral versus palmar incision. J Hand Surg Am. 1999;24(2):288e294. 2. Ghidella SD, Segalman KA, Murphey MS. Long-term results of surgical management of proximal interphalangeal joint contracture. J Hand Surg Am. 2002;27(5):799e805.
2. Benson LS, Bailie DS. Proximal interphalangeal joint injuries of the hand. Part II: treatment and complications. Am J Orthop (Belle Mead NJ). 1996;25(8):527e530.
3. Sprague BL. Proximal interphalangeal joint contractures and their treatment. J Trauma. 1976;16(4):259e265.
4. Foucher G, Lenoble E, Ben-Youssef K, Sammut D. A post-operative regime after digital flexor tenolysis. A series of 72 patients. J Hand Surg Br. 1993;18(1):35e40.
5. Koller VR, Choi MS, Bayer GS, Millesi H. Analysis of change in f inger function after flexor tenolysis [in German]. Handchir Mikrochir Plast Chir. 1996;28(4):204e209.
6. da Silva PN, Barbosa R, Ferreira P, et al. Correction of long term joint contractures of the hand by distraction. A case report. Br J Plast Surg. 2005;58(8):1148e1151.
7. Salafia A, Chauhan G. Joshi External Stabilising System (JESS) in proximal interphalangeal joint (PIP) contractures in leprosy. Indian J Lepr. 1997;69(4):331e339.
8. Houshian S, Schroeder HA. Distraction with external fixator for contractures of proximal interphalangeal joints: good outcome in 10 cases. Acta Orthop Scand. 2004;75(2):225e228.
9. Ravishanker R. Distraction correction for flexion contractures of the f ingers: a minimally invasive technique. Indian J Plastic Surg. 2003;36(2):99e103.
10. Houshian S, Chikkamuniyappa C. Distraction correction of chronic f lexion contractures of PIP joint: comparison between two distraction rates. J Hand Surg Am. 2007;32(5):651e656.
11. Houshian S, Chikkamuniyappa C, Schroeder H. Gradual joint distraction of post-traumatic flexion contracture of the proximal interphalangeal joint by a mini-external fixator. J Bone Joint Surg Br. 2007;89(2):206e209.
12. Houshian S, Gynning B, Schrøder HA. Chronic flexion contracture of proximal interphalangeal joint treated with the compass hinge external fixator. A consecutive series of 27 cases. J Hand Surg Br. 2002;27(4):356e358.
13. Richtr M, Rysavý M. Use of the Volkov-Oganesjan distractionreposition apparatus in treatment of flexion contractures of the interphalangeal joints [in Czech]. Acta Chir Orthop Traumatol Czech. 1991;58(1e2):9e19.
14. Theivendran K, Pollock J, Rajaratnam V. Proximal interphalangeal joint fractures of the hand: treatment with an external dynamic traction device. Ann Plast Surg. 2007;58(6):625e629.
15. Goldberg E, Unglaub F, Kneser U, Horch RE. Intraarticular fractures of the proximal interphalangeal joint: dynamic early functional therapy with an external fixation system [in German]. Unfallchirurg. 2009;112(3):337e345.
16. Hogan CJ, Nunley JA. Posttraumatic proximal interphalangeal joint flexion contractures. J Am Acad Orthop Surg. 2006;14(9): 524e533.
17. Schenck RR. Dynamic traction and early passive movement for fractures of the proximal interphalangeal joint. J Hand Surg Am. 1986;11(6):850e858.
18. Kasabian A, McCarthy J, Karp N. Use of a multiplanar distracter for the correction of a proximal interphalangeal joint contracture. Ann Plast Surg. 1998;40(4):378e381.
19. Bain GI, Janak AM, Heptinstall RJ, Bria M. Dynamic external fixation for injuries of the proximal interphalangeal joint. J Bone Joint Surg Br. 1998;80(6):1014e1019.
20. Houshian S, Ghani A, Chikkamuniyappa C, Sakka SA. Single-stage distraction correction for neglected dorsal fracture dislocations of the proximal interphalangeal joint: a report of eight cases. J Hand Surg Eur Vol. 2008;33(3):345e349.
21. Houshian S, Jing SS. Treatment of Rolando fracture by capsuloligamentotaxis using mini external fixator: a report of sixteen cases. Hand Surg. 2013;18(1):73e78.
22. Houshian S, Jing SS. A new technique for closed management of displaced intra-articular fractures of metacarpal and phalangeal head which were delayed on presentation: report of eight cases. J Hand Surg Eur Vol. 2013 Feb 22 Epub ahead of print.
23. Iselin F, Revol M. Fixed post-traumatic flexion-contractures of digits. Review of thirty-three cases. Ann Chir Main. 1983;2(2): 143e153.