The proximal interphalangeal (PIP) joint is essential to finger function mechanics as it significantly improves the range of motion and dexterity required for efficient hand movements. The intricate interaction of soft tissues and bone elements makes up the proximal interphalangeal (PIP) joint. Its stability is mostly due to the tongue-in-groove articulation created by the bicondylar head of the proximal phalanx and the intercondylar prominence at the base of the middle phalanx, which together offer resistance to translational and twisting stresses. The PIP joint permits some lateral mobility and axial rotation during flexion, allowing the finger to rotate slightly toward the scaphoid tubercle, while being conventionally categorized as a uniaxial hinge joint. Approximately 85% of the motion required for a functional grip is thought to be contributed by the PIP joint[1]. The PIP joint is particularly vulnerable to damage because, although it is a hinge joint, it has a limited tolerance for angular, axial, and rotational stress[2]. The PIP joint's long moment arm and exposed location on the finger make it vulnerable. PIP joint injuries are among the most prevalent possible hand injuries in the general population[3]. Significant morbidity, such as chronic stiffness, discomfort, and decreased functional capacity, is frequently caused by injuries and can significantly lower a patient's quality of life[4]. PIP joint injuries, which can range from simple sprains to complicated fractures, can be difficult to diagnose and are frequently disregarded, which can cause treatment delays and perhaps irreversible abnormalities[5].

Both therapists and surgeons continue to find it difficult to categorize proximal interphalangeal joint injuries as they can range in severity from simple sprains to complicated intra-articular fractures. In many cases, delayed or inappropriate treatment results from patients, coaches, and athletic trainers underestimating or ignoring these ailments. Delays in appropriate treatment and rehabilitation can lead to permanent deformities of the affected digit. For instance, prolonged immobilization of the PIP joint may result in joint stiffness and can subsequently cause an irreversible loss of motion. Given the PIP joint’s tendency toward stiffness, pain, arthritis, and residual deformities due to soft tissue imbalance or adhesions, timely and accurate diagnosis followed by appropriate treatment is essential. Many complications are more easily prevented than treated; therefore, proactive measures aimed at preventing further damage and dysfunction following PIP joint injuries are crucial for optimal outcomes. Because of joint stiffness, traditional therapies including internal fixation and immobilization frequently have unsatisfactory results. Treatment strategies that fix fractures and allow for early mobilization to maintain joint function are of vital importance. A number of methods have been put forth to treat PIP joint fracture-dislocations. In 1986, Schenck proposed dynamic traction splinting and early passive movements as effective treatment options for comminuted intra-articular fractures of the PIP joint. Dynamic traction splinting utilizes the principle of ligamentotaxis, wherein gradual extension and distraction of the PIP joint are applied to counteract the deforming forces and promote proper alignment and healing. When employing a distraction technique, caution is required if the flexion contracture exceeds 80° or if the joint is hypermobile, as there is an increased risk of asymmetrical joint opening or subluxation following treatment. To mitigate this risk, serial radiographs and close follow-up evaluations are essential to monitor for any signs of further joint subluxation and ensure proper healing.

A possible solution that successfully enables early joint motion is the modified Suzuki frame developed by Suzuki et al. using Kirschner wires (K-wires) and rubber bands [2][6]. The primary goal of treatment is to restore a painless joint with a functional range of motion that enables effective hand use in daily activities. For PIP joint fracture-dislocations, the modified Suzuki frame provides a number of benefits, resolving problems including joint stiffness and incongruity that are typical of conventional techniques. In contrast to these methods, it permits early mobilization, which lessens stiffness and maintains long-term joint function. The previous design depended entirely on K-wires, and the sliding of K-wires through the bone track resulted in unbalanced traction. This is addressed by the redesigned Suzuki frame. The traction system has been modified by incorporating pieces of rubber bands on each side of the K-wire passing through the proximal phalanx's head, with the wire bent at a specific distance. This modification enhances both the safety and efficacy of the Suzuki frame[7]. This modified model minimizes movement at the pin-bone and pin-skin interfaces, potentially decreasing pin tract complications. Additionally, it reduces the operating time and also traction adjustments are simpler during the postoperative phase[8].

Its simple design makes the frame cost-effective, easily reproducible, avoids the need for expensive implants and minimally interferes with daily activities, making it a practical and effective solution for PIP joint fracture-dislocations[9][10].

The studies on effectiveness of the modified Suzuki frame, including joint stability and patient pain management, are limited. Furthermore, long-term functional outcomes, including comfort, quality of life, and satisfaction, remain underexplored. The aim of this study was to evaluate the functional outcomes of the modified Suzuki frame in patients with fractures involving the PIP joint of the hand. We assessed the immediate post-operative range of motion and grip strength in patients prospectively, as well as evaluated its efficiency, ease of use, and impact on daily activities.

This prospective observational study was conducted at the Orthopaedics Department of Sree Balaji Medical College and Hospital, Chromepet, Chennai, Tamil Nadu, and it included 30 patients attending the OPD with PIP joint fractures from July 2006 to July 2007. Inclusion Criteria The study included patients over 18 years of age with X-ray-confirmed PIP joint fractures who provided consent for surgery. Exclusion Criteria Patients with local skin infections, un-displaced fractures, and compound fractures were excluded. For those identified with fractures involving the PIP joint, a pre-anesthetic checkup was conducted to assess suitability for anesthesia. Treatment measures, including analgesics for pain management and prophylactic antibiotics to prevent infection, were administered. We used closed K-wire insertion. Measures were taken to prevent the pin site infection. Surgical Procedure: All procedures were performed under a ring block. C-arm guiding was used to designate the proximal and middle phalanx heads' centers of rotation. As an axial traction pin, a 1.2 mm K-wire was inserted parallel to the joint line, bent distally on both sides, and extended about 3 cm beyond the fingertip. It was then formed into upward-facing hooks. A second, similar wire was placed through the middle phalanx, parallel to the joint line, with its ends shaped into downward-facing hooks. Rubber bands were attached to both hooks with sufficient tension to distend the joint space by at least 1 mm. In order to realign the fragment in cases of complicated fractures or PIP joint dislocations, a third "reduction pin" was implanted at the base of the misplaced middle phalanx. Postoperative Care: The patient was advised to perform regular active finger range-of-motion exercises. Two doses of post-operative antibiotics were administered, and measures were taken to prevent pin site infections. A finger brace was used during sleep to safeguard the construct. Follow- Up and outcome studied At one-week, one-month, and two-month intervals, patients were followed-up. Total Active Motion (TAM) score, hand grip strength, and postoperative complications, including stiffness, malunion, tendon rupture, chronic pain, and infection, which are during postoperative follow-up, were assessed clinically. Radiological assessment done with appropriate X rays. Overall surgical outcome was categorized as excellent (ideal recovery), good (good recovery with a notable functional improvement), fair (could suggest some progress but persistent functional limits or poor (little progress). TAM Scoring: Functional outcomes of modified Suzuki frame was assessed by TAM score as per “American Society for Surgery of the Hand” proposal. A goniometer was used to measure the active motion arc in degrees for the distal interphalangeal (DIP), PIP, and metacarpophalangeal (MCP) joints separately. The active flexion degrees were added, and any extension deficit was subtracted. The percentage of TAM was then determined by comparing this score to the corresponding uninjured finger on the other hand. Results were categorized as excellent (200-250), good (150-200), fair (100-150),poor (<100) Hand grip strength: Evaluated using a dynamometer in accordance with guidelines recommended by the “American College of Sports Medicine (ACSM)”. Normative values are based on specific age groups to determine if the grip strength is excellent, very good, good, fair, or poor.

The study included 30 patients who had PIP joint fractures in total. Table 1 displays the baseline characteristics of the study population. Majority of patients were middle-age with mean age of 39.6 years ± 13 with male predominance (80%). Injury by objects (36.7%) were  more common and followed by self-falls(33.4%) and 30% by road traffic.  86.7% of the injuries were to the right (dominant) hand and only 13.3% of the injuries were to the left (non-dominant) hand. Among type of fractures, class 1 fractures were more prevalent (50%). Pre and post op Xray images are given in figure1.

Table 1: Baseline characteristics of the study participants

Pre and post degree of flexion of PIP joint is depicted in Figure 2, which showed improved after surgery. Additionally, on assessing degree of flexion at each follow-up the significant improvement was found from immediate post-surgery period to 2 months follow-up as shown in Table 2(p=0.01)

Table 2: Degree of flexion at each post-op follow-up

Figure 1: X-ray images of Case 1: A. Pre-Op and B. Post-Op; Case 2: C. Pre-Op and D. Post-Op

Figure 2: Degree of flexion pre and postoperatively

On comparing the TAM scores at 1 and 2 months postoperatively as shown in Figure 3, a significant improvement (p=0.001) was observed with mean TAM score of 172 ± 31 and 195 ± 29 at 1 and 2 months respectively. The excellent score (200-250) was increased from 23.3% at first month to 66.6% at 2 months (Table 3)

Table 3: TAM score at follow-up

Figure 3: Comparison of TAM at 1 and 2 months postoperatively

The mean hand grip strength was 38.6 ± 6.21 kg (figure 4). Among patients with an excellent surgical outcome, it was reported significantly higher (45.9 ± 1.41 kg).

Figure 4: Distribution of grip strength measurements

Analysis of the surgical outcomes revealed that the majority of cases (66.7%) achieved good results. This was followed by 16.7% of patients who experienced fair recovery, characterized by persistent functional limitations. Only 13.3% reported ideal recovery, with partial or complete restoration of joint function (Table 4).

Table 4: Outcome of surgery

As shown in Table 5, patient satisfaction was evaluated, with the majority (71.0%) rating their experience as good. Additionally, 19.4% of patients reported fair satisfaction, highlighting potential areas for improving patient care.

Table 5: Patient Satisfaction

Further we have analysed the correlation of functional outcomes and other clinical factors with subgroups of overall surgical outcome( Table 6), and found that only degree of flexion and time interval taken for surgery had significant associated (p=0.03 and 0.02, respectively). As age increased the surgical outcome was reported poor, but did not exhibit statistical significance(p=0.58). Good results were predominant in those who had class 1 type of fracture.

Table 6: Association of functional outcome variables with overall surgical outcome

Complex PIP joint fracture-dislocations present a significant treatment challenge and may lead to persistent symptoms such as pain, stiffness, and reduced functionality over time. Although the literature suggests various treatment modalities for these injuries, open reduction and internal fixation (ORIF) or distraction-mobilization appear to be the most valuable options. Both methods facilitate early joint mobilization, which is crucial for promoting recovery and preventing long-term stiffness and dysfunction. Modified Suzuki frame has shown satisfactory result in treating PIP injuries, however, its supporting evidences are limited. We explored the functional outcomes of modified Suzuki frame in PIP injuries.

In the present study, the majority of participants were men, aligning with findings from previous studies[11,12]. Injuries by objects and self-falls were higher among our study cohort, whereas in a longitudinal study by Biplab et al [11] road traffic accidents were more common (40%) and various sports injuries were also reported as common in most of the literature [11]. Consistent with previous findings, the dominant hand was involved in the majority of patients, which is expected due to the preference for using the dominant hand in daily activities[13].

The modified Suzuki frame treatment aims to restore a pain-free joint with a functional range of motion. In the present study, upon analyzing postoperative functional outcome, the degree of flexion, TAM score and grip strength were found to be improved significantly. The degree of flexion was observed to improve from pre-operative degree of flexion of 70 to mean post-operative flexion of 91.6 degrees. However, previous studies have reported inconsistent results in reporting degree of flexion [14]. For instance, a recent study with a minimum follow-up period of two years reported a mean flexion of 82.72 ± 10.5 degrees at the final follow-up[15]. Similarly, a case series by De Soras et al. documented a mean flexion of 84 degrees[14], while another cross-sectional study reported 85.9 degrees[16]. In contrast, Manjumdar et al. observed a mean flexion of 74 degrees, which is comparatively lower than the findings in earlier literature[17]. The proportion of our study participants who had excellent TAM scores significantly increased from 23.3% in the first month(TAM score 172 ± 31) to 66.6% at the two-month follow-up, with a mean TAM score of 195 ± 29. Similarly, a previous follow-up study reported excellent outcomes in 73.95% of cases, with only a small proportion (8.6%) showing poor results[11]. Similarly, a six-month follow-up study reported a significant improvement in TAM scores, with a median of 191.5 (IQR 152–245), and predominantly good outcomes[18]. Another a short-term follow-up study of 18 patients revealed that, based on objective evaluations, they regained 66% of the contralateral TAM and achieved normal grip strength (93%). Moreover, Fractures of the PIP joint in the middle phalanx treated with the PRTS technique showed reliable union in all cases and were generally well tolerated by patients. While the volar lip fractures demonstrated the most favorable outcomes in terms of function and self-reported scores, reduced mobility, infection (41%), and posttraumatic osteoarthritis (61%) remained notable concerns[19].

Additionally, we have evaluated the report from patients on their daily activities which aligns with several studies that suggest restoring joint function is not the only factor in predicting the final outcome of hand fractures[19]. We found that the majority of participant’s reports were good, while only 19.4% reported fair satisfaction. In a recent study, the daily activities score has been reported low after surgery[19], which can be attributed to the statement by Ellis and Tsai, which highlights that most daily activities require no more than 50% of maximal joint motion[20]. Overall, our cohort demonstrated predominantly excellent clinical and functional outcomes. Corroborating these findings, Nanno et al. evaluated the efficacy of the modified Suzuki frame and reported good outcomes in patients with unstable intra-articular fractures of the PIP joint, and satisfactory results were achieved in cases of incomplete amputation of the PIP joint[6]. Further, another retrospective study involving 33 patients from 1994 to 2013 achieved satisfactory clinical results in comminuted intra-articular fractures of PIP joints. Despite initial PIP joint contractures averaging 29° (range, 15°–50°) in 7 patients, these resolved with an intensive therapy program over an average of 36 days (range, 20–60 days). At the completion of treatment, the average active motion of the PIP joints was 92°, with a range of extension/flexion from 0°–10° to 85°–100°. These results highlight the potential for substantial recovery of PIP joint mobility with timely and targeted rehabilitation[21].

Additionally, previous literature has demonstrated that this technique is well-tolerated by patients and can be applied even in cases of open injuries. The device is easy to use and utilizes readily available materials, making it convenient for surgeons[22]. However, some studies have reported that the device can get caught on clothing and may restrict the movement of adjacent fingers[14,17]

Pins and rubber band traction offers several advantages. It is a straightforward technique that typically involves the use of 2 or 3 Kirschner wires and rubber bands. The small diameter of the wires minimizes interference with radiological imaging. This system also permits early active motion of the injured joint. Suzuki et al. noted that, despite the limited active motion allowed, the results could still be considered satisfactory. Even minimal range of motion  can stimulate joint surface nutrition and remodeling, helping to prevent intra-articular adhesions and capsuloligamentous contracture[8].

Several  studies have highlighted the importance of thorough clinical evaluation by the surgeon in accurately guiding both diagnosis and individualized treatment planning. Surgeons should focus their evaluation on identifying the underlying cause of stiffness and determining the specific anatomical structures involved. A comprehensive assessment should include details of the injury mechanism, severity, duration since injury, previous treatments and rehabilitation efforts, overall hand function, and the patient’s occupational demands. Injuries of greater severity are more likely to result in extensive scarring and soft tissue adhesions, complicating recovery and functional outcomes. A thorough history-taking is essential for guiding the surgeon in determining an accurate prognosis and selecting the most appropriate intervention technique. Given that patient compliance is a critical factor in the successful treatment of PIP joint stiffness, it must be addressed during the evaluation phase. Patients should be fully educated on the treatment protocol and have a clear understanding of the treatment plan to ensure optimal healing and recovery[15].

The small sample size and relatively short follow-up period were limitations of our study. In order to explore the efficacy of modified Suzuki frame,more studies with larger sample size and longer follow-up period are required.

The modified Suzuki frame proved to be an effective treatment modality, demonstrating promising results in functional outcomes such as the degree of flexion, hand grip strength, and TAM score. The primary goal of treatment is to restore a painless joint with a functional range of motion that enables effective hand use in daily activities. Early mobilization of the PIP joints was found to promote effective joint remodeling and improved bone function, resulting in a disability-free hand. Further long-term follow-up studies are needed to validate these efficacy and durability of functional outcome. The modified Suzuki frame shows great potential as a valuable technique for future applications, particularly in the management of complex PIP joint injuries. It can be effectively utilized as a standalone treatment, offering enhanced flexibility in addressing challenging fracture-dislocations. One of its most notable advantages is its practicality and efficiency in emergency situations, where it allows for rapid and effective stabilization, making it a reliable choice in acute trauma care.

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