Stability of acute dorsal fracture dislocations of the proximal interphalangeal joint: a biomechanical study

Hemi-hamate arthroplasty outcomes: a single-centre experience

This retrospective observational study evaluated outcomes after hemi-hamate arthroplasty. A palmar cortical step caused by the osteochondral graft was associated with reduced proximal interphalangeal joint range of motion compared to a flush palmar cortex at early follow-up (62° vs. 83°; p = 0.006).

Proximal Interphalangeal Joint Congruity: A Biomechanical Study

BACKGROUND

Surgical approaches to the proximal interphalangeal (PIP) joint often require disruption of soft tissue stabilizers. Additionally, PIP joint injuries frequently result in soft tissue disruption. This study evaluates the necessity of repairing soft tissue stabilizers by assessing their role in maintaining native joint congruity.

METHODS

Eight specimens were used to evaluate congruity at 0° and 30° flexion when loaded with 2 N of valgus force. This was performed in the native joint and after sequential sectioning of the surrounding ligaments in order: volar plate (VP), radial collateral ligament (CL), and ulnar CL. The skin flap was sutured with the ligaments unrepaired and the load was reapplied. Radiographs were taken after each load and used to measure the joint line convergence angle (JLCA).

RESULTS

Mean JLCA increased in both degrees of flexion after ligaments were sectioned but was only significantly different from the native joint after the VP was disrupted along with 1 CL. Joint congruity improved following repair of the skin flap in both degrees of flexion but was not significant. Joints were more congruent in 30° flexion for all subgroups, but none were significantly different compared to 0° flexion.

CONCLUSIONS

Disruption of the VP is insufficient to significantly alter PIP joint congruity. While sectioning of both the VP and CLs resulted in a statistically significant change in joint congruity, mean JLCA demonstrated changes of minor clinical significance. The osseous anatomy of the phalanges imparts inherent stability that maintains a congruent joint despite loss of the soft tissue stabilizers.

A randomised clinical trial comparing outcomes of a single digit volar plate injury - Buddy loops versus dorsal thermoplastic orthosis in a neutral position: study protocol

BACKGROUND

Volar plate injuries are a common hand injury and complications associated with this injury such as a fixed flexion deformity, persistent pain and oedema can have a significant impact on a person's function. The literature reports these injuries are treated using various splinting materials such as thermoplastic, in varying degrees of proximal interphalangeal joint flexion or buddy loops. Despite volar plate injuries being reported as common, optimal non-surgical treatment of these injuries remains unclear. This study aims to investigate whether a dorsal blocking orthosis in a neutral position (0⁰) is more effective than buddy loops for a volar plate injury to the proximal interphalangeal joint in preventing a fixed flexion deformity, reducing pain, managing oedema, and promoting function.

METHODS

This study is a single-centre, prospective parallel-group, single blinded (assessor), randomised clinical trial. Patients between 18-65 years, who have sustained a volar plate injury to a single digit, have adequate cognitive functioning and give written informed consent will be invited to participate in this study. Patients will be randomised to either the control group where they will be fitted with buddy loops and commence early active motion exercises or the experimental group where they will receive a dorsal thermoplastic orthosis in a neutral position and commence early active motion exercises. The primary outcome measure is passive proximal interphalangeal joint extension and secondary outcome measures include passive range of motion, total passive motion, active range of motion, total active motion, grip strength, oedema, pain, function and adherence to treatment. Assessments will be completed until 8 weeks following commencement of treatment. The sample size calculation indicates that 23 patients is required in each group. With an expected dropout rate of 25% a total of 32 patients will be enrolled in each group.

DISCUSSION

This study will assist in trying to improve treatment of volar plate injuries and assist in reducing complications associated with volar plate injuries, potentially reducing the need for prolonged hand therapy.

TRIAL REGISTRATION

This trial has been registered with the Australian New Zealand Clinical Trials Registry (ACTRN12622001425785p). Ethical approval has been granted by the South Eastern Sydney Local Health District ethical committee (2022/ETH01697).

Bridge Plating of a First Proximal Phalanx Intra-articular Base Fracture—Benefits Over External Fixation

A 62-year-old right-handed man presented with an intra-articular fracture of the proximal phalanx base of the right thumb after a motor vehicle accident. Computed tomography revealed severe comminution, apex volar angulation, and minimal bone stock at the proximal phalanx base. The patient consented to open reduction internal fixation with a locking plate to bridge the fracture and cancellous bone grafting of the distal radius. The hardware was removed at 8 weeks, without complications. The patient began therapy, and at 19 weeks following the surgery, the patient's thumb metacarpophalangeal joint motion was 10° to 30° and the interphalangeal motion was 30° to 50°. Radiographs showed fracture union and proper alignment, with modest shortening. The patient was satisfied with this result. Bridge plating may be an alternative to external fixation for certain thumb fractures, with the potential to maintain alignment and articular congruity while permitting earlier return to activities of daily living and avoiding the risk of pin-track infections.

Comparison of 3 Dynamic External Fixation Devices for Proximal Interphalangeal Joint Dorsal Fracture-Dislocations in a Cadaver Model

PURPOSE

Several improvised dynamic external fixation devices are used for treating unstable dorsal proximal interphalangeal (PIP) joint fracture-dislocations. We compared the effectiveness of 3 constructs for simulated dorsal PIP joint fracture-dislocations in a cadaver model.

METHODS

We tested 30 digits from 10 fresh-frozen, thawed cadaver hands. We aimed to remove the palmar 50% of the base of each digit's middle phalanx (P2), simulating an unstable dorsal PIP joint fracture-dislocation. Each PIP joint was then stabilized via external fixation with either a pins-and-rubber-bands construct, pins-only construct, or tuberculin syringe-pins construct. We allocated 10 digits per fixation group. The finger tendons were secured to a computer-controlled stepper motor-driven linear actuator. Via this mechanism, all PIP joints were taken through 1,400 cycles of flexion-extension. With the PIP joint in neutral extension, we measured the P2 dorsal translation at baseline, after fixator stabilization, and after the motion protocol.

RESULTS

The actual mean P2 palmar defect created was 48% of the base. All PIP joints were unstable after creating the defect, with a mean initial P2 dorsal displacement of 3.7 mm. After application of the fixators, all PIP joint dislocations were reduced. The median residual P2 dorsal displacements were 0.0 mm for the pins-rubber bands group, 0.1 mm for the pins-only group, and 0.5 mm for the syringe-pins group. There were no cases of PIP joint redislocation after flexion-extension cycling, and the median dorsal P2 displacements were 0.0 mm for the pins-rubber bands group; 0.0 mm for the pins-only group; and 0.5 mm for the syringe-pins group.

CONCLUSIONS

All 3 external fixators restored PIP joint stability following simulated dorsal fracture-dislocation, with all reductions maintained after motion testing. The syringe-pins construct had significantly greater median residual P2 dorsal displacement after the initial reduction and motion testing, which is of unclear clinical importance.

CLINICAL RELEVANCE

This study informs surgeon decision-making when considering dynamic external fixator options for dorsal PIP joint fracture-dislocations.

Hemihamate arthroplasties in pilon fractures: a modified approach and experience in 30 patients

Hemihamate arthroplasty is an established method of managing difficult Pilon fractures of the proximal interphalangeal (PIP) joint. We present our experience in 30 patients, whose injuries were further complicated by severe comminution and late presentations. Several modifications were utilized, including preoperative distraction, use of smaller size grafts and functional release of collaterals. The average follow-up period was 28 months (range 18 to 28). Postoperatively, the average range of flexion at the PIP joint improved from 30° (range 20° to 45°) preoperatively to 104° (90° to 110°) at the final follow-up. The average extension lag was 6° (0° to 20°). Five patients required secondary procedures and no patient had a recurrent dorsal dislocation. We propose these modifications in the use of hemihamate arthroplasty for the management of difficult PIP joint fractures.Level of evidence: IV.

The Importance of Restoring Anatomy of the Proximal Interphalangeal Joint in Dorsal Fracture Dislocations

The proximal interphalangeal joint (PIPJ) is a complex anatomical structure. In managing fracture dislocations about the PIPJ, the aim is to restore a congruent joint that allows for smooth gliding motion. Detailed knowledge of the anatomy and biomechanics of the PIPJ is necessary in managing these injuries with predictable success. The breadth of techniques previously described in the treatment of such injuries is testament to the difficulties faced in achieving optimal clinical and radiological outcomes. In this article we detail the anatomy and biomechanics of the PIPJ and summarize current literature and principles for the treatment of dorsal fracture dislocations.

Use of a Costal Osteochondral Graft for Reconstruction of a Proximal Phalanx Head with a Comminuted Fracture of the Proximal Interphalangeal Joint

We report the use of costal osteochondral grafting with a pins and rubbers traction system (PRTS) for treatment of a complex cartilage defect of the proximal interphalangeal (PIP) joint in a 41-year-old male carpenter who had inadvertently incompletely severed his finger with a power saw. The skin laceration extended to the dorsal aspect of his ring finger and resulted in incomplete loss of the ulnar condyle and comminution of the radial condyle of the proximal phalanx of the PIP joint. The diagnosis was intra-articular PIP joint open fracture of the left ring finger with a 60% defect of the proximal phalanx joint surface. Three weeks after the injury, PIP joint reconstruction was performed with a costal osteochondral graft harvested at the osteochondral junction of the fifth rib. The volar side of the proximal phalanx cortex and the condyles of the proximal phalanx on each side, which included the origin of the collateral ligaments, were preserved. The graft was shaped to match the defect, and biplane fixation with three miniscrews was subsequently performed. Last, a PRTS was attached. At 6 months postoperatively, the patient returned to his job; at 12 months postoperatively, the joint was stable and free of pain. This technique enabled preservation of joint stabilizers and rigid fixation of the graft, resulting in a good outcome. Our modified costal osteochondral graft with a PRTS is useful for severe intra-articular fractures of the PIP joint and should be considered before salvage procedures.

The Relationship Between Hemihamate Graft Size and Proximal Interphalangeal Joint Flexion for Reconstruction of Fracture-Dislocations: A Biomechanical Study

PURPOSE

The purpose of this study was to determine the relationship between hemihamate graft size and proximal interphalangeal (PIP) joint flexion in a biomechanical fracture-dislocation model.

METHODS

We simulated middle finger PIP fracture-dislocations in 5 cadaver hands by resecting 50% of the palmar articular surface of the middle phalanx (P2) base. Fluoroscopy was used to confirm dorsal subluxation of the middle phalanx base after resection. A 10-mm osteochondral hamate graft was contoured to reconstruct the volar lip of the middle phalanx and was progressively downsized by 2-mm increments for each trial. A computer-controlled articulator and jig simulated active flexion and extension of the fingers. Maximum PIP flexion was measured at each graft size using fluoroscopy and digital imaging software. Clinically significant flexion block was defined as PIP flexion less than 90°.

RESULTS

The actual mean size of the volar defect created was 52% (3.5 mm) of the middle phalanx articular surface, which created instability and dorsal subluxation in all tested fingers. After hemihamate reconstruction, all specimens were stable throughout flexion and extension for all graft sizes. A flexion block of 90° occurred at a mean graft size of 191% of the defect (6.5 mm). With regard to the volar lip of the P2, grafts that projected an average 0.8 mm past the native volar lip position had 98° (range, 84°-107°) maximum PIP flexion. Grafts that projected an average of 3.1 mm past the native volar lip position had 90° (range, 69°-100°) maximum PIP flexion. Linear regression modeling incorporating all of the results predicted flexion block to occur at a graft size as small as 166% of the 50% volar P2 defect. In this model, for every 50% (1.7-mm) increase in graft size relative to the defect, PIP flexion decreased by approximately 6°.

CONCLUSIONS

Nonanatomical hemihamate grafts produce a PIP flexion block at extreme sizes, predicted to occur at greater than 166% of a 50% P2 base articular defect in our model. This suggests that relatively large grafts can be used for reconstruction of PIP fracture-dislocations without substantial biomechanical block to PIP flexion. We suggest sizing no larger than 3 mm past the native P2 volar lip position to avoid an important mechanical block to PIP flexion.

CLINICAL RELEVANCE

The information from this study helps surgeons understand how large a hemihamate graft can be used for P2 volar base reconstruction before having a negative impact on PIP flexion.

Injuries Around the Proximal Interphalangeal Joint

Proximal interphalangeal joint (PIPJ) injuries are common and challenging to treat, involving a spectrum of conditions ranging from isolated ligamentous injuries to severe fracture dislocations. The main goal of treatment is to achieve a congruent, stable joint, which is key to achieving early range of motion and a favorable outcome. Injuries that do not compromise the stability of the joint may be treated nonsurgically, whereas those that render the joint unstable may be managed with one of many surgical strategies available. This article focuses on the current practices of treatment of injuries around the PIPJ.

Unstable Dorsal Fracture-Dislocations of the Proximal Interphalangeal Joint: Volar Plate Fixation with or without Bone Graft

BACKGROUND

To evaluate the treatment of severe dorsal fracture dislocation (DFD) injuries of the proximal interphalangeal joint (PIPJ) by open reduction, bone grafting and fixation with mini-hook plates.

METHODS

Fourteen patients with extensive dorsal fracture dislocation of the PIPJ were operatively treated to reconstruct the fractured middle phalanx volar lip using a fabricated hook plate in conjunction with elevation and bone grafting of depressed articular fragments where present.

RESULTS

Restoration of PIPJ articular anatomy and congruence by hook plate fixation permitted full-range mobilization of the joint during fracture healing, with an average arc of motion of 81° and an average loss of extension of 12.9° at a minimum of 6 months follow up. Hook plate treatment of PIPJ fracture dislocation restores articular anatomy and joint congruence at a single sitting and permits post-operative mobilization without the need for extension block splinting.

CONCLUSIONS

Our results demonstrate a good range of motion following treatment, however hardware removal and tenolysis was necessary in 36% of cases.

Joint distraction and early mobilization using a new dynamic external finger fixator for the treatment of fracture-dislocations of the proximal interphalangeal joint

BACKGROUND

Dynamic external fixation is a useful treatment option for unstable fracture-dislocations of the proximal interphalangeal (PIP) joint, because it simultaneously reduces axial pressure load on the joint surface, maintains congruent joint reduction, and permits early joint motion. However, most current devices are large, hindering finger movement, and unstable. To address these problems, we developed a dynamic external finger fixator, named the Micro Ortho Fixator^®. The purpose of this study was to review the results of using the new external finger fixator to treat unstable fracture-dislocations of the PIP joint.

MATERIALS AND METHODS

Nine patients who sustained unstable fracture-dislocation injuries of the PIP joint were treated with the Micro Ortho Fixator^®. Seven fractures were accompanied by depressed bony fragments at the base of the middle phalanx. All patients were evaluated for pain and range of PIP motion at the final follow-up. Radiographs of the affected fingers were evaluated for PIP congruity and reduction. The mean follow-up duration was 11.1 months (range: 6-33 months).

RESULTS

At the final follow-up, pain averaged 0.3 (range: 0-2) on the Numeric Pain Rating Scale, and the total arc of motion at the PIP joint averaged 91.2° (range: 50-110°). All fractures had healed, and the intra-articular step-off improved from 1.9 mm (SD: 1.0) before surgery to 0.2 mm (SD: 0.4) at the final follow-up. The patients who sustained sports injuries returned to competition after an average of 3.5 months (range: 2.5-4 months).

CONCLUSION

The external fixator is compact and facilitates range-of-motion (ROM) exercises, has high stability, and achieves good joint congruity and an ROM equivalent to the healthy joint of the patient.

STUDY DESIGN/LEVEL OF EVIDENCE

Therapeutic/IV.

Hand Fractures: Indications, the Tried and True and New Innovations

Hand fractures are the second most common fracture of the upper extremity, and management of patients with these injuries is common for most hand surgery practices. In this article, we outline the principles of management of these injuries with a special focus on those that are common or complex. We also highlight recent innovations in the context of these injuries. From this cross-section of contemporary evidence on phalangeal and metacarpal fracture treatment, we have noted a trend toward minimally invasive surgery with immediate postoperative mobilization, the use of wide-awake anesthesia, as well as sustained investigation and innovation in the biomechanics and treatment of proximal interphalangeal joint fracture dislocations.

In vitro kinematics of the proximal interphalangeal joint in the finger after progressive disruption of the main supporting structures

BACKGROUND

Fractures and dislocations of the proximal interphalangeal (PIP) joint of the fingers are among the most common causes of injury in the hand. Objective assessment of the kinematic alterations occurring when the supporting structures are disrupted is critical to obtain a more accurate indication of joint stability.

METHODS

An in vitro cadaver model of the hand was used to evaluate the kinematics of the PIP joint in the finger during active unrestrained flexion and extension. The kinematics of the PIP joint following progressive disruption of the main supporting structures was measured using an optical tracking system and compared with those in the intact joint.

RESULTS

Flexion of the intact PIP joint was associated with joint compression, volar displacement, and rotational movements. Release of the main soft-tissue stabilizers and 30 % of volar lip disruption resulted in substantial alteration of several kinematic variables. The normalized maximum dorsal/volar translation was 0.1 ± 1.3 % in the intact group and 14.4 ± 11.3 % in the injured joint.

CONCLUSIONS

In the intact PIP joint, rotations and translation are strongly coupled to the amount of joint flexion. Gross instability of the PIP joint occurs when disruption of the collateral ligaments and volar plate is accompanied by resection of at least 30 % of volar lip of the middle phalanx. Collateral ligament injuries, volar plate injuries alone, and fractures at the volar base of the middle phalanx that involve less than 30 % of the articular surface are unlikely to result in gross instability and may be managed effectively with non-operative treatments.

Dorsal fracture-dislocations of the proximal interphalangeal joint: evaluation of closed reduction and percutaneous Kirschner wire pinning

BACKGROUND

The purpose of this study is to evaluate the outcome of closed reduction and percutaneous Kirschner wire pinning in acute dorsal fracture-dislocations of the proximal interphalangeal (PIP) joint.

METHODS

Eight men and one woman were treated with closed reduction and percutaneous Kirschner wire pinning by one orthopaedic surgeon. The ring finger was injured in six patients, the small finger in two patients and the middle finger in one patient. The mean joint surface involvement was 36 % (range, 26-49 %). The Kirschner wires were removed after an average of 28 days (range, 24-37 days).

RESULTS

All patients demonstrated a painless, but fusiform, swollen PIP joint after a mean follow-up of 6.5 months. The average flexion of the PIP joint was 106° (range, 80-110), and the average extension of the PIP joint was 4° short of full extension (range, 10 hyperextension-15 flexion contracture). All patients had a concentrically reduced PIP joint with a healed fracture on radiographs. Two patients had radiographic evidence of degenerative changes, but were asymptomatic. One patient developed a superficial pin track infection, which quickly resolved with a short course of antibiotics, and avascular necrosis affecting one of the condyles of the proximal phalanx.

CONCLUSIONS

In agreement with previous studies, closed reduction and percutaneous Kirschner wire pinning in dorsal fracture-dislocations of the PIP joint is a minimally invasive and simple technique which appears to give satisfactory outcomes in the short to intermediate term.

Biomechanical characteristics of hemi-hamate reconstruction versus volar plate arthroplasty in the treatment of dorsal fracture dislocations of the proximal interphalangeal joint

PURPOSE

To compare stability and range of motion after hemi-hamate reconstruction versus volar plate arthroplasty in a biomechanical proximal interphalangeal (PIP) joint fracture-dislocation model.

METHODS

Eighteen digits from 6 cadaver hands were tested. We created defects of 40%, 60%, and 80% in the palmar base of each digit's middle phalanx, simulating an acute PIP joint fracture-dislocation. Each defect scenario was reconstructed with a hemi-hamate arthroplasty followed by a volar plate arthroplasty. A computer-controlled mechanism was used to bring each digit's PIP joint from full extension to full flexion via the digital tendons in each testing state, and in the intact state. During each testing scenario we collected PIP joint cinedata in a true lateral projection using mini-fluoroscopy. A digital radiography program was used to measure the amount of middle phalanx dorsal translation (subluxation) in full PIP joint extension. We recorded the angle at which subluxation, if present, occurred during each testing scenario.

RESULTS

Average dorsal displacement of the middle phalanx in relation to the proximal phalanx was 0.01 mm for the hemi-hamate reconstructed joints and -0.03 mm for the volar plate arthroplasty, compared with the intact state. Flexion contractures were noted in each of the specimens reconstructed with volar plate arthroplasty. Degree of contracture was directly correlated with defect size, averaging 20° for 40% defects, 35° for 60% defects, and 60° for 80% defects. We observed no flexion contractures in the hemi-hamate reconstructions.

CONCLUSIONS

Surgeons can use both hemi-hamate and volar plate arthroplasty to restore PIP joint stability following a fracture dislocation with a large middle phalanx palmar base defect. Use of volar plate arthroplasty led to an increasing flexion contracture as the middle phalanx palmar base defect increased.

CLINICAL RELEVANCE

Clinicians can use the information from this study to help with surgical decision-making and patient education.

Current concepts in treatment of fracture-dislocations of the proximal interphalangeal joint

BACKGROUND

Proximal interphalangeal joint fracture-dislocations are common injuries that require expedient and attentive treatment for the best outcomes. Management can range from protective splinting and early mobilization to complex surgery. In this review, the current concepts surrounding the management of these injuries are reviewed.

METHODS

A literature review was performed of all recent articles pertaining to proximal interphalangeal joint fracture-dislocation, with specific focus on middle phalangeal base fractures. Where appropriate, older articles or articles on closely related injury types were included for completeness. The methodology and outcomes of each study were analyzed.

RESULTS

When small avulsion fractures are present, good results are routinely obtained with reduction and early mobilization of stable injuries. Strategies for management of the unstable dorsal fracture-dislocation have evolved over time. To provide early stability, a variety of techniques have evolved, including closed, percutaneous, external, and internal fixation methods. Although each of these techniques can be successful in skilled hands, none has been subjected to rigorous, prospective, comparative trials. Volar dislocations fare less well, with significant loss of motion in many studies. Pilon fractures represent the most complicated injuries, and return of normal motion is not expected.

CONCLUSIONS

The best outcomes can be achieved by (1) establishing enough stability to allow early motion, (2) restoring gliding joint motion rather than noncongruent motion, and (3) restoring the articular surface congruity when possible. Although the majority of literature on this topic consists of expert opinion and retrospective case series, the consensus appears to favor less invasive techniques whenever possible.