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

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.

Non-vascularized partial joint transfer for Finger Proximal Interphalangeal joint reconstruction: a series of 9 patients

INTRODUCTION

Finger proximal interphalangeal joint (PIP) reconstruction after the destruction of parts of the joint remains challenging. Surgical techniques include implant arthroplasty, arthrodesis, free vascularized joint transfer, and non-vascularized bone and joint transfer. This study analyzes our experience after non-vascularized transfer in terms of range of motion, postoperative rehabilitation, and patient satisfaction.

MATERIALS AND METHODS

Between 2009 and 2014, ten patients underwent non-vascularized partial joint transfer for PIP joint reconstruction. One of them was lost to follow-up. Included patients had osteochondral partial joint transplants of 25-50% of the toes (n = 4) and the hand (n = 5). Range of motion (ROM), grip-, and pinch-strength were measured at the last follow-up control and compared to the healthy side. Patients were asked to score the pain at rest/ on load on a visual scale (VAS: 0 = no pain; 10 = excruciating pain). Satisfaction self-assessment was evaluated by asking the patients to grade their postoperative result as excellent, very good, good or poor.

RESULTS

Mean follow-up period was 4.0 years (range 1.2-7.9 years). Mean PIP joint flexion was 93 ± 26° at the last follow-up control. Mean grip- and pinch-strength of the operated side at the last control were, respectively, 43 ± 18 kg and 8 ± 5 kg, close to the healthy side values (45 ± 15 kg and 9 ± 4 kg). Mean pain at rest/on load measured on a visual scale was, respectively, 0.3 ± 1 and 1.8 ± 2. Eight patients (89%) rated their operation as excellent, and one as poor.

CONCLUSION

In this study, non-vascularized partial joint transfer provides a mobile and stable PIP joint 4 years after reconstruction. The surgical technique presented herein is complex depending on additional injuries but results in great patient satisfaction.

Accuracy and Reliability of Radiographic Estimation of Volar Lip Fragment Size in PIP Dorsal Fracture-Dislocations

Background: A cadaveric study was performed to evaluate the accuracy and reliability of radiographic estimation of the volar lip fragment size in proximal interphalangeal joint fracture-dislocations. Methods: Middle phalangeal base volar lip fractures of varying size and morphology were simulated in 18 digits. Radiographs and digital photographs of the middle phalangeal joint surface were obtained pre- and postinjury. Ten orthopedic surgeons of varying levels of training estimated the fracture size based on radiographs. The estimated joint involvement on radiograph was compared with the digitally measured joint involvement. Results: Radiographic estimation underestimated the volar lip fragment size by 9.02%. Estimations possessed high intraobserver (0.76-0.98) and interobserver (0.88-0.97) reliabilities. No differences were detected between levels of surgeon training. Conclusions: The significant underestimation of the volar lip fragment size demonstrates the lack of radiographic estimation accuracy and suggests that surgeons should be mindful of these results when making treatment plans.

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.

[Percutaneous treatment of unstable fractures of the base of the middle phalanx : Technique according to Hintringer and Ender]

OBJECTIVE

Reconstruction of intra-articular impression fractures of the middle phalanx by percutaneous reduction over a small dorsal cortical window. Stabilization by lattice-like arranged K‑wires.

INDICATIONS

Impression fractures of the base of the middle phalanx with or without dislocation in the proximal interphalangeal joint.

CONTRAINDICATIONS

Fractures extending to the shaft of the middle phalanx.

SURGICAL TECHNIQUE

By a cortical window at the dorsum of the middle phalanx (through the tendon free triangle) the impression fracture is reduced from the medullary cavity. Reduction is secured and the articular surface is supported by lattice-like arranged K‑wires.

POSTOPERATIVE MANAGEMENT

Thermoplastic splint for the finger for 6 weeks, subsequently K‑wire removal, active range of motion exercises and hand occupational therapy.

RESULTS

In two case series already published, good clinical and radiological results were reported. No complications were detected in either series.

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.

Treatment of unstable proximal interphalangeal joint fractures with hemi-hamate osteochondral autografts

The primary aim of this study was to assess the clinical and radiological results after hemi-hamate resurfacing arthroplasty in patients with acute or chronic unstable fractures of the base of the middle phalanx and to describe technical features that can facilitate the surgical procedure. Hemi-hamate arthroplasties were done in 19 patients (mean age 39 years) with an isolated fracture at the base of the middle phalanx that involved more than 40% of the articular surface. We assessed ten chronic cases (treated >6 weeks after fracture) and nine acute ones (<6 weeks) at a mean of 24 months. Pain scores, QuickDASH scores, grip strengths, range of motion and radiological findings were recorded at follow-up. At follow-up, the mean active flexion at the proximal interphalangeal joint was to 83° with a mean fixed flexion of 17° (active range of motion 66°). The mean active distal interphalangeal motion was 41°. The mean visual analogue scale score was 1.1. The mean QuickDASH score was 11. The mean pinch strength was 82% of the opposite side. Radiographs revealed one partial graft lysis.

LEVEL OF EVIDENCE

IV.

Extension Block Pinning for Unstable Proximal Interphalangeal Joint Dorsal Fracture Dislocations

PURPOSE

To evaluate the outcomes of extension block pinning used to treat unstable dorsal fracture dislocations of the proximal interphalangeal (PIP) joint. The factors affecting the functional outcome were analyzed.

METHODS

A series of 53 patients with 55 dorsal fracture dislocations of the PIP joint treated with closed reduction and extension block pinning were retrospectively reviewed. Additional percutaneous intramedullary fracture reduction (16 cases) or open fracture reduction (4 cases) had been performed. The radiological and clinical evaluations were included.

RESULTS

At a mean follow-up of 5.2 years (range, 1.0-10.6 years), 39 patients with 41 injured fingers were evaluated. The fracture fragments involved 30% to 69% (mean, 50%) of the articular surface of the middle phalanx. The mean range of motion was 80° (range, 35° to 115°) at the PIP joint with a mean extension loss of 6° (range, 0° to 50°) excluding 2 joints that were salvaged with arthrodesis. The mean range of motion of the distal interphalangeal joint was 68° (range, 5° to 90°). The mean visual analog scale for digit pain was 1.5/10. The reduction of the joint was achieved intraoperatively in all cases. However, after the hardware removal, recurrent minimal subluxation was observed in 12 cases (29%). Recurrent subluxation was associated with increased residual pain. The length of follow-up time had a positive correlation, whereas the patient age had a negative correlation with the range of motion of the injured PIP joint.

CONCLUSIONS

The extension block pinning technique is a simple and valuable technique for treating unstable dorsal PIP fracture-dislocation injuries producing satisfactory long-term results.