Abstract
Metacarpophalangeal (MCP) joint arthroplasty may be considered for patients with destructive gunshot wound (GSW) injuries. We present a review of two patients who sustained a low-velocity GSW of the hand with involvement of an MCP joint requiring MCP joint salvage using arthroplasty. Differing arthroplasty methods were used for each patient including pyrocarbon hemiarthroplasty and silicone arthroplasty. For pyrocarbon hemiarthroplasty, total arc of motion at 9 months after surgery for the MCP, proximal interphalangeal, and distal interphalangeal joints were 70º, 110º, and 80º, respectively. For silicone arthroplasty, total arc of motion at 9 months after surgery for the MCP, proximal interphalangeal, and distal interphalangeal joints were 85º, 120º, and 80º, respectively. Both patients returned to work without restrictions and were without chronic pain at the last follow-up 9 months from salvage surgery. The application of pyrocarbon or silicone arthroplasty for GSWs is a viable option for joint salvage in this population.
Key words: Gunshot, Joint, Metacarpophalangeal, Trauma, Salvage
Gunshot wounds (GSWs) are a high morbidity injury, and an estimated 32% of all GSWs involve the upper extremity.1 Particularly, involvement of joint surfaces poses a challenge for fracture stabilization and postoperative pain, posttraumatic arthritis, and disability. Primary repair of the joint surface is often not possible given the degree of destruction secondary to the ballistic trauma seen in GSWs. The metacarpophalangeal (MCP) joint is critical to finger function as it is responsible for the majority of total finger arc of motion.2 Current treatment options for traumatic injury of the MCP joint include amputation, arthrodesis, arthroplasty, or vascularized joint transfer, and the appropriate treatment must consider all osseous and soft tissue injuries.2 MCP joint arthroplasty using silicone or pyrocarbon implants may be considered for patients with traumatic joint defects to preserve motion and function.
Case Report
Patient 1
A 23-year-old right-handed man presented after sustaining multiple GSWs to the right hand, anterior torso, and right lower extremity. Radiographic examination showed significant comminution of the radial aspect of the second metacarpal head with involvement of the MCP joint (Fig. 1a). On physical examination, a through-and-through wound overlying the second metacarpal head with an associated fracture was identified. There was no concern for tendinous or neurovascular injury. This wound was thoroughly irrigated and ceftriaxone administered. Following the injury, the patient was followed on an outpatient basis to monitor soft tissue healing and ensure adequate and supple soft tissue coverage of the planned reconstruction. Four months after the initial injury, the patient underwent right second MCP joint salvage with pyrocarbon hemi-arthroplasty. Pyrocarbon hemiarthroplasty was used because the patient had preservation of the base of the proximal phalanx and adequate bone stock within the metacarpal to support the implant. After dorsal access to the MCP joint, obvious eburnation of the comminuted metacarpal head as well as damage and fibrosis of the radial collateral ligaments were identified. After resection of the metacarpal head, a size 30 pyrocarbon metacarpal head implant was placed. Collateral ligaments were then resuspended to the metacarpal neck. Postoperative radiographs are shown in Figure 1b. At the most recent follow-up, approximately 9 months following MCP joint hemiarthroplasty, the patient is without daily limitations and has returned to work. His posttrauma neuropraxia has resolved. Total arc of motion for the MCP, proximal interphalangeal (PIP), and distal interphalangeal (DIP) joints were 70°, 110°, and 80°, respectively (Table).
Figure 1.
A Radiographs for patient 1 at time of presentation with GSW to the second metacarpal head. B Postoperative radiographs following pyrocarbon implant arthroplasty.
Table.
Postoperative Outcomes Following Implant-Based MCP Arthroplasty
| Patient 1 | Patient 2 | |
|---|---|---|
| Age (y) | 23 | 50 |
| Follow-up length (mo) | 9 | 9 |
| Implant type | Pyrocarbon | Silicone |
| Digit | Index | Ring |
| MCP Extension (degrees) | 0 | 10 |
| MCP Flexion (degrees) | 70 | 75 |
| PIP Extension (degrees) | 0 | 10 |
| PIP Flexion (degrees) | 110 | 110 |
| DIP Extension (degrees) | 0 | 80 |
| DIP Flexion (degrees) | 80 | 0 |
Patient 2
A 50-year-old right-handed man presented with accidental GSW to the left fourth metacarpal. Radiographic examination showed significant comminution of the head and neck of the fourth metacarpal with extension into the MCP joint (Fig. 2a). On physical examination, a through-and-through wound overlying the fourth metacarpal was identified. Paresthesia of the ulnar digital nerve was present. The patient was brought to the operating room for exploration of the wound and open reduction and internal fixation of the metacarpal. Because of extensive comminution of the head and neck, fixation was limited to spanning Kirschner wires from the fifth metacarpal head to the fourth metacarpal head to maintain fracture length. There was no evidence of digital nerve injury despite the physical examination findings. The Kirschner wires were removed four weeks after surgery. Following Kirschner wire removal, the patient exhibited pain with motion at the fourth MCP joint. There was also radiographic evidence of proximal phalanx subsidence at the MCP joint. After allowing bony healing for 4 months, MCP joint salvage using silicone arthroplasty was performed. A silicone arthroplasty was chosen because the patient had cartilaginous damage to the base of the proximal phalanx with associated ligamentous injury. A dorsal approach was used to access the MCP joint with release of the collateral ligaments from the remaining metacarpal head. There was evidence of arthritic and adhesive disease within the proximal and distal joint surfaces. After resection of the metacarpal head and base of the proximal phalanx, a size 4 silicone implant was placed. Collateral ligaments were then resuspended to the metacarpal neck. Postoperative radiographs are shown in Figure 2b. At the most recent follow-up, approximately 9 months following MCP joint arthroplasty, the patient is without daily limitations and returned to work. Regarding range of motion, total arc of motion for the MCP, proximal interphalangeal (PIP), and distal interphalangeal (DIP) joints were 85°, 120°, and 80°, respectively (Table).
Figure 2.
A Radiographs for patient 2 at time of presentation with GSW to the fourth metacarpal head and neck. B Postoperative radiographs following silicone implant arthroplasty.
Discussion
MCP joint disruption secondary to trauma is a difficult injury to manage and is commonly complicated by pain, disability, and posttraumatic arthritis.3 Bony stabilization with prolonged immobilization and MCP joint arthrodesis are plagued by hardware failure concerns and limitations in hand function.3,4 Here, we presented two case reports that identify GSWs as a cause of MCP joint injury and highlight arthroplasty as a means of joint salvage in these cases. The literature regarding MCP joint salvage in cases of untreatable MCP joint destruction is often limited to degenerative, rheumatoid, and nonballistic traumatic indications.4
As a method of MCP joint salvage, arthroplasty with either conventional silicone implants or newer, pyrocarbon implants is the most common approach reported in the literature. Silicone based arthroplasty has been traditionally applied to MCP joint pathology secondary to osteoarthritis or rheumatoid arthritis with reasonable success.5 Despite this procedure’s reliability, significant literature exists regarding concern for late implant failure, silicone synovitis, and infection risk. Similarly, pyrocarbon-based arthroplasty has successful historical data for the treatment of arthritic pathologies of the MCP joint.6 Proponents of pyrocarbon implants cite its similar elastic modulus to bone and decreased failure rates compared to silicone arthroplasty.
Data for these two methods of MCP joint arthroplasty in the posttraumatic setting are however limited. The classic report by Nagle et al7 on posttraumatic silicone arthroplasty for PIP and MCP joint injury demonstrated reliability of silicone implants in this setting with adequate range of motion (ROM) maintenance. Other investigations confirm these results with MCP active ROM range of 48° to 54° degrees following posttraumatic silicone arthroplasty.8 For pyrocarbon-based arthroplasty following trauma, the results are similarly encouraging. Houdek et al4 showed pyrocarbon arthroplasty used in the acute posttraumatic setting to be safe and effective. Mean MCP total ROM was 56° (range, 30° to 70°), and 86% of patients exhibited mild or absent pain after surgery. Of note, one patient sustained intraoperative fracture during implant placement. Pyrocarbon implant placement is prone to intraoperative fracture because of the requirement of press fitting, but there is no current concern for long-term implant survival if intraoperative fracture does occur.4 Other prior investigations of pyrocarbon implant arthroplasty following traumatic injury are limited to proximal interphalangeal joint salvage and report similar ROM outcomes to silicone implant arthroplasty.9
The cases presented here used both silicone and pyrocarbon implant arthroplasty with satisfactory results. The decision to use one technique versus the other is based on preservation of the base of the proximal phalanx and surrounding ligamentous support. In cases where there is no concern for proximal phalanx injury and there is adequate metacarpal stock, pyrocarbon implant provides stable, long-term reconstruction. The average MCP joint ROM following arthroplasty for treatment of arthritic conditions is 50° to 70°.3,10 In this case series, ROM outcomes were similar with 70° and 85° for silicone and pyrocarbon implant arthroplasty, respectively. As recommended by Houdek et al,4 collateral ligament resuspension with absorbable suture was used in these cases and is advised to preserve joint stability. At final follow-up, both patients have returned to work without significant limitation despite the gravity of their initial injuries. As evidenced by the literature and our case series, posttraumatic MCP joint arthroplasty is a reasonable option for joint salvage. This report provides new context for these techniques in MCP joint salvage following GSW to the hand.
GSWs to the hand can present with difficult to treat traumatic defects of the MCP joint. MCP joint salvage with silicone or pyrocarbon arthroplasty is a viable option for these scenarios. ROM and function outcomes in posttraumatic MCP joint arthroplasty approximate the outcomes observed in reconstruction of the arthritic joint. Further comparative investigations between these two implant options in traumatic joint reconstruction are needed.
Conflicts of Interest
No benefits in any form have been received or will be received related directly to this article.
Footnotes
Informed consent was obtained from all patients for being included in the study.
References
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