Dorsal Capsule Interpositional Arthroplasty of the Metacarpophalangeal Joint

Abstract

Background: Current recommendations for osteoarthritis of the metacarpophalangeal joint (MCPJ) are confined to implant arthroplasty to preserve joint motion and provide pain relief. This study documents the median 2-year results of a novel soft tissue arthroplasty technique that interposes the dorsal capsule. Methods: A retrospective review of 10 MCPJ dorsal capsule interposition arthroplasties in 8 patients was conducted. Physical evaluation assessed MCPJ range of motion (ROM), grip strength, and pain. Outcome tests used were the Michigan Hand Outcome Score, Visual Analog Scale (VAS), and Quick Disabilities of the Arm, Shoulder, and Hand (QuickDASH). Kellgren and Lawrence Classification assessed severity of MCPJ osteoarthritis on preoperative radiographs. Results: The mean follow-up was 29 months from surgery. Average VAS was 2/10 postoperatively and average postoperative ROM improved 7 degrees. Average postoperative grip strength of the surgical hand was 30 kg. The QuickDASH average score was 24. Average Michigan Hand Questionnaire final score was 70. Patients with Kellgren Grades 2 or 3 osteoarthritis had the best QuickDASH and Michigan Hand Outcome scores. All patients working before surgery returned to work. No patient required a second surgery. Conclusion: This technique of dorsal capsule interposition arthroplasty provides a viable surgical option for isolated degenerative or traumatic arthritis of the MCPJ at an average follow-up of 2 years. Pain relief was most reliably provided in patients with less severe radiograph findings. The advantages of this procedure include preservation of bony anatomy, collateral ligaments, and volar plate to not preclude later implant arthroplasty.

Introduction

Osteoarthritis of the metacarpophalangeal joint (MCPJ) results in disabling pain when the hand is used for gripping objects into the palm. Currently, there are 2 primary surgical techniques in addressing this condition: arthrodesis and implant arthroplasty.^1-4 Arthrodesis, or fusion of the joint, provides pain relief but prevents the finger from bringing objects into the palm. Implant arthroplasty relieves pain while preserving motion with implants made of silicone, ³ metal on plastic, ⁵ or polycarbonate. ² A long-term follow-up study ⁶ of over 1000 implanted joints showed an implant fracture rate of 42% at 10 years and 66% at 17 years. Revision rates were 17% at 10 years. However, implant arthroplasty is currently the standard of care when surgically addressing MCPJ osteoarthritis as “no better options exist at this time that will preserve motion and relieve pain for small-joint osteoarthritis.” ⁷ The purpose of this study is to evaluate the short-term clinical results of dorsal capsule metacarpophalangeal interposition arthroplasty performed in patients with osteoarthritis of the MCPJ.

Soft tissue interposition arthroplasty is a surgical technique where the patient’s native tissue is used between the arthritic bones of an affected joint. This technique has been studied in the hand, ⁸ wrist, ⁹ and elbow. ¹⁰ Previous studies^11,12 have examined soft tissue interposition in the MCPJ in rheumatoid arthritis patients. Riordan’s review of the multiple methods of soft tissue interposition cited the technical difficulties of these techniques and dubious results due to the bone resection required to repair the supporting ligaments or tendon alignment. ¹³ Almost all these techniques utilized the stout volar plate for interposition tissue, requiring resection of the metacarpal head or base of the proximal phalanx.^11,12,14-16 Anatomic studies have shown that the dorsal joint capsule has the same histological composition of the stout volar ligament. ¹⁷ The consistent, thick, triangular cartilage, as well as the greater length of the dorsal capsule to accommodate flexion, makes the dorsal joint capsule an attractive option for interposition. Subsequently, we developed a novel interposition arthroplasty technique for isolated MCPJ osteoarthritis in the cadaver lab.

The first patient in this series was offered this novel technique following septic arthritis of his MCP joint. Pain, radiographic joint changes, and limited range of motion (ROM) of the third MCP joint severely affected the patient’s hand function. Successful treatment with this technique led us to offer this procedure in active patients with isolated MCP osteoarthritis who failed conservative treatment, including intraarticular steroid injections, activity modifications, and antiinflammatory drugs.

Methods

Surgical Technique

Dorsal curvilinear incision around the MCP head allows mobilization and longitudinal incision of the extensor tendon (Figure 1). A distally based capsule flap is created and elevated off the metacarpal head (Figure 2). Cheilectomy was performed only when osteophytes interfered with ROM. If cheilectomy was performed, consideration of bone wax over the exposed cancellous bone will decrease postoperative bleeding and potential hematoma formation. The collateral ligaments are released as needed from dorsal to volar to gain desired flexion without destabilizing the joint. A volar incision in the palm (Figure 3) is made to release the A1 pulley and expose the volar plate by retracting the 2 flexor tendons. A stay suture is then passed through the free limb of the capsule flap and delivered through the volar plate in a dorsal to palmar direction using a Keith needle (Figure 4). The capsule is then pulled into the joint by the suture, tying the 2 suture ends onto the palmer surface of the volar plate (Figure 5). The extensor tendon is repaired (Figure 6) and skin closed. Radial gutter splint in the intrinsic plus position is applied. At a 7- to 10-day postoperative visit, the sutures were removed. Active and gentle active assisted ROM of the MCP joint is started with hand therapy when the wound is healed. A forearm based, dorsal MCP blocking splint for the radial 2 joints to maintain at least 60 degrees of flexion is worn for 6 weeks. Passive ROM and strengthening is added at 6 weeks.

Figure 1.

Dorsal approach allows longitudinal split between extensor tendons to index finger, being careful to not cut the underlying capsule. A distally based capsule flap is drawn, taking advantage of the proximal capsule attachment on the metacarpal head.

Figure 2.

Capsular flap is elevated, metacarpal head arthritis is evident. Collateral ligaments are preserved during flap development and can be carefully elevated off the metacarpal attachment if improved joint flexion is needed.

Figure 3.

A palmar Bruner incision allows for the A1 pulley release to mobilize the flexor tendons.

Note. A blunt self-retaining retractor, such as a Heiss, will expose the volar plate of the joint. The suture is then passed from dorsal to volar out through the palmar wound using the Keith needle.

Figure 4.

A 2-0 vicryl is passed through the proximal edge of the flap. A Keith needle is used to pass the suture ends separately from dorsal to volar.

Figure 5.

Sutures are tied on the palmar surface of the volar plate and the joint is ranged passively to ensure the interposed tissue is stable throughout the entire range of motion.

Note. “Bulging” tissue indicates overstuffing the joint with the capsule and the interposition should be revised with shortening of the capsular flap.

Figure 6.

Longitudinal locking whip stitch provides enough strength for immediate active range of motion to help prevent adhesions.

After internal review board approval was obtained, the first 10 patients who underwent the surgery were contacted for postoperative examination. Two of the 10 patients had moved out of state and were unavailable for participation in the study, though both reported satisfaction with their results. The remaining 8 patients, with 10 MCPJ arthroplasties, were examined. Postoperative follow-up included MCPJ ROM, Quick Disabilities of the Arm, Shoulder, and Hand (QuickDASH), Michigan Hand Outcome score, Visual Analog Scale (VAS), grip strength evaluation, and postoperative radiographs using Kellgren and Lawrence classification. ¹⁸

In the clinic, patients were assessed documenting extent of pain relief, joint ROM, radiographic evidence of joint changes, objective strength measurements, and current hand function. Their pain was assessed with a VAS. Active and passive ROM of the operative joint and correlating contralateral hand joint was measured using a goniometer by a hand therapist outside the study. Grip strength of both hands was measured using a Jamar dynamometer at the second rung. Michigan Hand Outcome Questionnaire and QuickDASH Questionnaire were completed by the patient at the follow-up visit. A single posteroanterior radiograph view was performed for comparison to previous radiographs taken at time of surgery.

Statistical Analysis

Statistical analysis was performed using the student’s paired t-test with statistical significance noted at P < .05.

Results

Ten MCP joints from 9 right hands and 1 left hand in 8 males and 1 female underwent dorsal capsule interposition arthroplasty. All were right hand dominant. The mean follow-up period was 29 months (range: 16-43 months). The average patient age was 60 years old (range: 40-76). Mean VAS preoperatively was 8/10 compared to 2/10 postoperatively, a statistically significant improvement (P < .001). Average postoperative flexion improved an average of 7.1 degrees (ranging from 18 degrees loss to 31 degree gain). Average QuickDASH at final follow-up was 25.3 (range: 2.3-61.4). Average operative extremity Michigan Hand final score at follow-up was 70 (range: 44-97). Postoperative grip strength in the surgical extremity ranged from 7.3 to 53.5 kg with an average of 30.2 kg (Supplemental Table S1). All patients working before surgery returned to work. One patient experienced a temporary digital nerve paresthesia from the volar approach that fully resolved in the postoperative follow-up period. No patient required a second surgery.

Discussion

Our study demonstrates that dorsal capsule interposition arthroplasty provides a viable surgical option for mild to moderate osteoarthritis of the MCPJ with Kellegren and Lawrence classification Grade 3 or less. Patients with Michigan Hand pain scores of 50 or less or Kellegren and Lawrence Grade 4 radiographic changes had worse outcomes, whereas patients with Kellgren and Lawrence Grades 2 or 3 had improved QuickDASH, VAS, and Michigan Hand outcome scores postoperatively. The advantages of this procedure include minimal bone loss to not preclude later implant arthroplasty and postoperative joint stability by preserving the volar plate the collateral ligaments. The dorsal capsule interposition arthroplasty may serve as a “bridge” for younger, or more active, patients with higher demands on their hands than current implants can withstand. Our study included patients of all activity and demand levels, including an electrician, handy man, and bus driver. No difference in outcome was observed based on demand.

Our results compare favorably to Wall and Stern’s short-term outcomes of pyrolytic carbon arthroplasty of the MCP joint ¹ (Figure 7). In Wall’s study, similar average VAS score (1/10 in their study to 2/10 in ours, P = .1527), Michigan Hand final scores (80 vs 70 in ours, P = .4099), and QuickDASH (22 vs 24 in ours, P = .8380) were seen over a 4-year mean follow-up period. Operative digit flexion ROM was increased in our study by 7 degrees compared to Wall’s reported 3 degrees average increase in flexion (P = .5128). Our study also demonstrated slightly increased postoperative grip strength of the affected hand with an average of 30 kg compared to their 28 kg (P = .5426). Two patients in their study had persistent squeaking and clicking, another patient reported extensor tendon subluxation, and 1 joint was converted to arthrodesis for unexplained pain.

Figure 7.

Data comparison between dorsal capsule interposition arthroplasty (Walker et al) and pyrocarbon implant arthroplasty (Wall et al).

Note. QuickDASH = Quick Disabilities of the Arm, Shoulder, and Hand; VAS = Visual Analog Scale; MHQ = Michigan Hand Questionnaire.

Unlike prior interposition arthroplasties that utilized the volar plate,^12-17 this technique maintains joint biomechanics; preserves bone anatomy, joint stability, and joint motion; and allows for implant arthroplasty for salvage. Furthermore, this approach avoids the concern of previously described periprosthetic lucency and subsidence seen in implant arthroplasty. ¹ Patients with Kellgren and Lawrence Grades 2 and 3 radiographic changes had better QuickDASH, VAS, and Michigan Hand Outcome scores compared to patients with Grade 4 osteoarthritis where the contours of the bones are altered and likely mechanically degrade the interposed tissue. Patients with more advanced radiographic arthrosis or Michigan Hand Outcome Questionnaire scores less than 50 may be better served with implant arthroplasty. Moraes et al ¹⁹ have shown factors such as coping mechanisms and secondary gains can skew results of surgeries for pain relief. Two of our less successful patients cases involved worker’s compensation and disability application after surgery.

Weaknesses of this study include the small numbers of joints studied as well as the retrospective nature of review. This disease process is uncommon even in busy hand surgery practices ¹⁸ but poses a difficult problem for certain demographics, including a laborer in his fourth or fifth decade who has persistent MCPJ pain despite conservative treatment. This investigation was measured similarly to a comparable study already published in the hand surgery literature that allows for a “historical comparison.” ¹ Longer term follow-up as well as increased numbers of operative joints for evaluation will provide further guidance on the indications and usefulness of this procedure. Further study on the long-term results of this technique is planned.