Surface Replacement Arthroplasty Using a Volar Approach for Osteoarthritis of Proximal Interphalangeal Joint: Results After a Minimum 5-Year Follow-up

Abstract

Background: Surface replacement arthroplasty (SRA) through a volar approach for the proximal interphalangeal (PIP) joint can preserve the integrity of the extensor tendon, which allows early range of motion (ROM) exercise postoperatively. However, a few reports have shown that the PIP ROM tends to decline with longer follow-up. The goal of this study is to assess the results of at least 5 years of follow-up of SRA through a volar approach and also to investigate the cause of deterioration of ROM with time after SRA through this approach. Methods: Eleven fingers with degenerative osteoarthritis that underwent SRA through the volar approach were examined. ROM of the PIP joint preoperation, 1 year after the surgery, and at final follow-up was measured and statistically analyzed. Also, the relationship between PIP ROM and the osteophyte developed postoperatively was examined. Results: The average follow-up period was 7.3 years. The average PIP ROM of the PIP joints was 52.3° preoperatively, 54.1° at 1 year postoperatively, and 31.1° at the final follow-up. PIP ROM at the final follow-up was significantly decreased compared with that preoperatively or at 1 year postoperatively. Also, the development of an osteophyte was negatively correlated with the ROM of the PIP joint at the final follow-up. Conclusions: PIP ROM after SRA through a volar approach has the tendency to deteriorate with a longer follow-up. Development of an osteophyte is considered to be a main risk factor of deterioration in the cases of SRA through a volar approach.

Introduction

When treating osteoarthritis of the PIP joint with a history of persistent pain that has not been relieved in spite of conservative treatment, arthroplasty such as silicone implant, surface replacement arthroplasty (SRA), and pyrolytic carbon arthroplasty are generally used as a surgical option.^{1,2,7,8,15,17} Among them, SRA where the collateral ligament can be preserved is favored, as it results in both a satisfactory resolving of pain and a functional range of motion (ROM) without instability of the PIP joint.^7,13,17,19 Recently, there have been several reports in favor of SRA through a volar approach because it can preserve the integrity of the extensor tendon and, therefore, provides the advantage of early ROM postoperatively.^7,13,14,17 In these reports, favorable outcome with improvement of the ROM of the PIP joint was demonstrated at least in the short follow-up period.

However, a few reports mentioned that the functional ROM of the PIP joint improved by SRA could be maintained for a certain period but tended to decline with longer follow-up.^7,13 Also, development of osteophyte formation after SRA was reported to be a cause of deterioration in ROM of the PIP joint.^7,13

A long-term follow-up study of SRA through a volar approach has yet to be elucidated although a few reports concerning SRA through a dorsal approach are available.^6,11 The goal of this study is to assess the results of at least 5 years of follow-up of SRA through a volar approach and also to investigate the cause of deterioration of ROM with time after SRA.

Materials and Methods

In this study, surgeries on 11 fingers of 9 patients with degenerative osteoarthritis were examined. All patients underwent SRA by a volar approach and had more than 5 years of follow-up (average: 7.3 years, range: 5-14.9 years). The mean age at the time of surgery was 58.7 (range: 49-65) years. In all cases, SRA was performed to both alleviate pain and acquire more extensive ROM of the PIP joint.

A volar approach, otherwise known as a shotgun approach, was used in all cases. A Bruner incision was used, and the flexor tendon sheath of C1, A3, and C2 pulleys was incised. To reflect the volar plate distally, the checkrein ligament was detached and the lateral edge of the volar plate was released from the accessory ligament with the flexor tendons retracted radially or ulnarly. The PIP joint was then hyperextended and shotgun opened while preserving the collateral ligament as much as possible. After resection of the head of the proximal phalanx by microsagittal saw, replacement of the implant was performed. At the end of the procedure, the lateral edge of the volar plate was sutured to the accessory ligament while the A3 pulley was left open. Postoperatively, ROM exercise with the exception of passive extension was encouraged immediately after surgery.

SRA was performed on 3 middle fingers and 8 ring fingers. The implants used for SRA included Ishizuki total finger system (IFS; Nakashima Medical, Okayama, Japan) in 10 cases and self locking finger joint system (SLFJ; Nakashima Medical, Okayama, Japan)⁷ in one case. Both types are composed of Co-Cr-Mo alloy proximal and a ultrahigh molecular weight polyethylene distal component with an anatomic condylar configuration. In the IFS, the stem of each component was cemented, and in the SLFJ, the proximal and distal component was attached to the joint anchor, which was screwed into the canal of the middle or proximal phalanx without cement in advance.

Functional Assessment

To address the time course of clinical results of SRA, ROM of the PIP joint at the preoperation, 1 year after the surgery, and after the final follow-up was measured. Then, comparison between either 2 out of 3 time points was statistically analyzed with Wilcoxon signed-rank test.

Radiographic Assessment

The relationship between ROM of the PIP joint and the osteophyte developed postoperatively was examined. To quantify the osteophyte, using the lateral view of the radiograph of the PIP joint, the area of osteophyte developed volarly of the proximal phalangeal head implant was measured using image analysis software, Osirix, a free and open-source medical imaging software.^5,21 The measured area was divided by the square of the diameter of the middle of the proximal shaft to minimize the effect of individual differences. It was measured 3 times in each joint, and the mean value was defined as the osteophyte ratio (Figure 1). Then the correlation between the osteophyte ratio and the ROM of the PIP joint at the final examination was statistically analyzed with Spearman rank correlation coefficient. A P value of less than .05 was considered statistically significant. Statistical analysis was performed using JMP (SAS Institute Inc, Cary, North Carolina).

Figure 1.

Osteophyte ratio was calculated as b/a². (a) The diameter of the middle of the proximal shaft. (b) The area of osteophyte developed volarly of the proximal phalangeal head implant.

Clinical Complications and Further Surgeries

Postoperative complications including development of an osteophyte, contracture, implant fracture, dislocation, and loosening of the implant were assessed. In this study, contracture was defined as limited ROM of less than 35°. The required procedure of any further surgery was also assessed.

Results

Patient demographics and outcomes of the study are presented in Table 1.

Table 1.

Patient Demographics and Outcomes.

Case	Age	Digit	Implant	Before SRA	Postoperative 1 year		Final follow-up		Further surgery
				ROM	ROM	OR	ROM	OR
1	59	Middle	IFS	−20/90	−30/80	0.148	−45/60	0.435a	Resection of the osteophyte
		Ring	IFS	0/90	−30/70	0.066	−35/70	0.352a	Resection of the osteophyte
2	49	Ring	IFS	−20/70	−30/80	0.013	−35/50	0.241a
3	52	Middle	IFS	−15/70	−10/70	0.050	−10/70	0.033
4	65	Middle	IFS	−20/50	−20/80	0.119	−15/70	0.090
5	62	Ring	IFS	−10/35	−25/80	0.044	−30/80	0.027
6	56	Ring	IFS	−30/80	−5/75	0.229	−10/35	0.377a
7	65	Ring	IFS	−15/70	−20/80	0.240	−35/35	0.581a
8	53	Ring	SLFJ	−15/65	−20/80	0.157	−30/80	0.159
9	65	Ring	IFS	−15/65	−40/80	0.122	−60/80	0.149a
10	61	Ring	IFS	−20/70	−35/85	0.197	−50/55	0.421a

Note. SRA = surface replacement arthroplasty; ROM = range of motion; OR = osteophyte ratio; IFS = Ishizuki total finger system; SLFJ = self locking finger joint system.

^aSeven fingers developed osteophytes with deterioration of the ROM.

Functional Assessment

The average ROM of the PIP joints was 52.3° (range: 25-90) with average extension/flexion of −16.4/68.6° preoperatively, 54.1° (range: 40-70) with average extension/flexion of −24.1/78.2° at 1 year postoperatively, and 31.1° (range: 0-60) with average extension/flexion of −29.4/60.6° at the final follow-up. Statistically, ROM of the PIP joints at the final follow-up was significantly decreased compared to that measured preoperatively or at 1 year postoperatively (P value was .04 and <.01, respectively).

Radiographic Assessment

The radiographic evaluation revealed that the average osteophyte ratio was 0.126 (range: 0.013-0.240) at 1 year postoperatively and 0.26 (range: 0.027-0.581) at the final follow-up, respectively. Statistical analysis revealed that the osteophyte ratio at the final follow-up was negatively correlated with the ROM of the PIP joint at the final follow-up (R = −0.83, P < .01) (Figure 2). Also, at the final follow-up, a significant negative correlation between osteophyte ratio and flexion of the PIP joint (R = −0.70, P = .02) was recognized (Figure 3), although no significant correlation between the osteophyte ratio and extension of the PIP joint was recognized. However, at 1 year postoperatively, no significant correlation between the osteophyte ratio and ROM, flexion, or extension of the PIP joint was recognized statistically.

Figure 2.

Scatter diagram showing the negative correlation between osteophyte ratio and the ROM of the PIP joint at the final follow-up (R = −0.83, P < .01).

Note. ROM = range of motion; PIP = proximal interphalangeal.

Figure 3.

Scatter diagram showing the negative correlation between osteophyte ratio and the flexion of the PIP joint at the final follow-up (R = −0.70, P = .02).

Note. PIP = proximal interphalangeal.

Clinical Complications and Further Surgeries

In all cases, implant fracture, dislocation, and loosening of the implant were not recognized in the follow-up period. Seven fingers (64%) developed osteophytes in the postoperative period. Joint contracture was recognized in 6 fingers (55%), all of which accompanied development of an osteophyte. Further surgeries were performed on 2 fingers (18%) of one patient who suffered from both flexion pain and decreased ROM as the osteophyte developed in the postoperative period. Resection of the osteophyte both alleviated pain and improved the ROM by 30° and 15°, respectively (Figure 4).

Figure 4.

Radiograph showing the middle finger with development of an osteophyte that required further surgery. (a) Radiograph just after surface replacement arthroplasty. (b) Radiograph 45 months’ postoperatively demonstrating development of osteophyte formation. (c) At most recent follow-up (10 years after resection of the osteophyte), further development of the osteophyte was not recognized.

Case Reports

Representative clinical cases of SRA are shown in Figures 5 and 6.

Figure 5.

Case 7. A 65-year-old woman with osteoarthritis of the proximal interphalangeal (PIP) joint on her ring finger. (a) Preoperative radiograph demonstrating primary osteoarthritis of the PIP joint. (b) At 1 year postoperative, radiograph showed the osteophyte ratio was 0.24. The extension and flexion of the PIP joint were −20° and 80°, respectively. (c) Radiograph 77 months’ postoperatively demonstrated development of an osteophyte on the volar aspect of the PIP joint (arrow), whose osteophyte ratio was 0.58. The PIP joint resulted in ankylosis at 45°.

Figure 6.

Case 4. A 65-year-old woman with osteoarthritis of the proximal interphalangeal (PIP) joint on her ring finger. (a) Preoperative radiograph demonstrating primary osteoarthritis of the PIP joint. (b) At 1 year postoperative, radiograph showed the osteophyte ratio was 0.12. The extension and flexion of the PIP joint were −20° and 80°, respectively. (c) Radiograph 84 months’ postoperatively did not show any further development of an osteophyte whose osteophyte ratio was 0.09. The extension and flexion of the PIP joint were −15° and 70°, respectively.

Discussions

In treating osteoarthritis of the PIP joint, many reports have shown that prosthetic arthroplasty demonstrates favorable clinical results, whereas the rate of its complication including postoperative contracture was reported to be 15% to 65%.^{3,7,9,12,13,16,17,20} Sweets et al showed remarkable deterioration of postoperative ROM after pyrolytic carbon resurfacing arthroplasty where the best postoperative ROM was 67° on average at a mean of 11.6 months postoperatively, but it decreased to 31° on average at an average of 55 months of follow-up.¹⁶ They therefore concluded that they would no longer perform this surgery. This suggests the possibility that the mobile PIP joint acquired by prosthetic arthroplasty will not necessarily be maintained for years. To assess this problem, a long-term follow-up study is essential.

As far as a long-term follow-up of SRA is concerned, only a few reports have documented this. Jennings et al reported a 9.3-year follow-up and showed that the mean ROM of the PIP joint was 64° 3 years postoperatively, but it deteriorated to 56° at the final examination.⁶ Murray et al reported an 8.8-year follow-up and showed that the mean ROM of the PIP joint was 47° 4.5 years postoperatively, but it deteriorated to 40° at the final examination.¹¹ Patients in both studies were treated with dorsal approach; and therefore, there is the possibility that the cause of deterioration of ROM of the PIP joint after SRA using the dorsal approach was mainly extensor tendon dysfunction such as adhesion and attenuation.^12,13

However, the volar approach offers the advantage of maintaining the integrity of the extensor mechanism and allowing early postoperative motion, and therefore, it has been considered to obtain better ROM of the PIP joint at least in the short follow-up period.^4,7,14,17 When limited to primary osteoarthritis of the PIP joint, Trumble et al reported 21 patients who underwent SRA through the volar approach and the average ROM of the PIP joint improved from 58° preoperatively to 87° at an average of 34 months of follow-up.¹⁷ However, long-term follow-up of SRA through the volar approach for primary osteoarthritis of the PIP joint alone has not been reported. In this report, the average of 7.3 years of follow-up of the ROM of the PIP joint was shown. The results showed that the ROM was 54.1° 1 year postoperatively, but it deteriorated to 31.1° at the final follow-up, although no complications other than development of osteophyte were recognized. The cause of deterioration of the ROM must be considered to be different from that via the dorsal approach because extensor tendon is not explored in the volar approach. We investigated whether the osteophyte developing around the implant in the postoperative period affected deterioration of the ROM. On average, the osteophyte increased with time after SRA, and also the ROM, especially the flexion arc of the PIP joint, decreased in correlation with the developing osteophyte. Thus it is speculated that deterioration of the ROM of the PIP joint after SRA using the volar approach is caused by flexion impingement between the base of the middle phalanx and the osteophyte that develops volarly of the implant. This speculation is supported by the fact that the 2 fingers with postoperative contracture after SRA in this series recovered after further surgery of resection of osteophyte.

This report showed that the finger that underwent SRA followed one of two patterns of postoperative course in the longer follow-up period. In one pattern, the ROM that was improved by SRA could be maintained permanently without development of an osteophyte. In the other pattern, the ROM deteriorated in conjunction with the volume of the developing osteophyte even 1 year after SRA. Regarding the cause of development of osteophyte, Mashhadi et al discussed that it might be due to ongoing osteoarthritis.⁹ Komatsu et al pointed out that the molecular mechanism of the heterotopic bone formation has not yet been elucidated, but basic research has demonstrated mechanical stimuli or biomechanical stimuli or both could play a role.^7,10,18 However, it still remains difficult to predict preoperatively which pattern the affected finger will follow. In our series with more than 5 years of follow-up, 7 out of 11 fingers developed osteophytes with deterioration of ROM using the IFS or SLFJ implant. As compared with the previous report where other SRA implants were used, Daecke recognized a 39% rate of osteophyte formation and an 8% rate of complete ankylosis in SR-PIP implants at an average of 35 months of follow-up.² The rate of osteophyte formation in this series was higher, but we postulate that additional fingers in other reports would have development of osteophyte with a longer follow-up. Otherwise, there is a possibility that surgical procedures would be affected. Both of the implants used in this series require scratching the volar condyle of the proximal phalangeal head to fit the proximal component, which could be a cause of osteophyte development. In the future, comparative studies among implants could resolve this issue.

We conclude that ROM of the PIP joint after SRA has the tendency to deteriorate with a longer follow-up on average and development of osteophyte is considered to be a main risk factor for deterioration in the case of SRA through a volar approach.

This study has some limitations. First, it is a retrospective study. Second, a relatively small sample was included. Therefore, a large sample would provide more convincing long-term outcome of SRA through a volar approach. Third, deterioration of ROM of the PIP joint after SRA through the volar approach was shown to exist in this study, but the implants used in this study should be compared with other surface replacement implants. Finally, the measurement of the volume of the osteophyte developed after SRA was limited to the volar part of the proximal phalanx. That of the dorsal part of PIP joint or the volar part of the middle phalanx could affect the ROM of the PIP joint.