Comparison of three different postoperative treatment options after interposition arthroplasty of the thumb, an observational study

Abstract

Background

In rhizarthrosis the saddle joint of the thumb is affected. Occupational therapy after interposition arthroplasty is of particular importance and a key factor for a successful outcome. Orthosis use and/or the timeline of using the orthosis is still under debate.

Research questions:

• In patients with rhizarthrosis after interposition arthroplasty, what is the effect of an orthotic thumb device compared with no orthotic thumb device during accompanying occupational therapy?

• In patients with rhizarthrosis after interposition arthroplasty, what is the effect of a long orthotic thumb device compared with a short orthotic thumb device during accompanying occupational therapy?

Methods

Forty-two patients with confirmed symptomatic rhizarthrosis after interposition arthroplasty by Weilby and 2 weeks cast fixation were randomly assigned to one of the following study arms: Group I: long orthotic thumb device, Group II: short orthotic thumb device, Group III without orthotic thumb device for 4 weeks, accompanied by 12 weeks postoperative occupational therapy. After 6 and 12 weeks, VAS-Pain-Score, Quick-DASH, pinch-and grip-strength, and ROM were evaluated.

Results

All groups improved in their hand functions 12 weeks after surgery. The VAS-pain-score improved by 5 points. The Quick-DASH score halved for patients with short or no orthotic thumb device. Patients with the short orthotic thumb device showed the highest rate of improvement (pain, QuickDASH, mobility of the carpometacarpal joint in abduction, interphalangeal joint mobility, and thumb function) 12 weeks after surgery, followed by the non-orthotic thumb device-group. Non-orthotic thumb device patients did not show higher pain levels. Patients of the long orthotic thumb device-group showed more impairment of their function (pain, grip- and pinch strength compared to the other groups, 12 weeks after surgery).

Conclusion

After interposition arthroplasty of the thumb followed by two weeks cast fixation, a thermoplastic short orthotic thumb device should be used. The short orthotic thumb device only restricts motion of the operated first carpometacarpal joint, leaving all other joints of the thumb moveable for 4 weeks. This recommendation is based on the results obtained 12 weeks after surgery.

Trial registration

Not applicable because this is the publication following a thesis in Austria. At the time of the start of the study, there was no need for registration for such studies in Austria.

Background

Rhizarthrosis is affecting the saddle joint of the thumb, which is subject to particular wear and tear as a result of the physiological aging process or one-sided professional activities [1]. With the progression of the disease, rhizarthrosis’ patients present loss of grip- and pinch-strength which leads to difficulties in hand function and a reduction in the quality of life [2]. The patients concerned are usually still actively working. When non-surgical treatment was performed, but the situation did not improve, so the time factor of rehabilitation and restoration of daily activity after surgery becomes more important. After interposition arthroplasty of the thumb, patients are unable to work for about 16 weeks. The recovery of unrestricted movement for all household activities are defined as at least twelve weeks [3, 4]. Occupational therapy after hand surgery is of particular importance, decisive for the rehabilitation process and a key factor for a successful outcome. It can significantly shorten the time patients are off work. The treatment algorithm is determined by the components of pain, reduction in strength, and the impairment of hand function [5].

Most occupational therapy devices are made individually for each patient. Orthotic thumb devices, described in the literature, usually encompasses both the metacarpophalangeal (MCP1) as well as the saddle joint combined with a fixation of the wrist joint [6]. Depending on the individual design, sometimes the interphalangeal (IP) joint of the thumb may also be included [6]. A key feature of the postoperative orthotic thumb device is to keep the first metacarpal bone in a sufficient abducted position during the early postoperative healing process [6]. The common goal of various types of orthotic thumb devices is the stabilization of the carpo-metacarpal-1 (CMC1) joint in a neutral position and to prevent it from painful movements [7, 8]. The splinting is described for conservative treatment [7, 9,10,11] however comparison of different orthotic thumb devices are scarce [2, 9, 11] and used for conservative treatment only [2, 9, 11]. Tsehaie used 2 different orthotic thumb devices after surgery, one after the other [12]. Comparison of different orthotic thumb devices after surgery were not found in the literature and is the subject of the study reported here. Using the right orthotic thumb device could reduce rehabilitation time. Defining one orthotic thumb device as performing superior of the other could be included in guidelines and could facilitate the decision of the treating surgeon. The focus of the manuscript is the comparison of two different aftertreatment options including orthotic thumb devices compared to no orthotic thumb device following resection suspension arthroplasty in patients suffering from rhizarthrosis.

Literature on postoperative rehabilitation time frame after interposition arthroplasty of the first carpometacarpal joint (CMC1) described that a shorter period of immobilization and an early start of hand therapy can be used without resulting in poorer outcomes or complications [12, 13]. Shorter immobilization allows the patient to quickly return to daily activities during their rehabilitation. Different periods of postoperative immobilization after interposition arthroplasty of the thumb are described, cast immobilization varies between 0–5 weeks, while the total immobilization period varies between 2–12 weeks postoperatively [12, 13]. Until now different protocols for the rehabilitation regarding time of rehabilitation and kind of orthotic thumb device were used. The presented study standardizes the rehabilitation protocol with only varying the orthotic thumb device.

The research questions are:

• In patients with rhizarthrosis after interposition arthroplasty, what is the effect of an orthotic thumb device compared with no orthotic thumb device during accompanying occupational therapy?

• In patients with rhizarthrosis after interposition arthroplasty, what is the effect of a long orthotic thumb device compared with a short orthotic thumb device during accompanying occupational therapy?

Methods

Ethical approval was obtained from the Vinzenz Group Ethics Committee Vienna (EK52/2020). Written informed consent was obtained from each participant before the study. The study was conducted in accordance with the Declaration of Helsinki.

Patients with symptomatic rhizarthrosis who presented in the hospital were included prospectively in the study. Patients with involvement of the scaphotrapeziotrapezoid joint according to stage IV were excluded. There was no age limit for inclusion. All patients were treated with an interposition arthroplasty of the CMC1 joint described by Weilby et al. [14] between October 2020 and October 2021. All patients who met the inclusion criteria and agreed to take part in the study during this time (45 patients) were assigned sequentially to one of the three study groups. No blinding was possible because the patients see which orthosis/no orthosis they get. The evaluating surgeon only saw the digital results, not the patient. They were treated (surgery and occupational hand therapy) at the Orthopaedic Hospital Vienna-Speising in a day clinic setting.

All patients were operated on by the first author under general anesthesia. From a volar approach the trapezium was excised. To prevent instability and proximal migration of the first metacarpal bone, a radial strip of the flexor carpi radialis tendon (FCR) was woven between the remaining intact FCR and the abductor pollicis longus tendon at the base of the first metacarpal bone. The tendon construct was secured with resorbable sutures. After wound closure and sterile dressing, a thumb spica cast (Fig. 1a) which only fixed the thumb in his saddle- and base (MCP1)-joint, without restricting the wrist, was applied to avoid postoperative pain peaks, scar problems and disturbance of the initial wound healing process. Patients of all groups had accompanying occupational therapy for 12 weeks after surgery.

Fig. 1

Fixation after surgery: a: thumb spica cast, which only fixed the thumb in its saddle- and base (MCP1)-joint, without restricting the wrist to avoid postoperative pain peaks, scar problems and disturbance of the initial wound healing process. b: The long orthotic thumb device (group I), which includes and stabilizes the operated CMC1- and the first metacarpophalangeal (MCP1)-joint and ends halfway at the level of the proximal phalanx. c: The short orthotic thumb device (group II), which only includes and stabilizes the operated CMC1-joint and ends up just before the flexion crease of the MCP1-joint so that there was no limitation of the movement of the MCP and IP-joints of the thumb

Forty-five patients were assigned randomly to one of the three study arms (15 subjects per study arm) and treated after interposition arthroplasty and an initial two weeks cast fixation (Fig. 1a), either with a “long” orthotic thumb device (Group I, Fig. 1b), with a “short” orthotic thumb device (Group II, Fig. 1c) or without any orthotic thumb device (group III) for the following 4 weeks. Different orthotic thumb devices were used in our hospital at the decision of the treating orthopedic surgeon. Each orthotic thumb device has its advantages and disadvantages. The subjective impression of the surgeons that one orthotic thumb device is superior to the other or even no orthotic thumb device is the rehabilitation of choice was a matter of debate in our hospital and the presented study was designed to investigate this question objectively. Both types of orthotic thumb devices were made by the treating occupational therapists, each for the patient treated. The long orthotic thumb device includes and stabilizes the operated CMC1- and the first metacarpophalangeal (MCP)1-joint and ends halfway at the level of the proximal phalange (Fig. 1b). There is no restricted movement of the IP-joint. The short orthotic thumb device only includes and stabilizes the operated CMC1-joint without bridging MCP1 joint so that there was no limitation of the movement of the MCP- and IP-joints of the thumb (Fig. 1c). The length of the treatment with casts (for all 2 weeks) and orthosis/or no orthosis (4 weeks) was the result of the experience of the treating surgeon and reflects time frames described in the literature [12, 13]. The occupational therapists instructed the patient how to move digital, elbow and wrist joints to prevent stiffness. At the visit 2 weeks postoperatively, the cast and the skin sutures were removed, a thin wound dressing was applied. All patients had five concomitant occupational therapy visits with the same physiotherapist during the following 10 postoperative weeks. Duration of one therapy session was 30 min. Coordinative exercises including pinch grip exercises and mobilization of all finger joints and the operated CMC1 joint were performed. Patients assigned to the orthotic thumb device groups had to wear the orthotic thumb device permanently for 4 weeks. Patients of group III were instructed only to extend the range of motion of the thumb if the pain level is not increasing. Lifting heavy things (> 5 kg) or pinching under load was generally not recommended. Within the first two occupational therapy visits the focus was on mobilization of the thumb, oedema reduction, and skin care. After wearing the orthotic device for 4 weeks, patients then removed their orthotic thumb device completely and were allowed to resume all daily activities. The same instructions were given to patients of the non-orthotic thumb device group on this visit. During the following 6 weeks, patients had two further occupational therapy visits including the final visit, 12 weeks post-surgery.

Analyzed data were acquired pre-surgery and 6- and 12 weeks post-surgery by the occupational therapists, thus there was no blinding for surgeon performing the post-surgical visits. Quantitative data were VAS pain score, Quick-DASH, grip- and pinch-strength (tip-pinch, JAMAR Dynamometer for pinch- and grip-strength), ROM of MCP1-, CMC1- joint mobility and IP1-joint at 10° and 70° because of irritation of the orthosis to measure the IP-joint and CMC1 mobility. Qualitative data were swelling (when the cast or the orthotic thumb device was getting too tight), irritation of the skin itself or skin nerves and daily activities. Qualitative and quantitative data were obtained by questionnaires or by assessment of the treating occupational therapist.

Data analysis

Three patients in the long orthotic thumb device group had to be excluded because they did not appear at post-surgery visits. Therefore they were excluded from the whole study. 42 patients were analyzed for this study. Due to the small number of patients gender specific calculations could not be performed. Additionally there was no adjustment for confounders for the same reason. Results were analyzed using the program OriginPro (Version 2022, OriginLab Corporation, Northampton, MA, USA). For statistical analysis of continuous variables Kruskal–Wallis-ANOVA was performed, for categorial variables Chi-Square test was performed. To check normal distribution of data the Shapiro–Wilk-test was used. A p-value of < 0.05 was assigned as significant differences. Subgroups (gender/smoker) and confounders (gender, smoker, age, dominant hand) were analyzed but did not give any differences.

Results

A total of 50 patients were assessed for eligibility, Forty-five patients were included in the study, fulfilling inclusion criteria. Three patients in the long orthotic thumb device group were lost to follow-up. This could be due to poor outcome, but the reasons are not clear. Due to this fact a bias in data interpretation could not be excluded. The results of the long orthotic thumb device are worse, even without the data of these 3, thus the exclusion of these 3 patients did not impact the general outcome. Forty-two patients completed the follow-up visits. The follow-up time was 12 weeks. Table 1 provides demographic characteristics of the patients who completed the study. The majority were female patients (78%). We did not use the intention to treat analysis, because the data we analyze are follow-up data, thus it does not make sense to include patients who did not have even one follow-up. The demographic data of this 3 patients were in the range of the group and would not have changed the data before treatment.

Table 1 Patients demographic

Due to the high number of female patients in all groups an analysis of gender-specific results could not be performed. Most of the patients have the right hand as the dominant hand (93%) but only in 55% of the cases the dominant hand was treated. There were no changes in the originally assigned group. Primary and secondary outcomes are presented in supplemental Table 1.

For answering the research questions and to avoid duplications we present first the results of all three groups together and then draw a conclusion.

VAS Pain Score

VAS pain score (Fig. 2) was similar in all groups before surgery and improved in all three groups after surgery ( paired t-Test). In motion the pain level in the non-orthotic thumb device group and in the short-orthotic thumb device group was lower than in the long-orthotic thumb device group but did not reach statistical significance (Fig. 2a). The improvement of the pain level at rest and at night was significantly higher in the no orthotic thumb device group after 12 weeks and in the short orthotic thumb device group after 6 weeks compared to the long orthotic thumb device group at the time points investigated (Fig. 2b and 2c, Kruskal–Wallis-ANOVA). The highest improvement in pain is during movement, which is the most relevant clinical outcome, because this limits patients in their daily life.

Fig. 2

VAS pain score during movement (a), at rest (b) and at night (c) pre-surgery, 6- and 12-weeks post-surgery. ***p < 0.001, *p < 0.05 vs. pre-surgery; ^$$p < 0.01, ^$p < 0.05 vs. 6 weeks post-surgery; Data are presented as mean ± SD. ^&p < 0.05 vs. long orthotic thumb device

Quick-DASH-Score

The presurgical Quik-DASH score was 48.3, 48.3 and 42.11 for the long-, short and non-orthotic thumb device groups, respectively. The Quick-DASH-Score showed a significant improvement (paired t-Test) in the short- and non-orthotic thumb device group 12 weeks after surgery (25.0, p = 0.00026 and 21.8, p = 0.00018, respectively). Patients treated with the long orthotic thumb device showed no improvement after surgery and significantly (Kruskal–Wallis-ANOVA) worse scores compared to patients of the other two groups (43.7, p = 0.0146 and p = 0.0215 for non-orthotic thumb device and short orthotic thumb device vs. long orthotic thumb device, respectively). The improvement of the Quick-DASH is clinically relevant. Also the difference between the distinct types of orthotic thumb devices is not only statistically relevant but also clinically.

Grip- and Pinch-Strength

Grip-strength (Fig. 3a) was significantly lower before surgery in the short orthotic thumb device group. Grip strength decreased 12 weeks after surgery in the long orthotic thumb device group and in the non-orthotic thumb device group significantly (paired t-Test). Only in the short orthotic thumb device group did the grip-strength reach pre-surgery values. This means that using the right rehabilitation method, the grip strength can reach presurgery values 12 weeks after surgery. This finding is clinically important, because the aim of the treatment is to restore hand function and not to worsen it.

Fig. 3

Grip- (a) and pinch- (b) strength pre-surgery, 6- and 12-weeks post-surgery. Data are presented as mean ± SD. ***p < 0.001, **p < 0.01, *p < 0.05 vs. pre-surgery; ^$$$p < 0.001, ^$$p < 0.01, ^$p < 0.05 vs. 6 weeks post-surgery; ^&p < 0.05 vs. no orthotic thumb device in the pre-surgery group and vs. long orthotic thumb device in the 6- and 12-weeks post-surgery group

The pinch-strength (Fig. 3b) showed nearly similar values in all group’s pre-surgery. 12 weeks after surgery the short orthotic thumb device group and the non-orthotic thumb device group reached preoperative values, whereas the long orthotic thumb device group had a significant impairment of the pinch-strength (Kruskal–Wallis-ANOVA).

Mobility of the carpometacarpal joint (CMC)

In the short orthotic thumb device group, abduction (Fig. 4a) was significantly higher than before surgery. The non-orthotic thumb device group had the highest abduction values but did not reach statistical significance. Extension and opposition did not improve after surgery in comparison to presurgical values (Fig. 4b and d). Flexion did improve after surgery but did not reach statistical significance in the non-orthotic and short orthotic thumb device group (Fig. 4c).

Fig. 4

Mobility: Abduction (a), extension (b), flexion (c) and opposition (d) pre-surgery and 6- and 12-weeks post-surgery. Data are presented as mean ± SD. ***p < 0.001, *p < 0.05 vs. pre-surgery; ^$$$p < 0.001, ^$$p < 0.01, ^$p < 0.05 vs. 6 weeks post-surgery

Metacarpal joint and the interphalangeal joint mobility

The MCP1 joint function did not improve after surgery. The non-orthotic thumb device and the long orthotic thumb device group had a significantly lower ROM-level 12 weeks after surgery (p = 0.0033 and p = 0.016, respectively). The short orthotic thumb device group did reach presurgical values.

The ROM of the IP-joint only improved significantly in the short orthotic thumb device group at 10° (p = 0.043) however decreased significantly at 70° (p = 0.019) 12 weeks after surgery. The other groups showed values in the range of pre-surgery.

Visual subject measures

Visual subject parameters (supplement Table 2) like postoperative swelling, hematoma, sensory disturbances, or skin problems showed no significant differences between the groups at all visits.

Thumb function in daily activities

At all visits (pre-and postsurgery) patients were asked 5 questions to evaluate their integrative thumb function during daily life (Table 2).

Table 2 Questions for integrative thumb function

The ability to turn a key in the lock improved in all 3 groups significantly in comparison to presurgery (Table 3). To tie a shoelace or knot improved significantly in the non-orthotic thumb device group and in the short-orthotic thumb device group, compared to pre-surgical data. Twelve weeks after surgery the ability to tie a knot was significantly better in the short orthotic thumb device group compared to the long orthotic thumb device group. The ability to button a shirt or blouse improved significantly in the non-orthotic thumb device group and in the short-orthotic thumb device group, compared to presurgical data. Unable to work and shorten the workday because of hand problems reduced after surgery but did not reach statistical significance.

Table 3 Summary of outcomes^a (comparison of pre-surgery data with data after 12 weeks)

Summary of outcomes

The short orthotic thumb device group showed the best outcome. Patients in this group improved in 9 categories, with 2 significantly better than the long orthotic thumb device, 12 weeks after surgery. Additionally, the short orthotic thumb device group showed similar values to presurgery in 8 categories and had worse results after surgery only in the interphalangeal joint mobility at 70°, 12 weeks after surgery.

The non-orthotic thumb device group showed improvements in 7 categories, 12 weeks after surgery, with 2 significantly better than the long orthotic thumb device group. The non-orthotic thumb device group showed comparable results in 9 categories, 12 weeks after surgery and had worse outcomes after surgery in grip strength and metacarpal joint mobility.

The long orthotic thumb device group showed improvements in only 2 categories, 12 weeks after surgery (only in pain during movement and when they turned the key in the lock). In 13 categories there was no improvement, and a worse outcome was reported in 3 categories (for grip- and pinch-strength and for metacarpal joint mobility), 12 weeks after surgery.

Thus, the long orthotic thumb device group had the worst outcome. The statistical difference between the groups did not reach significance (p = 0.07292 between the short and the long orthotic thumb device group).

Research question 1.

? In patients with rhizarthrosis after interposition arthroplasty, what is the effect of an orthotic thumb device compared with no orthotic thumb device during accompanying occupational therapy?

! We propose a(n) (short) orthotic thumb device with accompanying occupational therapy in the course of early postoperative rehabilitation because it improves mobility and function 12 weeks after surgery.

Research question 2.

?In patients with rhizarthrosis after interposition arthroplasty, what is the effect of a long orthotic thumb device compared with a short orthotic thumb device during accompanying occupational therapy?

!There is a trend (p=0.07292) that the short orthotic thumb device group showed better results overall. Regarding pain, strength, function and mobility, the short orthotic thumb device outperformed the long orthotic thumb device group, 12 weeks after surgery.

Discussion

Even though the surgical method is important for the clinical outcome of interposition arthroplasty [15], this study focuses on the postoperative treatment using different orthotic thumb devices. There is little data regarding the postoperative treating process after interposition arthroplasty of the thumb. The literature shows a wide range of after-treatment concepts, starting from nothing up to several weeks of cast immobilization [8, 11, 13].

We suggest to treat patients after interposition arthroplasty with the short orthotic thumb device for 4 weeks after removing the initial 2 weeks cast fixation. The initial 2 weeks cast fixation is necessary to save patients from early postoperative pain and wound healing problems and is similar to results described by Wouters et al. [13]. The main reason for the 6 weeks aftertreatment period is the biological healing and restoration of a strong and stable CMCI joint by natural scare building. Accompanying occupational therapy during the postoperative period is mandatory to resume activities of daily life as fast as possible. A treating period of at least 12 weeks postoperatively has to be calculated. We agree with Marotta et al. [11] that the short orthotic thumb device is best for improving function. But our results contrast the findings of Marotta et al. [11] regarding pain relief. The statement of Marotta, that the pain relieve is higher with the long orthotic thumb device relies on two papers: Cantero-Tellez et al. [16] and Weiss et al. [17] which compare rigid thermoplastic splints (long and short). In both publications the difference is not significant. Additionally, the long orthotic thumb device from Weiss et al. [17] is quite different from ours. The other included papers do not compare rigid short and long thermoplastic devices directly. Bani et al. [7] described a similar pain level as in our study in his osteoarthrosis patients using a custom-made orthotic thumb device. Wouters et al. [13] summarized in their review, that early active recovery (in our case starting 2 weeks after surgery) is used more often in the literature and does not lead to worse or more complications. Our study showed that the natural movements of the musculature are a crucial factor in promoting optimal healing success. Therefore, after the 6th-week postoperatively, the removal of any orthotic thumb device would be recommended in order to counteract the onset of muscle atrophy and possible degeneration of neighboring joints. Regarding the type of the orthotic thumb device, patients with the recommended short orthotic thumb device had less restricted hand function during the postoperative period. An explanation for the better results in the short orthotic thumb device/no orthotic thumb device group could be the faster reduction of swelling and the faster development of the venous and lymphatic restoration, due to more range of motion.

The Quick-DASH values were 25 and 22 for the groups with the short orthotic thumb device and with the non-orthotic thumb device, respectively, which is much better than values reported by Bani et al. with 71 after 90 days [7].

Tsehaie et al. [12] could not find any difference in the VAS pain score and hand function using 4- or 6-weeks orthoses after interposition arthroplasty. The pain score and the pinch- and grip-strength they described were in the same range as observed in our study and also observed by Pogliacomi et al. [8]. The long orthotic thumb device group in our study achieved lower values for the grip- and pinch-strength.

Limitation of the study

The number of patients per group is low. The number of male patients is even lower. Because of the small number of male patients, we could not perform a gender related analysis. The bias was addressed by sequencial distribution of the patients to the groups. Even if we could observe significant differences for single parameters with enough power, we would not call the results a recommendation but a tendency for the optimal treatment for the patients after interposition arthroplasty of the thumb. More research has to be done to confirm these results.

Conclusion

After the surgical intervention of interposition arthroplasty according to Weilby and the subsequent postoperative immobilization of the thumb with a two-week plaster-cast with thumb inclusion, we recommend that the patients should be treated with a short thermoplastic orthotic thumb device to protect the wound area, to reduce pain and to stabilize the operated joint for at least 4 weeks. This orthotic thumb device has no restriction of ROM in the MCP I joint. Therefore patients are able to use the thumb better during this postoperative healing period which has in our study, with a small number of patients, a positive influence on pain relief, swelling and restoration of grip function. After the 6^th-week postoperatively, in uncomplicated healing courses and after a final clinical evaluation, we recommend that further orthotic thumb device usage can be dispensed in order to keep the restoration process to daily live activities as fast as possible. Studies with higher patient numbers should follow to underline the findings of this study.