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Department of Plastic and Reconstructive Surgery, Erasmus MC- University Medical Center Rotterdam, Dr. Molewaterplein 40, 3015 GE, Rotterdam, the NetherlandsDepartment of Rehabilitation Medicine, Erasmus MC- University Medical Center Rotterdam, the Netherlands
While scaphoid excision combined with Four Corner Arthrodesis (FCA) or Proximal Row Carpectomy (PRC) is a commonly-used salvage procedures to treat type two and type three Scapholunate Advanced Collapse (SLAC) and Scaphoid Nonunion Advanced Collapse (SNAC)-induced degenerative arthritis, controversy remains over which treatment intervention provides superior outcomes. We searched for articles comparing a range of motion, grip strength, complications requiring reoperation, conversion to wrist arthrodesis, pain, and disability of shoulder and arm scores between FCA and PRC-treated patients. The risk of bias was assessed using the National Institutes of Health (NIH) quality assessment tool. We performed a meta-analysis using Random-Effects Models. Fifteen articles (10 retrospective, 2 cross-sectional, 1 prospective, and 2 randomized trials) were included. There was no significant difference between PRC and FCA in any of the different outcome measures. The risk of bias was found consistently high across all studies. Despite the lack of high-quality evidence, based on existing literature, we recommend PRC as the preferred choice of treatment because of the simplicity of the surgical procedure, lack of hardware-related complications, and comparable long-term outcomes.
The human wrist is a complex formation with interactions between several small bones and interligamentary connections resulting in a mobile and stable hand function. If left untreated, disruption of this complex anatomical formation can result in degenerative arthritis, severe pain, and eventually progressive loss of hand function. Degenerative wrist arthritis can arise from rheumatoid arthritis or posttraumatic arthritis affecting the radiocarpal and midcarpal joints of the wrist. The scaphoid bone is an important anatomical and junctional link between the proximal and distal carpal bones.
Scapholunate advanced collapse (SLAC) and scaphoid nonunion advanced collapse (SNAC) are the two most common patterns of degenerative wrist arthritis. In 1984, Watson and Ballet first described SLAC as the most common form of degenerative wrist arthritis.
This condition can be attributed to spontaneous osteoarthritis or post-traumatic injury of the wrist. Due to the abnormal distribution of forces across midcarpal and radiocarpal joints, the radioscaphoid joint is affected, which can progress to the capitolunate joint (Figure 1A). SNAC, a condition of advanced collapse and progressive arthritis of the wrist, results from a chronic scaphoid nonunion, mainly originating from traumatic injury (Figure 1B).
When conservative treatment fails, surgical interventions are indicated. Ideal surgical treatment should result in pain relief and good wrist functionality. Currently, no curative therapies exist; however, many treatment options have been developed for symptomatic relief. Traditionally, end-stage SLAC and SNAC arthritis were treated with total wrist arthrodesis (TWA). Although TWA leads to pain relief in most cases, wrist motion is sacrificed. TWA is currently considered a salvage procedure when other therapies fail. However, newer alternatives to TWA include the use of motion sparing arthroplasty implants which are more anatomically aligned, require minimal bone resection, and offer an improved range of motion and grip strength.
Proximal Row Carpectomy (PRC) and Four Corner Arthrodesis (FCA) are the two most common surgical procedures to treat SLAC and SNAC wrists. These treatment modalities are preferred because they address pain and simultaneously preserve ROM. Briefly, PRC is a resection of the proximal carpal row consisting of the scaphoid, lunate, and triquetrum bones. PRC allows the capitate bone to articulate with the lunate facet of the distal radius, creating a new joint formation (Figure 2A). FCA is a resection of the scaphoid bone and arthrodesis between the lunate, capitate, hamate, and triquetrum bones. This procedure aims to fuse the arthritic midcarpal joint and to reduce pressure in the scaphoid fossa, by redistributing the cartilage contact areas to the lunate fossa. FCA can be performed traditionally with screw fixation (Figure 2B) or with a circular plate (Figure 2C) which is used as an alternative fixation method, preferred by few surgeons in comparison to the traditional compression screws. The rationale for both procedures is the redistribution of the force from the scaphoid fossa to the lunate fossa cartilage of the radius since this cartilage is not affected by the degenerative changes. This lunate fossa is spared from degenerative changes as it is protected from incongruent pressure by its tight ligamentous structures, which control a near spherical joint profile with the capitate base. However, it is not more resilient against arthritic changes than other structures in the wrist and can feature in advanced-stage disease. Indications for the use of each operative procedure are listed in Figures 1 and 2. Generally, FCA is essential, if there is midcarpalosteoarthrtitis and the capitolunate joint is affected in the SLAC or SNAC wrist. A disadvantage for choosing PRC might be an incongruity between the capitate and the lunate fossa leading to degenerative changes and pain and eventually to TWA. However, controversy persists over which of the two procedures has the superior functional short-term and long-term outcome. Two systematic reviews have been published on this topic in 2009 and 2015.
Our study, on the contrary, presents the most up-to-date systematic review and meta-analysis on the most important postoperative outcome measures to help guide clinicians in patient selection and preferred operative method and patients in their treatment choice.
The study was designed according to the Cochrane Handbook for Interventional Systematic Reviews and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocols (PRISMA-P).
Comprehensive searches were carried out in Embase, Medline, Pubmed Publisher, Web-of Science, OvidSP, Cochrane Central Register of Controlled Trials (The Cochrane Library, December 2019, issue 12 of 12), and Google Scholar databases for articles published up to December 2019 by using keywords specific to each search engine (Text S1).
Inclusion and exclusion criteria
The main inclusion criteria were studies evaluating one or more of the following postoperative outcomes of PRC and/or FCA for the treatment of SLAC and SNAC wrists: range of motion (ROM), grip strength, complications leading to reoperations, conversion to TWA, Visual Analog Scale (VAS) pain or Disability of the Arm, Shoulder, and Hand Questionnaire (DASH) scores. Only full-text, original articles written in English were considered for inclusion in the study. Studies combining limited 2 or 3 corners with 4 corner arthrodesis versus PRC were excluded. All reviews, conference abstracts, book chapters, letters, case series, and editorials were excluded.
Relevance and inclusion of the articles were screened by two individual researchers (ARA, LSD) who also screened titles, keywords, and abstracts of all considered articles, according to the pre-established criteria. In case of discrepancy, a third author (JMZ) was consulted. After inclusion based on the above parameters, full-text articles were retrieved and reviewed for inclusion. All articles were evaluated using the PICO (Patient/Problem, Intervention, Comparison, Outcomes) method. All included articles were rated for their level of evidence according to an adapted version from material published by the Center for Evidence-Based Medicine, Oxford, UK.
The risk of bias assessment for observational cohort and cross-sectional studies and intervention studies was carried out by two authors (ARA, LSD) using the National Institutes of Health (NIH) study quality assessment tool.
We performed a meta-analysis on the following parameters: ROM, grip strength, complications, conversions to total arthrodesis, VAS pain score, and DASH score. When standard deviations were not reported, we calculated them based on the method described by Hozo et al.
. For continuous outcomes, we performed a meta-analysis using a random-effects model to estimate the pooled mean difference and 95% confidence interval (CI). For dichotomous data, we used the random-effects model to estimate the pooled risk difference. We tested whether the type of surgery influenced the pooled means or proportions by adding the type of surgery as an independent variable and whether the patient characteristics were the same for both types of surgery.
The Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines were followed. A P-value < 0.05 was deemed statistically significant. All analyses were performed with R version 3.6.0 and the Metafor package.
In total, 1619 articles were retrieved and subjected to screening based on the inclusion and exclusion criteria. Only 16 studies met the initial scope of our study (Figure S1). Upon reading the full text, one article was excluded because it only reported outcomes of two and four corner fusions combined. Of the remaining 15 studies, ten were retrospective (Level III), two cross-sectional (Level III-IV), one prospective cohort (Level II), and two randomized controlled trials (RCTs, Level I) (Figure 3A). The minimum number of included patients per study was 20, with a maximum number of 123 patients. The two RCTs had 20 and 26 patients. Despite the differences in the level of evidence due to the study design, all studies were included in the meta-analyses.
In total, 322 FCA and 328 PRC-treated patients were included in the analysis with the mean age of 48 years in the FCA group and 46 in the PRC group (Figure 3B). Mean follow-up ranged from 6 months to 18 years across the studies. The mean follow-up time across all studies was 5.1 years in the FCA and 5.3 years in the PRC group. In the FCA group, 77% were males and 23% females and in the PRC group, 68% were males and 32% females.
Only nine studies reported the number of treated SLAC and SNAC wrists by either PRC or FCA. The majority of the studies included patients with a grade II/III SLAC/SNAC diagnosis. Of the eight studies, two also included patients with SLAC/SNAC grade I. The remaining seven studies did not report on the SLAC/SNAC grading. All studies except three reported on whether the dominant hand was operated. Only seven studies reported on the number of surgeons that operated, and 10 out of 15 studies mentioned the professional who registered outcome measurements and performed additional testing or collected clinical data. The majority of the studies cited using independent observers (5/15), occupational therapists (3/15), and research staff (2/15).
Risk of bias
The risk of bias was evaluated with the NIH tool. The majority of studies were at serious risk due to a poorly defined and specified study population and in some cases from two different countries and different institutions, and the lack of specific inclusion and exclusion criteria (Figure 4). Almost all studies lacked sample size justification, power analysis, or proper statistical methods to adjust for confounders. Outcome measurements were not conducted in a blinded setting in any study.
Active ROM outcomes
In total, 13/15 studies reported on the ROM. Separate extension, flexion, radial deviation, and ulnar deviation values were reported in eight studies. Three of them were excluded from the pooled analysis because of missing SD or statistical analysis.;pl[-5666666666666666 gftr1
In the meta-analysis, we found no significant differences between PRC and FCA in extension -9.35° (-30.72°–12.02°), P = 0.29, I2 = 96%; flexion -5.89° (-17.24°– 5.47°), P = 0.22, I2 = 91%; radial 4.74° (-3.56°–13.03°), P = 0.19, I2 = 94%; or ulnar deviation -2.52° (-10.02°– 4.98°), P = 0.40, I2 = 76%. (Figure 5). High heterogeneity was noted among the studies in all motion exercises (P < 0.01).
Five studies were excluded from the meta-analysis because they reported only either a combined extension/flexion arc
The three excluded studies did not report a significant difference in grip strength between the two groups. All remaining studies (N = 10) reported grip strength as a percentage compared to the contralateral non-operated hand.
In the meta-analysis, no difference was observed in grip strength in FCA-treated patients compared to the PRC group: -0.02 (-0.13 – 0.10), P = 0.74 (Figure 6). High heterogeneity was noted among the studies (P < 0.01, I2 = 89%).
Complications and reoperations
Complications resulting in a reoperation were reported in 12 studies and consisted of pin removal because of migration causing discomfort, carpal tunnel syndrome decompression, tenolysis, hematoma evacuation, Quervain's stenosing tenovaginitis, ulnar impaction, and scar revision. Three studies did not report on complications and reoperation.
The success of FCA partially relies on the successful union between the lunate, capitate, hamate, and triquetrum carpal bones. Adequate union facilitates the start of the rehabilitation process, therefore nonunion can delay this process, eventually affecting long-term outcomes. Nonunion rates were reported in ten studies, exclusively prevalent in FCA-treated patients due to the nature of the operative procedure. Seventeen (8.8%) cases of nonunion were reported among all studies. In some cases, non-union was an indicator for reoperation or conversion to TWA.
In the meta-analysis, we found no significant difference in the number of complications resulting in reoperation between the two groups 0.03 (-0.03–0.10), P = 0.28 (Figure 7). Moderate heterogeneity was noted among the studies (P = 0.04, I2 = 45%).
Conversions to total wrist arthrodesis
Since total wrist arthrodesis is a salvage procedure for failed FCA or PRC, conversion rates were reported in 12 studies, but not reported on in the three remaining studies.
The VAS pain score was used in six studies. However, we could pool only four of these studies, because of missing standard deviations in two articles which separately did not show a significant difference in postoperative pain score between the two groups.
In the meta-analysis, we found pooled postoperative pain scores to be comparable between the two groups -0.24 (-1.19–0.71), P = 0.47 (Figure 9). There was low heterogeneity among the studies (P = 0.27, I2 = 24%).
DASH scores were reported in seven studies; of which three studies were excluded from the pooled analysis because of missing SD.
In the meta-analysis, there was no difference in DASH scores between PRC and FCA treated patients 1.24 (-22.7–24.54), P = 0.88 (Figure 10). High heterogeneity was noted among the studies (P < 0.01, I2 = 92%).
Clinical symptoms in SLAC and SNAC wrists can be variable. Patients can be asymptomatic or have significant wrist pain, reduced grip strength, or limited motion of the wrist joint. Conservative treatment strategies include the use of splints, anti-inflammatory medication, or corticosteroid injections. Surgical therapies are indicated in case conservative treatment fails. Preventive approaches to the underlying cause such as the scaphoid reconstruction of scapholunate interosseous ligament (SLIL) repair can be considered. The scapholunate ligament is important for maintaining carpal stability and a tear of this ligament disrupts the carpal kinematics and can lead to progression of disease.
Non-union of the scaphoid can result in deformities, incongruence, eventually leading to osteoarthritic changes. Scaphoid reconstruction can be considered if there are reliable cartilage surfaces in the radiocarpal joint, the scaphoid or both. SLAC and SNAC-induced degenerative osteoarthritis of the wrist, and the availability of several surgical therapies with different outcomes, can be dazzling for clinicians trying to select the best possible procedure. Options include a prosthetic scaphoid replacement, radial styloidectomy, wrist denervation, and total wrist arthrodesis. Nerve denervation is used to relieve patients of pain by severing the terminal branches of the anterior interosseous nerve or the posterior interosseous nerve and other fine articular branches from the other major nerves crossing the wrist joint. A recent study in 33 patients with a 41-month follow-up showed a 75% reduction in pain levels.
Whilst this method provides significant pain relief, it does not stop the ongoing osteoarthritis. Early-stage SLAC and SNAC affect the radial styloid and the scaphoid. Radial styloidectomy can be a suitable option for early-stage disease. In more advanced stages of the disease, PRC and FCA are the two most widely used surgical therapies.
Over the last few decades, PRC and FCA have gained popularity and are among the most commonly used procedures to treat degenerative osteoarthritis. Both procedures provide pain relief and preserve ROM; however, because of the lack of RCTs, it remains unclear which procedure provides superior outcomes. We performed a meta-analysis and found no significant difference between ROM, grip strength, reoperation, conversion to TWA, pain, or DASH scores between the two groups. Although nonunion exclusively occurred in the FCA group, it did not affect the reoperation or conversion rate. Only two RCTs exist on this topic and our findings are comparable.
According to Watson, FCA is the preferred treatment option for stage 3 collapse, mainly because the proximal pole of the capitate is involved in the degenerative process, thus excluding PRC as an option. Key question remains whether patients with stage 2 degeneration will have better outcomes with PRC or FCA. In the present study, we included all of the available literature comparing outcomes between PRC and FCA and pooled this data to derive a more robust conclusion. Including only comparative studies was important because of their relatively well-matched study populations and similarity in outcome measurements.
Two systematic reviews are conducted on this topic. Mulford et al. conducted a systematic review comparing outcomes of 160 PRC and 185 FCA procedures.
Their findings demonstrate that grip strength, pain relief, ROM, and subjective outcomes are comparable for both groups. They found PRC to have a higher range of osteoarthritic change after surgery, although in most cases asymptomatic, but the FCA group showed more complications (10% more) overall due to nonunion, dorsal impingement, and complications related to hardware. No differences in the rate of conversion to TWA were observed. This is in line with our findings. Importantly, the different surgical methods are used in performing FCA. This may, in part, explain the different complications rate reported in FCA-treated patients ranging from 2 to 11%.
Mulford et al. noticed more complications and found nonunion to be higher in patients receiving a plate as opposed to K-wires and screws. This topic has long been contested and no standard technique exists.
Salzman et al. in a systematic review compared seven out of the 15 articles that were also included in our study.
The overall complication rate in the FCA was significantly higher and double that in the PRC group. In the present study, we specifically studied complications requiring reoperation, as many of the complications reported by Salzman et al., such as nonunion in the included studies, remained asymptomatic and could be treated conservatively. The included studies remain unclear on the distribution of the number of patients with advanced SLAC/SNAC grade III receiving PRC of FCA. No statistically significant differences were observed compared to pain severity and satisfaction, DASH score, or conversion rates to TWA, which is in line with our findings.
The outcomes of this study have to be interpreted keeping limitations in view. The majority of the included studies have a retrospective design with all of their inherent drawbacks, and are non-randomized, and include only a small number of patients. Statistical analysis is not performed in several instances, and SD or ranges are not mentioned precluding us from pooling the results. Only a minority of the studies measure the pre-operative status of the patients and compares that with the postoperative values. The lack of a baseline pre-operative value makes it particularly difficult to measure the degree of improvement postoperatively and compare it to other therapies. Several studies have shown the importance of preoperative clinical and functional measurements as a factor in estimating symptom relief after surgical treatment.
In addition, the SLAC and SNAC grading distribution within treatment groups remains unclear in most studies, making it difficult to make recommendations based on SLAC/SNAC grading. A difference in failure or nonunion rates may be attributable to different SLAC/SNAC grading or related to the surgical experience of the operator. FCA is a much more challenging operation compared to PRC. As shown in Figure 3, many studies do not report the number of surgeons executing this operation. There are only a handful of studies where one or two surgeons performed both operations. We also evaluated the risk of bias with the NIH tool. All studies, except two, were observational and vulnerable to bias. The risk of bias was high in almost all studies because of a poorly defined patient population and the lack of specified inclusion and exclusion criteria. No study could blind the examiners during outcome measurements. These limitations and differences could be attributed to the high heterogeneity that was noted among the studies for ROM, grip strength, rate of reoperation, and DASH scores.
Despite its limitations and the lack of multi-center randomized controlled trials, this study is the most up-to-date and comprehensive comparative systematic literature review and meta-analysis on comparing FCA and PRC in patients with degenerative SLAC and SNAC wrists. Compared to the most recent systematic review in 2015, this study contains eight more comparative studies and the largest number of patients treated with PRC or FCA. This study conducted a meta-analysis on the six most important postoperative outcome measures and is a significant update to the existing literature. Risk of bias assessment (lacking in previous studies) was also conducted to establish transparency and provide more insight into the included articles for comparison.
Based on our findings, differences between average treatment effects could not be shown and may be relatively small when evidence accumulates. Since present studies all focus on comparing mean differences between treatments, for future studies, it may be more important to focus on patient-specific factors that determine treatment outcome, preferably, in the future, allowing clinicians to understand and predict which patients will benefit more or less from specific interventions. Based on this study, the authors suggest PRC as the preferred choice over the FCA, if there is no midcarpal osteoarthritis, because of the relative simplicity and the lack of need for a rather long learning curve compared to FCA. In addition, PRC lacks early postoperative hardware-related complications and provides comparable long-term outcomes.
CRediT authorship contribution statement
Ali R. Ahmadi: Writing – review & editing, Data curation, Writing – review & editing. Liron S. Duraku: Conceptualization, Writing – review & editing. Mark J.W. van der Oest: Formal analysis, Writing – review & editing. Caroline A. Hundepool: Writing – review & editing. Ruud W. Selles: Writing – review & editing. J. Michiel Zuidam: Conceptualization, Writing – review & editing.
Declaration of Competing Interest
The authors wish to thank Wichor M. Bramer, PhD and Maarten F.M. Engel from the Erasmus MC Medical Library for developing and updating the search strategies. We also wish to thank the medical illustrator Ella Nitters, MSc, MA for providing high-quality illustrations.