Biomechanical Comparison of Suture-Button Suspensionplasty and LRTI for Basilar Thumb Arthritis

Management of a Traumatic Collapse of the First Carpometacarpal Joint After Trapeziectomy With Suture Suspensionplasty: A Case Report

Arthritis of the first carpometacarpal (CMC) joint is a common pathology hand surgeons encounter. Treatment begins with conservative measures, but when they fail, surgery is a viable option for providing relief to patients. The most widely used surgical technique is CMC arthroplasty with ligament reconstruction and tendon interposition (LRTI). However, more novel techniques such as trapeziectomy with suspensionplasty are gaining popularity. When surgical measures fail, it is important to identify the mechanism of failure and proper treatment options. There are multiple options for revision surgery at the surgeon's disposal, with no consensus on a superior technique. This case illustrates a patient with painful subsidence secondary to a traumatic collapse of the first CMC joint eight months status post suspensionplasty with trapeziectomy. After conservative measures failed to provide relief, it was decided that a surgical revision was appropriate. The surgeon chose to move forward with suture button suspensionplasty, as it has multiple advantages over LRTI. In the short-term follow-up after revision, the patient experienced improvements in pain and range of motion, along with radiographic evidence of proper alignment of the first metacarpal without subsidence. Regarding the treatment of a case such as this, the authors believe this case should serve as a reference that may be used by future physicians when deciding which surgical technique to employ for the revision of a traumatically collapsed first CMC joint after trapeziectomy with CMC joint suspensionplasty.

Biomechanical analysis of three techniques of suspensionplasty after trapeziectomy: a cadaveric study

The aim of the present cadaveric study was to assess resistance to first metacarpal subsidence of three techniques of suspensionplasty after trapeziectomy. In total, 18 forearms (mean age 60 years [range 20-89]) were used with six specimens per surgical technique: palmar oblique ligament reconstruction with tendon interposition (LRTI), abductor pollicis longus (APL) suspensionplasty, or suture suspensionplasty. There was no significant difference in mean trapezial space height after trapeziectomy and suspensionplasty compared to the preoperative trapezial height. However, after simulation of physiological lateral pinch, there was a significant (p < 0.05) difference in mean trapezial space height between the APL suspensionplasty and the suture suspensionplasty compared to the LRTI group. After axial loading, there was significantly greater metacarpal subsidence in the LRTI group compared to the APL and suture suspensionplasty groups but no statistically significant difference between the suture suspensionplasty and the APL suspensionplasty groups.Level of evidence: V.

First Carpometacarpal Joint Motion and Proximal Migration of the First Metacarpal After Tensioning of a Suture Device Suspensionplasty Compared With Trapeziectomy: A Biomechanical Cadaver Study

PURPOSE

The purpose of this cadaveric biomechanical experiment was to evaluate the effects of suture button suspensionplasty of the first carpometacarpal joint on thumb biomechanics and thumb position compared with an intact, arthritic specimen.

METHODS

Six tendons in 8 cadaver hands were loaded to simulate 6 activities of daily living and passively moved through a circumduction motion. Proximal migration of the base of the first metacarpal was measured using optical motion sensors in the intact hand, after trapeziectomy, and following insertion of a suture button suspensionplasty with nominal tightening (approximately 4.5 N) and with firm tightening (approximately 44.5 N).

RESULTS

Removal of the trapezium caused a significant increase in the proximal migration of the first metacarpal during a simulated jar grasp, opposition, flexion, extension, and abduction (average, 9.5 mm) compared with its location with the thumb in the intact, neutral position (average, 3.8 mm). Firm tightening of the tightrope caused a near elimination of the proximal migration of the first metacarpal (average, 0.7 mm). In all 6 static loading cases with the trapezium removed, firm tightening caused a significantly smaller migration than in the absence of tightening.

CONCLUSIONS

This biomechanical cadaver study supports the hypothesis that trapeziectomy results in proximal migration of the first metacarpal. Suture suspensionplasty mitigates against this migration while maintaining normal motion of the first metacarpal compared with the intact state. Firm tightening of the suture does not adversely affect the first metacarpal's mobility and further decreases proximal migration. However, firm tightening may cause impingement between the first and second metacarpals.

CLINICAL RELEVANCE

Suture button suspensionplasty can be used in addition to trapeziectomy in the treatment of basal joint arthritis, and may diminish the need for ligament reconstruction or temporary K-wire insertion.

Systematic Comparison of Ligament Reconstruction With Tendon Interposition and Suture-Button Suspensionplasty for Trapeziometacarpal Osteoarthritis

Ligament reconstruction tendon interposition (LRTI) and suture-button suspensionplasty (SBS) are both common treatment options for trapeziometacarpal osteoarthritis. The primary purpose of this systematic review was to compare the subjective improvement in patient-reported outcomes in regard to disability for patients undergoing LRTI and SBS for trapeziometacarpal osteoarthritis. A secondary purpose was to compare the subjective improvement, objective outcome scores, and complication rates following both procedures. We performed a systematic review using PubMed, Scopus, and Embase to compare the clinical outcomes of LRTI and SBS. Inclusion criteria were level I-IV evidence articles reporting postoperative Disabilities of the Arm, Shoulder, and Hand (DASH) or QuickDASH scores. Study methodological quality, risk of bias, and recommendation strength were assessed. This systematic review included 31 studies for final analysis with 1289 thumbs undergoing LRTI (25 studies) and 113 thumbs undergoing SBS (6 studies). Both procedures demonstrated similar improvement in DASH and/or QuickDASH scores, while key pinch and grip strength inconsistently improved following both procedures. Complication rate was similar between the 2 procedures; LRTI 12% and SBS 13%. Although both LRTI and SBS seem to provide improved short-term patient-reported functional improvement and objective strength, there was significant heterogeneity within the included studies, and those studies discussing SBS were of lower quality evidence than those of LRTI. Thus, to truly delineate whether a difference exists between these 2 techniques for the treatment of first carpometacarpal joint arthritis, larger prospectively designed studies of high-quality evidence are necessary.

Transosseous Cannula Suture Suspensionplasty for Thumb Basal Joint Arthritis: A Novel Technique

The suture button (SB) suspension technique has become popular in the treatment of thumb basal joint arthritis, as it works as an internal mean for metacarpal stabilization, demonstrating good results with improvement in function and strength. The aim of our study is to describe a new transosseous suture suspensionplasty technique using a simple Ethibond #2 suture as a substitute for the suture button and to report the postoperative clinical outcomes. In this study, we included a total of 14 patients with 2 years follow-up. We evaluated patients with the use of the Disabilities of the Arm, Shoulder and Hand questionnaire, the Visual Analog Scale, the Kapandji test, and the key pinch strength. Patients treated with transosseous suture suspensionplasty demonstrated clinical improvement at an average follow-up of 24 months. No complications were noted immediately after the procedure or during the 2-year follow-up period.

A 15-Year Review of Clinical Practice Patterns and Evidence-Based Medicine in Carpometacarpal Joint Arthroplasty

BACKGROUND

The purpose of this study was to help understand national practice patterns in carpometacarpal (CMC) arthroplasty and how they have evolved with evidence-based recommendations over the past 15 years.

METHODS

The American Board of Plastic Surgery (ABPS) started collecting practice data on primary CMC joint arthroplasty in 2006 as a portion of its continuous certification (CC) process. Data on primary CMC arthroplasty from May 2006 through December 2013 were reviewed and compared to those from January 2014 to March 2020. National practice trends observed in these data were evaluated. Comprehensive evidence-based medicine reviews published in 2008, 2011, 2013, and 2017 were reviewed alongside the CC data.

RESULTS

In all, 570 primary CMC joint arthroplasty cases were included from May 2006 to March 2020. The average age at the time of repair was 62 years and the patient population was predominantly female (79%). Most cases were done under general anesthesia (69%), and there was an increase in the use of regional anesthesia with nerve block when our 2 cohorts were compared (27% vs 37%; P = .020). A trapezium excision with flexor carpi radialis tendon ligament reconstruction was the most popular technique (72%) and an increase in the use of simple trapeziectomy was observed (6% vs 14%; P = .001). One-third of patients did not receive any form of deep vein thrombosis prophylaxis.

CONCLUSIONS

The ABPS CC data provide a databank that allows for direct observation of national practice trends and sheds light on potential avenues for improvement in patient care.

Natural History of Metacarpal Subsidence following Trapeziectomy and Its Relationship to Clinical Outcomes

METHODS

An institutional review board-approved retrospective review of patients who underwent trapeziectomy and ligament reconstruction and tendon interposition (LRTI) was conducted. Patient demographics, visual analogue scale pain scores, grip strength, pinch strengths, and radial and palmar abduction were collected. The trapezial space ratio (TSR) was measured by the scaphometacarpal distance divided by the length of the capitate. Subsidence [(postoperative TSR - preoperative TSR)/preoperative TSR] was measured and classified as severe (≥70%) or mild to moderate (<70%). Median rate of subsidence increase was calculated. Conolly-Rath scores were used to evaluate the proportion of good outcomes in each group.

RESULTS

A total of 141 trapeziectomies with LRTI were included. Subsidence increased 6.7% (5.4% to 23.0%) per week before 16 weeks and 0.3% (0.1% to 0.8%) per week thereafter. Visual analogue scale pain scores were not significantly different between patients with severe or mild to moderate subsidence ( P = 0.25) 16 weeks after thumb mobilization. The proportion of good outcomes was comparable between the two groups ( P = 0.12). There was no correlation between subsidence and pain (ρ = -0.20; P = 0.24), grip (ρ = -0.02; P = 0.93), key (ρ = -0.13; P = 0.62), tripod (ρ = 0.16; P = 0.71), or index tip pinch strengths (ρ = -0.28; P = 0.43) or radial (ρ = -0.03; P = 0.92) or palmar (ρ = -0.15; P = 0.61) abduction.

CONCLUSIONS

Subsidence occurs in all patients after trapeziectomy and LRTI, stabilizing 16 weeks after mobilization. Degree of subsidence does not correlate with postoperative outcomes.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Risk, II.

"Suspensionplasty for Revision Thumb Carpometacarpal Osteoarthritis Surgery: Comparing Suture Button Suspensionplasty to Ligament Reconstruction and Tendon Interposition."

Several surgical procedures have been described for the treatment of thumb carpometacarpal (CMC) osteoarthritis (OA), including suture button suspensionplasty (SBS) and ligament reconstruction and tendon interposition (LRTI). To date, no one procedure has demonstrated clinical superiority. SBS has achieved favorable outcomes at five years in primary cases, but has not been validated in revision surgery. This study evaluated SBS for revision of failed thumb CMC OA surgery and compared these outcomes to revision using LRTI. A retrospective chart review was performed to identify patients who underwent suspensionplasty with SBS or LRTI after failure of previous thumb CMC OA surgery since 2010. Eighteen patients were included, nine undergoing revision with SBS and nine undergoing revision with LRTI. Eighteen patients had mean final follow-up of 35 months. There were two complications in the LRTI group, none in the SBS group. No patients required additional surgery. The SBS group had an average visual analog scale (VAS) pain score improvement of 2.9, compared to 2.4 in the LRTI group. Average final QuickDASH was 15.1 in the SBS group, compared to 22.6 in the LRTI group. Mean operative time of 86.3 minutes in the SBS group was significantly shorter than the 121 minute mean in the LRTI group. SBS is an effective treatment option for revision of previous thumb CMC OA surgery, with outcomes comparable to revision using LRTI, and the added benefit of shorter operative times and early mobilization.

Biomechanical Analysis of Abductor Pollicis Longus Lasso Suspensionplasty for Trapeziectomy

PURPOSE

Multiple methods of ligament reconstruction and tendon interposition (LRTI) or suspension have been described to prevent first metacarpal subsidence following trapeziectomy. An abductor pollicis longus (APL) lasso is a newly described technique of suspensionplasty, which aims to obviate concerns regarding previously described methods. The purpose of this study was to compare subsidence between the APL lasso and 2 other common methods, APL sling and flexor carpi radialis LRTI, after trapeziectomy in cadaveric forearms.

METHODS

Ten cadaveric forearms were prepared on a custom-made plinth to recreate pinch grip upon the loading of previously identified muscles. A sequence of procedures was performed, with radiographs taken after each to assess the subsidence.

RESULTS

The APL lasso was superior to simple trapeziectomy and flexor carpi radialis LRTI in preventing subsidence.

CONCLUSIONS

The APL lasso was superior to simple trapeziectomy and flexor carpi radialis LRTI in preventing subsidence, and it may be a viable alternative when considering suspension methods after trapeziectomy.

CLINICAL RELEVANCE

The APL lasso may be considered when trying to prevent subsidence after trapeziectomy.

Indications for Ligament Reconstruction and Suspensionplasty in Carpometacarpal Arthroplasty

The trapeziometacarpal joint is the site that most commonly develops arthritis in the hand. Although optimal treatment requires careful consideration of history, physical examination, radiographs, and functional goals, many patients ultimately undergo surgical intervention. Several described techniques and approaches are highlighted in this article, especially pertaining to carpometacarpal arthroplasty with ligament reconstruction and tendon interposition. The rationale, benefit, and evidence for each approach are discussed and the author's preferred technique is described.

A Case of Carpal Tunnel Syndrome Resulting from Interference Screw Malposition after LRTI

Many approaches to CMC arthroplasty have been described for treatment of advanced arthritis, yet there is no consensus on the “best” operation. Implantable hardware is increasingly utilized for metacarpal suspension, but few hardware-mediated complications have been documented. Here we present the case of a 69-year-old man with insidious-onset median neuropathy following ligament reconstruction and tendon interposition for CMC arthritis, utilizing interference screw fixation. After surgery, the patient developed median neuropathy, and his physical examination and MRI demonstrated a mass in the volar wrist. Operative exploration revealed an interference screw that was lodged immediately volar to the transverse carpal ligament, causing median nerve compression. Median neurolysis and screw removal led to symptom resolution. Carpal tunnel syndrome is an unreported complication of interference screw use during thumb CMC arthroplasty, and should be considered in patients with postoperative median neuropathy following ligament reconstruction and tendon interposition.

Trapeziometacarpal joint loading during key pinch grip: A cadaver study

To our knowledge, no study has directly measured the loads in the trapeziometacarpal joint during an isometric key pinch. The aim of this study was to measure the load acting on the trapeziometacarpal joint for increasingly greater key pinch forces (0.5 kg-1.5 kg). We performed a cadaver study using 10 fresh-frozen, unembalmed adult forearms and hands (5 right and 5 left). Thumb pinch was simulated by loading the main actuator tendons involved in the key pinch grip (i.e., adductor pollicis, flexor pollicis longus, extensor pollicis longus, extensor pollicis brevis and abductor pollicis longus tendons). Measurements were made inside the joint using a force-sensing resistor sensor (Tekscan® FlexiForce™ force sensor). All specimens were tested twice in a row in the same condition. The median load values recorded in the trapeziometacarpal joint were 1.9 kg (IQR 2.2-1.5), 3 kg (IQR 3.4-2.7) and 4.1 kg (IQR 4.4-3.9) during 0.5 kg, 1 kg, and 1.5 kg key pinch, respectively. For each specimen, similar load values were observed during both loading trials. Our findings indicate that the loads measured directly in the trapeziometacarpal joint during a simple key pinch are materially lower than those estimated in biomechanical models of the thumb (generally greater than 10 kg for 1 kg of applied force) probably due to intersubject variability. This pilot study will serve as a basis for further studies, for example, comparing biomechanical thumb models and experimental measurements under the same set-up conditions.

Comparison of simulated key pinch after three surgical procedures for trapeziometacarpal osteoarthritis: a cadaver study

We performed a cadaver study using 18 fresh-frozen adult forearms and hands to compare the tendon loads required to generate progressively greater key pinch (0.5 kg to 2 kg) after three different surgical procedures to treat trapeziometacarpal osteoarthritis: isolated trapeziectomy, trapeziectomy followed by ligament reconstruction with tendon interposition and total joint arthroplasty using a Touch® implant. Thumb pinch was simulated by loading the main actuator tendons involved in the key pinch. Six specimens were randomly assigned to each of the three surgical procedure groups. Measurements were made before and after the joint surgery. Specimens that underwent trapeziectomy with or without ligament reconstruction with tendon interposition required significantly higher tendon loads than those with the implant to achieve the same pinch force. There was no significant difference between the isolated trapeziectomy and ligament reconstruction groups. Using the implant resulted in similar median tendon loads compared with those of the intact sample. Total joint arthroplasty with a Touch® prosthesis may yield a superior biomechanical profile in which the tendon loads needed to achieve a certain key pinch force are lower and better distributed between the actuator muscles compared with trapeziectomy with or without ligament reconstruction.

Trapeziectomy with suture-button suspensionplasty versus ligament reconstruction and tendon interposition: a randomized controlled trial

The purpose of the present study was to compare the results of patients operated with trapeziectomy and ligament reconstruction and tendon interposition (LRTI) using flexor carpi radialis tendon versus trapeziectomy followed by suspension of the first metacarpal to the second metacarpal using a Mini TightRope® suture button (suture button suspension: SBS). A single-center prospective randomized controlled trial was performed, comparing 37 patients with SBS and 39 with LRTI. All surgeries were performed by the same fellowship-trained hand surgeon. Patients were assessed by an independent observer at 40 months' follow-up. Pre- and postoperative strength, trapezial space ratio (TSR), range of motion, QuickDASH and visual analogue pain score were recorded. Both procedures improved functional parameters of pain, key strength, tip strength and grip strength while maintaining range of motion, without significant differences. In the SBS group, TSR decreased by 17%, compared to 28% in the LRTI group. The mean operative time was shorter in SBS (63 vs 91 minutes; p < 0.0001), as was immobilization time (2 vs 6 weeks; p < 0.0001), and patients resumed normal activity sooner (10 vs 12 week; p = 0.0138) and required less physical therapy (19.3 vs 13.1 weeks; p < 0.0001). We believe that our results are related to the hypothesis suggested by biomechanical studies that revealed better initial load bearing profile and maintenance of trapezial space following serial loading in cadaver models.

Technical trick in suture-button suspensionplasty for the treatment of thumb carpometacarpal arthritis

Suture-button suspensionplasty has been popularized in the treatment of thumb carpometacarpal (CMC) arthritis in recent years. The surgical technique of this method was well defined previously. The most challenging and important part of this technique is the tensioning of the suture-button system to preserve first metacarpal height after trapeziectomy. In present study, we would like to present a technical trick about adjusting the tension while performing suspensionplasty using suture-button device in thumb CMC joint osteoarthritis. In the original technique, trapeziectomy is performed prior to fixation and tensioning of suture-button system. However, it is quite difficult to recreate the original trapezial space, since first metacarpal subsides after trapeziectomy. The trick in our technique is that trapezium remains in its anatomic position up to the end of the operation. Thus, we do not need to make effort to adjust the thumb ray height and use fluoroscopic imaging to ensure its position. In conclusion, we believe that our technique simplifies the most challenging part of the operation, shortens the operation time, preserves the original first ray height and diminishes the exposure of ionizing radiation as it reduces the need for fluoroscopy.

Mini TightRope® suture button indications for thumb basal joint arthritis

Our aim was to explore the different indications of the Mini TightRope® suture button whether during first-line treatment or secondary surgery of thumb carpometacarpal osteoarthritis (OA). The indications for this new device are presented and discussed based on our own small case series and published data. Twenty-one patients treated with the Mini TightRope® were included in a prospective study. One of them was operated on both sides. Fourteen devices were used in first intention for Eaton stage IV OA; the patients underwent trapeziectomy and suture button suspensioplasty only. Four cases consisted of revision surgery for painful proximalization of the first metacarpal after trapeziectomy and ligamentoplasty. Four cases consisted of secondary surgery after trapeziectomy and implant interposition (two silicone implants and two pyrocarbon implants). We captured the demographic data, follow-up time, pain level, pinch strength before and after surgery, range of motion, metacarpal subsidence, and postoperative complications. The average age of the patients was 60 years. There were 19 women and 2 men. The average follow-up time was 2.5 years (1-4). The average pain level, according to a visual analog scale (1-10) was 3.5 (2-5) preoperatively and 2 (1-4) postoperatively at rest and 7 (6-8) preoperatively and 4 (3-6) postoperatively with maximum load. The mean Kapandji score was 9 (7-10) and the retropulsion score was 3 (1-4). The average key pinch and tip pinch strengths were 80% and 78% of the contralateral side at the final follow-up. The trapeziectomy-suspensioplasty group had greater average trapezial space height compared to the revision surgery group (7.0 mm vs. 4.5 mm). There are several indications for the Mini TightRope® device in the treatment of severe thumb carpometacarpal OA: first metacarpal suspension during open or arthroscopic total or partial trapeziectomy and secondary surgery after failure of trapeziectomy with or without implant interposition. The advantage of this new device, which suspends the first metacarpal off the second metacarpal, is the very short immobilization period contrary to other suspensioplasty procedures.

Arthroscopic Trapeziectomy and Suture Button Suspensionplasty: A Review of the Literature and Description of the "Three-Step Arthroscopic Trapeziectomy Technique"

In the last two decades, surgeons have rapidly developed arthroscopic techniques to treat basal joint osteoarthritis. Such techniques spare the joint capsule and ligaments, allow more accurate staging of cartilage degeneration to determine the most appropriate treatment, and decrease the risk of injury to the radial artery and superficial branch of the radial nerve. Arthroscopic resection arthroplasty of the trapezium can be performed as either partial or complete trapeziectomy. Many papers have described partial trapeziectomy but few have discussed complete trapeziectomy. Suture button implants avoid the drawbacks of temporary fixation using Kirschner wire, as well as the drawbacks of ligament reconstruction, which necessitates the sacrifice of a tendon and involves both wide exposure and scar tissue. This paper aimed to review the published data on the arthroscopic treatment of basal thumb osteoarthritis, with a special focus on stabilization using suture button suspensionplasty, and to present a technique that structures this procedure into three steps, allowing it to be performed in an easier, more organized, and faster way.

Suture Button Suspensionplasty in the Treatment of Carpometacarpal Arthritis: A Retrospective Analysis of One Surgeon’s Experience Over 9 Years

Purpose

Trapeziectomy with suture button suspensionplasty (SBS) to treat thumb carpometacarpal (CMC) arthritis has been proposed as an alternative to ligament reconstruction tendon interposition. There have been limited large-scale or long-term reports regarding SBS outcomes. Single-surgeon intermediate follow-up is reported.

Methods

We conducted a retrospective review of patients undergoing SBS procedures by a single surgeon. Implant manufacturer and postoperative immobilization protocol were recorded. Surgical outcomes, complications, and revision procedures were identified. Postoperative Disabilities of the Arm, Shoulder, and Hand scores were collected.

Results

A total of 242 SBS surgeries were included, involving 215 patients, average age 64.82 years (range, 42–86 years). Average follow-up was 35 ± 25 months. In all, 183 Arthrex and 59 Stryker systems were used, 42 of which were immobilized for 6 weeks after surgery and 200 of which were mobilized at 2 weeks afterward. Postoperative Disabilities of the Arm, Shoulder, and Hand surveys were completed by 122 patients (57%), with an average score of 12. No scaphometacarpal abutment was reported. Thirteen complications were reported (5%), 7 of which were implant-associated (3%) and 6 of which were not (2%). Implant-associated complications consisted of 3 suture button pull-outs, 2 thumb–index metacarpal abutments, one suture tail irritation, and one index metacarpal fracture. Operative revision was required in 4 of 7 implant-associated cases and 5 of 6 non–implant associated cases. No suture button pull-outs required revision surgery.

Conclusions

Results for a large series of SBS for CMC arthroplasty with intermediate follow-up revealed excellent clinical outcomes and low complication rates.

Clinical relevance

Suture button suspensionplasty as an alternative to ligament reconstruction tendon interposition may be a viable option for treating thumb CMC arthritis. In addition, a technique to manage thumb–index metacarpal abutment is described.

Four-Strand Versus 2-Strand Suture-Button Constructs in First Carpometacarpal Arthroplasty: A Biomechanical Study

Background: Suture-button fixation is an alternative to no fixation, first metacarpal distraction techniques, or Kirschner wire fixation after trapeziectomy in treatment of first carpometacarpal (CMC) arthritis. A 4-strand suture-button construct requires a 2.7-mm tunnel, whereas a 2-strand construct requires a 1.1-mm tunnel, potentially decreasing the risk of metacarpal fracture. We compared stability and failure criteria of 4-strand versus 2-strand construct in a biomechanical model of first CMC joint arthroplasty. Methods: Ten fresh-frozen matched pairs of human cadaveric hands were randomized to receive a 4-strand or 2-strand suture-button device. Trapeziectomy and fluoroscopic measurement of the fixed posttrapeziectomy space was performed before and after cycling 1000 times at 0.2 Hz in a custom loading device. The constructs were loaded to failure and failure mechanism was noted. Results: There was no significant difference between the groups in unfixed posttrapeziectomy, fixed precyclic loading, or postcyclic loading height. No difference in pinch pressure was found in any group. No difference in load to failure was observed. The 4-strand device failed through the first ray in 8 of 11 specimens, and the suture of the 2-strand device failed in 5 of 9 specimens. Conclusions: The 4-strand and 2-strand suture-button constructs provide comparable biomechanical stability for first CMC arthroplasty. If construct stability is similar between these procedures, the smaller tunnel used with the 2-strand construct may offer an advantage.

Benefits of Additional Procedures for Metacarpophalangeal Hyperextension on Simple Trapeziectomy in Thumb Basal Osteoarthritis: A Biomechanical Cadaver Study

Background: Patients with advanced osteoarthritis of the first carpometacarpal joint (CMC-1) may develop hyperextension of the first metacarpophalangeal joint (MCP-1). No clear clinical benefice has been reported consecutively to the surgical treatment of the MCP-hyperextension combined to a trapeziectomy. The reason of the missing benefit may be due to changes in the thumb position impairing the thumb stability secondary to the surgical procedures. We assessed changes in the transmission of forces at the thumb's end phalanx following a trapeziectomy combined with the surgical adjustment of the hyperextension of the MCP-1-joint in a biomechanical investigation using cadavers. Methods: The thumb muscles were loaded with nylon cables connected to a tension meter in 8 forearm cadavers. A 6-axis force sensor assessed the termino-lateral key-pinch orthogonal strength vectors at the level of the thumb distal phalanx prior to any surgery, and following a simple trapeziectomy, a trapeziectomy combined to a MCP-1-capsulodesis and the transfer of the extensor pollicis brevis over the metacarpal-1 head, or to an MCP-1-arthrodesis. Results: Combination of the trapeziectomy with the MCP-1- joint palmar capsulodesis and EPB-transfer or with a MCP-arthrodesis in neutral pronation-supination resulted in a significant shift of the thumb in pronation-abduction with respect to the preoperative assessment. The lowest shift was achieved when performing the arthrodesis in 20° supination or by overloading of the adductor pollicis. Conclusions: Combining the trapeziectomy with surgeries addressing the MCP-1-joint hyperextension induced a shift of the thumb in pronation-abduction that could impair the key-pinch stability. When considering additional procedures for MCP-1-joint hyperextension deformities, it should be recommended to fix the EPB-tendon on the radial aspect of the metacarpal head if a tendon transfer is considered, otherwise the MCP joint arthrodesis should be performed in supinated position, in order to achieve lateral key-pinch stability.