Dorsal Subluxation of the First Metacarpal During Thumb Flexion is an Indicator of Carpometacarpal Osteoarthritis Progression

BACKGROUND

Measurable changes in patients with progression of thumb carpometacarpal (CMC) osteoarthritis (OA) include joint space narrowing, osteophyte formation, subluxation, and adjacent-tissue changes. Subluxation, an indication of mechanical instability, is postulated as an early biomechanical indicator of progressing CMC OA. Various radiographic views and hand postures have been proposed to best assess CMC subluxation, but 3D measurements derived from CT images serve as the optimal metric. However, we do not know which thumb pose yields subluxation that most indicates OA progression.

QUESTIONS/PURPOSES

Using osteophyte volume as a quantitative measure of OA progression, we asked: (1) Does dorsal subluxation vary by thumb pose, time, and disease severity in patients with thumb CMC OA? (2) In which thumb pose(s) does dorsal subluxation most differentiate patients with stable CMC OA from those with progressing CMC OA? (3) In those poses, what values of dorsal subluxation indicate a high likelihood of CMC OA progression?

METHODS

Between 2011 and 2014, 743 patients were seen at our institutions for trapeziometacarpal pain. We considered individuals who were between the ages of 45 and 75 years, had tenderness to palpation or a positive grind test result, and had modified Eaton Stage 0 or 1 radiographic thumb CMC OA as potentially eligible for enrollment. Based on these criteria, 109 patients were eligible. Of the eligible patients, 19 were excluded because of a lack of interest in study participation, and another four were lost before the minimum study follow-up or had incomplete datasets, leaving 86 (43 female patients with a mean age of 53 ± 6 years and 43 male patients with a mean age of 60 ± 7 years) patients for analysis. Twenty-five asymptomatic participants (controls) aged 45 to 75 years were also prospectively recruited to participate in this study. Inclusion criteria for controls included an absence of thumb pain and no evidence of CMC OA during clinical examination. Of the 25 recruited controls, three were lost to follow-up, leaving 22 for analysis (13 female patients with a mean age of 55 ± 7 years and nine male patients with a mean age of 58 ± 9 years). Over the 6-year study period, CT images were acquired of patients and controls in 11 thumb poses: neutral, adduction, abduction, flexion, extension, grasp, jar, pinch, grasp loaded, jar loaded, and pinch loaded. CT images were acquired at enrollment (Year 0) and Years 1.5, 3, 4.5, and 6 for patients and at Years 0 and 6 for controls. From the CT images, bone models of the first metacarpal (MC1) and trapezium were segmented, and coordinate systems were calculated from their CMC articular surfaces. The volar-dorsal location of the MC1 relative to the trapezium was computed and normalized for bone size. Patients were categorized into stable OA and progressing OA subgroups based on trapezial osteophyte volume. MC1 volar-dorsal location was analyzed by thumb pose, time, and disease severity using linear mixed-effects models. Data are reported as the mean and 95% confidence interval. Differences in volar-dorsal location at enrollment and rate of migration during the study were analyzed for each thumb pose by group (control, stable OA, and progressing OA). A receiver operating characteristic curve analysis of MC1 location was used to identify thumb poses that differentiated patients whose OA was stable from those whose OA was progressing. The Youden J statistic was used to determine optimized cutoff values of subluxation from those poses to be tested as indicators of OA progression. Sensitivity, specificity, negative predictive values, and positive predictive values were calculated to assess the performance of pose-specific cutoff values of MC1 locations as indicators of progressing OA.

RESULTS

In flexion, the MC1 locations were volar to the joint center in patients with stable OA (mean -6.2% [95% CI -8.8% to -3.6%]) and controls (mean -6.1% [95% CI -8.9% to -3.2%]), while patients with progressing OA exhibited dorsal subluxation (mean 5.0% [95% CI 1.3% to 8.6%]; p < 0.001). The pose associated with the most rapid MC1 dorsal subluxation in the progressing OA group was thumb flexion (mean 3.2% [95% CI 2.5% to 3.9%] increase per year). In contrast, the MC1 migrated dorsally much slower in the stable OA group (p < 0.001), at only a mean of 0.1% (95% CI -0.4% to 0.6%) per year. A cutoff value of 1.5% for the volar MC1 position during flexion at enrollment (C-statistic: 0.70) was a moderate indicator of OA progression, with a high positive predictive value (0.80) but low negative predictive value (0.54). Positive and negative predictive values of subluxation rate in flexion (2.1% per year) were high (0.81 and 0.81, respectively). The metric that most indicated a high likelihood of OA progression (sensitivity 0.96, negative predictive value 0.89) was a dual cutoff that combined the subluxation rate in flexion (2.1% per year) with that of loaded pinch (1.2% per year).

CONCLUSION

In the thumb flexion pose, only the progressing OA group exhibited MC1 dorsal subluxation. The MC1 location cutoff value for progression in flexion was 1.5% volar to the trapezium , which suggests that dorsal subluxation of any amount in this pose indicates a high likelihood of thumb CMC OA progression. However, volar MC1 location in flexion alone was not sufficient to rule out progression. The availability of longitudinal data improved our ability to identify patients whose disease will likely remain stable. In patients whose MC1 location during flexion changed < 2.1% per year and whose MC1 location during pinch loading changed < 1.2% per year, the confidence that their disease would remain stable throughout the 6-year study period was very high. These cutoff rates were a lower limit, and any patients whose dorsal subluxation advanced faster than 2% to 1% per year in their respective hand poses, were highly likely to experience progressive disease.

CLINICAL RELEVANCE

Our findings suggest that in patients with early signs of CMC OA, nonoperative interventions aimed to reduce further dorsal subluxation or operative treatments that spare the trapezium and limit subluxation may be effective. It remains to be determined whether our subluxation metrics can be rigorously computed from more widely available technologies, such as plain radiography or ultrasound.

Bone morphological changes of the trapezium and first metacarpal with early thumb osteoarthritis progression

BACKGROUND

Thumb carpometacarpal osteoarthritis is characterized by osteophyte growth and changes in the curvature of the articular surfaces of the trapezium and first metacarpal. The aim of this longitudinal study was to quantify in-vivo bone morphology changes with osteoarthritis progression.

METHODS

The study analyzed an observational dataset of 86 subjects with early thumb osteoarthritis and 22 age-matched asymptomatic controls. CT scans of subjects' affected hands were acquired at enrollment (year 0), and at 1.5, 3, 4.5, and 6-year follow-up visits. Osteoarthritic subjects were classified into stable and progressive groups, as defined by osteophyte volume and the rate of osteophyte growth. Trapezium height, width, and volar facet recession, along with first metacarpal volar beak recession and recession angle, were quantified.

FINDINGS

Mean trapezium width increased 12% over six years in the progressive osteoarthritis group. Trapezium volar recession of the progressive osteoarthritis group was significantly greater than stable at enrollment (P < 0.0001) and year 6 (P < 0.0001). The first metacarpal volar beak of the progressive osteoarthritis group recessed significantly faster than stable (P = 0.0004) and control (P = 0.0003). In year 6, volar beak surfaces in subjects with progressive osteoarthritis were flatter with reduced curvature, measuring -8.7 ± 4.0 degrees, compared to the stable osteoarthritis (P < 0.0001) and control groups (P = 0.0003), which maintained nominal curvatures, measuring 0.7 ± 2.5 and 0.2 ± 3.2 degrees, respectively.

INTERPRETATION

Our results demonstrate significant recession and reduction in the angle of the first metacarpal volar beak in progressive osteoarthritis. Flattening of the first metacarpal volar beak may have important associations with carpometacarpal joint contact and loading migrations, further propagating osteophyte formation and bony remodeling. This work highlights the volar beak of the first metacarpal as a region of morphology change with disease.

Implant Charge Differences Between Distal Radius Fixation Constructs (CPT 25607, 25608, and 25609)

BACKGROUND

Implants are a significant contributor to health care costs. We hypothesized that extra-articular fracture patterns would have a lower implant charge than intra-articular fractures and aimed to determine risk factors for increased cost.

METHODS

In total, 163 patients undergoing outpatient distal radius fracture fixation at 2 hospitals were retrospectively reviewed stratified by Current Procedural Terminology codes. Implants and associated charges were noted, as were sex, age, insurance status, surgeon specialty, and location. Bivariate and multivariable regression were used to determine associations.

RESULTS

Total implant charges were significantly lower for 25607 (extraarticular, $3,348) than 25608 (2-part intraarticular, $3,859) and 25609 (3+ part intraarticular, $3,991). In addition, intra-articular fractures had higher charges for distal screws/pegs and bone graft. Charge was lower when surgery was performed at a trauma center. There was no charge difference associated with insurance status, age, sex, hand surgery specialty, or fellow status. Substantial intersurgeon variation existed in all fracture types.

CONCLUSION

Distal radius fractures may represent a good model for examining implant costs. Extra-articular fractures had lower implant charges than intra-articular fractures. These data may be used to help construct pricing for distal radius fracture bundles and potential cost savings.

Evaluation of the PROMIS Upper Extremity Against Validated Patient-Reported Outcomes in Patients With Early Carpometacarpal Osteoarthritis

PURPOSE

Internal consistency, construct, and criterion validity of the Patient-Reported Outcomes Measurement Information System (PROMIS) upper extremity (UE) v1.2 were evaluated in patients with early-stage carpometacarpal (CMC) osteoarthritis (OA). We hypothesized that in patients with early CMC OA, PROMIS UE scores would: (1) be lower than those in asymptomatic controls; (2) correlate with established patient-reported outcomes; (3) correlate with pinch and grip strengths; and (4) not correlate with radiographic disease progression.

METHODS

Patients with early CMC OA (modified Eaton stage 0 or 1) and matched asymptomatic control patients completed the PROMIS UE, Australian and Canadian Osteoarthritis Hand Index, and Patient-Rated Wrist-Hand Evaluation at 2 time points. The PROMIS UE's internal consistency was evaluated by Cronbach's alpha, construct validity by Spearman correlation coefficients among the patient-reported outcome measures, and criterion validity using measures of strength. A floor or ceiling effect was indicated if more than 15% of patients achieved the lowest or highest possible score.

RESULTS

The PROMIS UE had high internal consistency. Patients with early CMC OA had a lower score than healthy controls (average, 42 vs 54, respectively). We observed moderate to high correlations between the PROMIS UEv1.2, Australian and Canadian Osteoarthritis Hand Index, and Patient-Rated Wrist-Hand Evaluation and good criterion validity when compared to key pinch and grip strengths. The PROMIS UE did not correlate to radiographic disease severity.

CONCLUSIONS

The PROMIS UE had a high correlation with Australian and Canadian Osteoarthritis Hand Index and a moderate correlation with Patient-Rated Wrist-Hand Evaluation. The PROMIS UE had high internal consistency and good criterion validity.

CLINICAL RELEVANCE

The PROMIS UE is a valid assessment for disability in patients with early CMC OA and can serve as a clinical adjunct to an outcome assessment.

The Association of AUSCAN and PRWHE Patient-reported Outcome Measures With Radiographic Progression of Early Thumb Carpometacarpal Arthritis at 36-Month Follow-up Is Limited to Subtle Changes in the Pain Subscale

BACKGROUND

There is a paucity of literature that examines how patient-reported outcomes correspond to early radiographic progression of thumb carpometacarpal (CMC) osteoarthritis (OA). This study examines how Australian/Canadian Osteoarthritis Hand Index (AUSCAN) and Patient-Rated Hand and Wrist Evaluation (PRWHE) scores change over 36 months in subjects with early CMC OA.

METHODS

Ninety-one subjects with symptomatic early thumb CMC OA were enrolled. Differences in AUSCAN and PRWHE scores were measured between subjects at baseline and at 18-month follow-up, and between the subjects at baseline and at 36-month follow-up. Radiographic progression was defined as an increase in modified Eaton Stage. Differences in AUSCAN and PRWHE scores were compared between these 2 groups in order to determine if radiographic progression was associated with a greater change in AUSCAN and PRWHE at 18- and 36-month follow-up.

RESULTS

At 18- and 36-month follow-up visits, there were no significant differences in AUSCAN or PRWHE compared to baseline. Multivariable logistic regression analysis did not reveal any significant differences between subjects with radiographic progression to subjects without radiographic progression at 18-month follow-up. At 36-month follow-up, this analysis did demonstrate that subjects with evidence of radiographic progression had a significant increase in the PRWHE pain subscale.

CONCLUSION

AUSCAN and PRWHE scores were not found to significantly progress at 18-month and 36-month follow-up. However, when comparing the subset of subjects with and without radiographic OA, subjects with early CMC OA who had 1 stage of radiographic progression were found to have a significantly higher intensity of pain on the PRWHE pain subscale at 36-month follow-up.

Rates of and Risk Factors for Trigger Finger after Open Carpal Tunnel Release

Background  We have anecdotally noticed a higher rate of trigger fingers (TFs) developing in patients who have undergone carpal tunnel release (CTR). Questions/Objective  Is the rate of TFs after CTR greater compared to the nonoperative hand? Is the thumb more commonly involved postoperatively compared with spontaneous TFs? Do particular associated comorbidities increase this risk? Patients and Methods  We queried our institutional database for patients who had undergone open CTR during a 2-year period and recorded the development of an ipsilateral TF after a CTR or a contralateral TF in the nonoperative hand. Patient demographics, comorbidities, concurrent initial procedures, time to diagnosis, and finger involvement were recorded. Results  A total of 435 patients underwent 556 CTRs during this period. Furthermore, 46 ipsilateral TFs developed in 38 of 556 cases (6.83%) at an average of 228.1 ± 195.7 days after surgery. The thumb was most commonly involved (37.0%) followed by the ring finger (28.3%). The incidence rate of TF in the nonoperative hand during this period was 2.7%, with the ring finger and middle finger most commonly involved (33.3 and 28.6%, respectively). Only history of prior TF in either hand was found to be a significantly associated on Chi-square analysis and multivariable regression ( p  < 0.001). Conclusion  In patients with carpal tunnel syndrome, ipsilateral TFs occurred after 6.83% of CTRs, compared with a rate of 2.7% in the nonoperative hand, making it an important possible outcome to discuss with patients. The thumb was more commonly involved in triggering in the surgical hand compared with the nonoperative hand. Patients with a history of prior TFs in either hand were more likely to develop an ipsilateral TF after CTR. Level of Evidence  This is a Level III, retrospective study.

Total Wrist Arthroplasty Alignment and Its Potential Association with Clinical Outcomes

Purpose  There is a lack of quantitative research that describes the alignment and, more importantly, the effects of malalignment on total wrist arthroplasty (TWA). The main goal of this pilot study was to assess the alignment of TWA components in radiographic images and compare them with measures computed by three-dimensional analysis. Using these measures, we then determined if malalignment is associated with range of motion (ROM) or clinical outcomes (PRWHE, PROMIS, QuickDash, and grip strength). Methods  Six osteoarthritic patients with a single type of TWA were recruited. Radiographic images, computed tomography images, and clinical outcomes of the wrists were recorded. Using posteroanterior and lateral radiographs, alignment measurements were defined for the radial and carpal components. Radiographic measurements were validated with models reconstructed from computed tomography images using Bland-Altman analysis. Biplanar videoradiography (<1mm and <1 degree accuracy) was used to capture and compute ROM of the TWA components. Linear regression assessed the associations between alignment and outcomes. Results  Radiographic measures had a 95% limit-of-agreement (mean difference ±  1.96 × SD) of 3 degrees and 3mm with three-dimensional values, except for the measures of the carpal component in the lateral view. In our small cohort, wrist flexion-extension and radial-ulnar deviation were correlated with volar-dorsal tilt and volar-dorsal offset of the radial component and demonstrated a ROM increase of 3.7 and 1.6 degrees per degree increase in volar tilt, and 10.8 and 4.2 degrees per every millimeter increase in volar offset. The carpal component's higher volar tilt was also associated with improvements in patient-reported pain. Conclusions  We determined metrics describing the alignment of TWA, and found the volar tilt and volar offset of the radial component could potentially influence the replaced wrist's ROM. Clinical Relevance  TWA component alignment can be measured reliably in radiographs, and may be associated with clinical outcomes. Future studies must evaluate its role in a larger cohort.

Biomechanics of the Distal Radioulnar Joint During In Vivo Forearm Pronosupination

Background  Ulnar variance (UV) and center of rotation (COR) location at the level of the distal radioulnar joint (DRUJ) change with forearm rotation. Nevertheless, these parameters have not been assessed dynamically during active in vivo pronosupination. This assessment could help us to improve our diagnosis and treatment strategies. Questions/purposes  We sought to (1) mathematically model the UV change, and (2) determine the dynamic COR's location during active pronosupination. Methods  We used biplanar videoradiography to study DRUJ during in vivo pronation and supination in nine healthy subjects. UV was defined as the proximal-distal distance of ulnar fovea with respect to the radial sigmoid notch, and COR was calculated using helical axis of motion parameters. The continuous change of UV was evaluated using a generalized linear regression model. Results  A second-degree polynomial with R 2 of 0.85 was able to model the UV changes. Maximum negative UV occurred at 38.0 degrees supination and maximum positive UV occurred at maximum pronation. At maximum pronation, the COR was located 0.5 ± 1.8 mm ulnarly and 0.6 ± 0.8 mm volarly from the center of the ulnar fovea, while at maximum supination, the COR was located 0.2 ± 0.6 mm radially and 2.0 ± 0.5 mm volarly. Conclusion  Changes in UV and volar translation of the COR are nonlinear at the DRUJ during pronosupination. Clinical Relevance  Understanding the dynamic nature of UV as a function of pronosupination can help guide accurate evaluation and treatment of wrist pathology where the UV is an important consideration. The dynamic behavior of COR might be useful in designing DRUJ replacement implants to match the anatomical motion.

Characteristics and Publication Rates for Podium Presentations at National Hand Surgery Meetings from 2007 to 2012

The purpose of this study was to evaluate and compare the research presented at the annual meetings of the American Society for Surgery of the Hand (ASSH) and the American Association for Hand Surgery (AAHS). Podium presentation data were extracted from the abstract books of the annual meetings of the ASSH and AAHS from 2007 to 2012. Corresponding publications were identified using searchable online publication databases and an algorithm linking authorship and content. The majority of research was clinical and the most common topics were trauma, degenerative conditions, and biomechanics. The most common body region of interest was the wrist/forearm. ASSH podium presentations were of a stronger level of evidence and were more likely to be published. The mean times to publication for research presented at the ASSH and AAHS meetings were 16.7 and 16.4 months, respectively. Presentations from each society were subsequently published at higher proportions in their affiliated journals. Furthermore, in comparison to AAHS presentations, a significantly larger proportion of research presented at the ASSH meetings was published in the Journal of Bone and Joint Surgery , while a larger proportion of AAHS presentations were published in Plastic and Reconstructive Surgery and Microsurgery .

Proximal-distal shift of the center of rotation in a total wrist arthroplasty is more than twice of the healthy wrist

Reproduction of healthy wrist biomechanics should minimize the abnormal joint forces that could potentially result in the failure of a total wrist arthroplasty (TWA). To date, the in vivo kinematics of TWA have not been measured and it is unknown if TWA preserves healthy wrist kinematics. Therefore, the purpose of this in vivo study was to determine the center of rotation (COR) for a current TWA design and to compare its location to the healthy wrist. The wrist COR for six patients with TWA and 10 healthy subjects were calculated using biplane videoradiography as the subjects performed various range-of-motion and functional tasks that included coupled wrist motions. An open-source registration software, Autoscoper, was used for model-based tracking and kinematics analysis. It was demonstrated that the COR was located near the centers of curvatures of the carpal component for the anatomical motions of flexion-extension and radial-ulnar deviation. When compared to healthy wrists, the COR of TWAs was located more distal in both pure radial deviation (P < .0001) and pure ulnar deviation (P = .07), while there was no difference in its location in pure flexion or extension (P = .99). Across all coupled motions, the TWA's COR shifted more than two times that of the healthy wrists in the proximal-distal direction (17.1 vs 7.2 mm). We postulate that the mismatch in the COR location and behavior may be associated with increased loading of the TWA components, leading to an increase in the risk of component and/or interface failure.

A Prospective Evaluation of the Effect of Supervised Hand Therapy After Carpal Tunnel Surgery

Background: The objective of this investigation is to examine the effect of postoperative therapy after routine carpal tunnel release. Our hypothesis was that supervised hand therapy does not improve outcomes after routine carpal tunnel release. Methods: Patients with carpal tunnel syndrome were randomly assigned to one of 3 groups based on the last digit of their medical record numbers to one of 3 groups: standard 6-week postoperative rehabilitation (standard therapy), expedited one-session postoperative rehabilitation group (expedited therapy), and no postoperative rehabilitation group (no therapy). The primary outcome measures were Quick Disabilities of the Arm, Shoulder, and Hand (QuickDASH) and return to work. The outcome questionnaire was completed preoperatively, at the 2-week follow-up visit, and monthly to 6 months after surgery. Results: All 3 treatment groups had similar mean QuickDASH scores preoperatively. At 1- to 6-month follow-up, all 3 groups had similar QuickDASH scores at each visit, and all showed a significant decline from baseline (preoperative) QuickDASH score. Overall, QuickDASH score decreased significantly from a preoperative visit mean of 42.7 to a final postoperative (visit 8) mean of 6.69. There was no significant difference in the mean QuickDASH score among all 3 groups at 6-month follow-up. There was no significance in the time of return to work among the 3 groups (standard therapy, 21.8 days; expedited therapy, 20.9 days; no therapy, 16.6 days). Conclusions: This investigation adds evidence that supervised hand therapy does not improve the outcomes of routine carpal tunnel surgery as measured by QuickDASH and return to work.

Cost-Effectiveness of Initial Revision Digit Amputation Performed in the Emergency Department Versus the Operating Room

Background: The objective of this study was to determine the comparative cost-effectiveness of performing initial revision finger amputation in the emergency department (ED) versus in the operating room (OR) accounting for need for unplanned secondary revision in the OR. Methods: We retrospectively examined patients presenting to the ED with traumatic finger and thumb amputations from January 2010 to December 2015. Only those treated with primarily revision amputation were included. Following initial management, the need for unplanned reoperation was assessed and associated with setting of initial management. A sensitivity analysis was used to determine the cost-effectiveness threshold for initial management in the ED versus the OR. Results: Five hundred thirty-seven patients had 677 fingertip amputations, of whom 91 digits were initially primarily revised in the OR, and 586 digits were primarily revised in the ED. Following initial revision, 91 digits required unplanned secondary revision. The unplanned secondary revision rates were similar between settings: 13.7% digits from the ED and 12.1% of digits from the OR (P = .57). When accounting for direct costs, an incidence of unplanned revision above 77.0% after initial revision fingertip amputation in the ED would make initial revision fingertip amputation in the OR cost-effective. Therefore, based on the unplanned secondary revision rate, initial management in the ED is more cost-effective than in the OR. Conclusions: There is no significant difference in the incidence of unplanned/secondary revision of fingertip amputation rate after the initial procedure was performed in the ED versus the OR.

Predicting Carpal Bone Kinematics Using an Expanded Digital Database of Wrist Carpal Bone Anatomy and Kinematics

The wrist can be considered a 2 degrees-of-freedom joint with all movements reflecting the combination of flexion-extension and radial-ulnar deviation. Wrist motions are accomplished by the kinematic reduction of the 42 degrees-of-freedom of the individual carpal bones. While previous studies have demonstrated the minimal motion of the scaphoid and lunate as the wrist moves along the dart-thrower's path or small relative motion between hamate-capitate-trapezoid, an understanding of the kinematics of the complete carpus across all wrist motions remains lacking. To address this, we assembled an open-source database of in vivo carpal motions and developed mathematical models of the carpal kinematics as a function of wrist motion. Quadratic surfaces were trained for each of the 42-carpal bone degrees-of-freedom and the goodness of fits were evaluated. Using the models, paths of wrist motion that generated minimal carpal rotations or translations were determined. Model predictions were best for flexion-extension, radial-ulnar deviation, and volar-dorsal translations for all carpal bones with R ²  > 0.8, while the estimates were least effective for supination-pronation with R ²  < 0.6. The wrist path of motion's analysis indicated that the distal row of carpal bones moves rigidly together (<3° motion), along the anatomical axis of wrist motion, while the bones in the proximal row undergo minimal motion when the wrist moves in a path oblique to the main axes. The open-source dataset along with its graphical user interface and mathematical models should facilitate clinical visualization and enable new studies of carpal kinematics and function. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:2661-2670, 2019.

Osteophyte growth in early thumb carpometacarpal osteoarthritis

OBJECTIVE

Osteophyte formation is a critical part of the degeneration of a joint with osteoarthritis (OA). While often qualitatively described, few studies have succeeded in quantifying osteophyte growth over time. Using computed tomography (CT) image data from a longitudinal, observational study of thumb carpometacarpal (CMC) OA, our aim was to quantify osteophyte growth volume and location over a three-year period in men and women.

METHOD

Ninety patients with early thumb OA were recruited and assessed at baseline, 1.5 years, and 3 years with CT imaging. Osteophyte volume and location on the trapezium and first metacarpal were determined using a library of 46 healthy subjects as a nonarthritic reference database.

RESULTS

There was a significant increase in osteophyte volume for women and men over the three-year follow-up in the trapezium (86.8 mm³-120.5 mm³ and 165.1 mm³-235.3 mm³, means respectively) and in the proximal metacarpal (63 mm³-80.4 mm³, and 115.8 mm³-161.7 mm³, respectively). The location of osteophyte initiation and growth was consistent across subjects and was located in non-opposing regions on the trapezium and first metacarpal. Osteophyte growth occurred about the radial and ulnar margins of the trapezial facet, while on the proximal metacarpal, growth occurred principally about the volar and dorsal margins of the facet.

CONCLUSION

Osteophyte growth occurred in early thumb osteoarthritis over three years. Growth was localized in specific, non-opposing regions on the trapezium and metacarpal, raising intriguing questions about the triggers for their formation, whether the mechanisms are mechanical, biological or a combination of both.

The Trapezium Dislocation: Case Presentation, Review of the Literature, Radiographic Analysis, Proposed Classification, and Treatment

BACKGROUND

Trapezium dislocations are rare injuries.

METHODS

A PubMed search of the term "trapezium dislocation" was conducted. Publications reporting a complete trapezium dislocation were included in the review.

RESULTS

The PubMed search resulted in 168 results. Fourteen publications reporting on 16 complete trapezium dislocations met inclusion criteria. A case of delayed diagnosis of a trapezium dislocation is presented. The literature is reviewed for pertinent clinically relevant information with respect to trapezium dislocations. A systematic method for radiographic analysis of trapezium dislocations and classification are described, and a treatment algorithm is presented.

CONCLUSIONS

Trapezium dislocations are infrequent injuries with few cases reported in the literature. Given the rarity of this injury, diagnosis and appropriate treatment may be delayed due to difficulty in recognition. Using the described method of radiographic analysis, delayed diagnosis may be avoided with implementation of timely treatment.

Risk Factors for 30-Day Complications After Thumb CMC Joint Arthroplasty: An American College of Surgeons National Surgery Quality Improvement Program Study

BACKGROUND

The first carpometacarpal (CMC) joint is a common site of osteoarthritis, with arthroplasty being a common procedure to provide pain relief and improve function with low complications. However, little is known about risk factors that may predispose a patient for postoperative complications.

METHODS

All CMC joint arthroplasty from 2005 to 2015 in the prospectively collected American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database were identified. Bivariate testing and multiple logistic regressions were performed to determine which patient demographics, surgical variables and medical comorbidities were significant predictors for complications. These included wound related, cardiopulmonary, neurological and renal complications, return to the operating room (OR) and readmission.

RESULTS

A total of 3344 patients were identified from the database. Of those, 45 patients (1.3%) experienced a complication including wound issues (0.66%), return to the OR (0.15%) and readmission (0.27%) amongst others. When performing bivariate analysis, age over 65, American Society of Anesthesiologists (ASA) Class, diabetes and renal dialysis were significant risk factors. Multiple logistic regression after adjusting for confounding factors demonstrated that insulin-dependent diabetes and ASA Class 4 had a strong trend while renal dialysis was a significant risk factor.

CONCLUSIONS

CMC arthroplasty has a very low overall complication rate of 1.3% and wound complication rate of 0.66%. Diabetes requiring insulin and ASA Class 4 trended towards significance while renal dialysis was found to be a significant risk factors in logistic regression. This information may be useful for preoperative counseling and discussion with patients who have these risk factors.

The AUSCAN and PRWHE Demonstrate Comparable Internal Consistency and Validity in Patients With Early Thumb Carpometacarpal Osteoarthritis

BACKGROUND

The Australian/Canadian Osteoarthritis Hand Index (AUSCAN) and Patient-Rated Wrist-Hand Evaluation (PRWHE) are 2 patient-related outcome measures to assess pain and disability in patients with osteoarthritis (OA). The purpose of this study was to evaluate the AUSCAN and PRWHE in a large-scale, longitudinal cohort of patients with early thumb carpometacarpal (CMC) OA.

METHODS

We obtained baseline data on 135 individuals (92 with early CMC OA participants and 43 asymptomatic controls) and at follow-up (year 1.5) on 83 individuals. We assessed the internal consistency using Cronbach alpha, and construct and criterion validity using other pain scales and objective measures of strength, respectively. We also examined the correlation between the AUSCAN and PRWHE and correlation coefficients at baseline and follow-up, as well as the correlation between changes in these instruments over the follow-up period.

RESULTS

Internal consistency was high for both AUSCAN and PRWHE totals and subscales (Cronbach α > 0.70). Both instruments demonstrated construct validity compared with the Verbal Rating Scale ( r = 0.52-0.60, P < .01), an assessment of pain, and moderate criterion validity compared with key pinch and grip strength ( r = -.24 to -.33, P < .05). These instruments were highly correlated with each other at baseline and follow-up time points ( r = 0.76-.94, P < .01), and changes in a patient's total scores over time were also correlated ( r = 0.83, P < .01).

CONCLUSIONS

The AUSCAN and PRWHE are both valid assessments for pain and/or disability in patients with early thumb CMC OA.

High Survivorship and Few Complications With Cementless Total Wrist Arthroplasty at a Mean Followup of 9 Years

BACKGROUND

Total wrist arthroplasty (TWA) has been described as traditionally being performed with fixation in the radius and carpus with cement. The TWA implant used in our series has been associated with promising results in studies with up to 6 years followup; however, studies evaluating survivorship, pain, and function with this implant are limited. QUESTION/PURPOSE: (1) To report ROM and pain scores after wrist reconstruction with cementless fourth-generation TWA at a mean followup of 9 years (range, 4.8-14.7 years). (2) To report complications of a cementless fourth-generation TWA and the cumulative probability of not undergoing a revision at a mean followup of 9 years.

METHODS

This is a retrospective case series of 69 patients who were treated for pancarpal wrist arthritis between 2002 and 2014. Of those, 31 had inflammatory arthritis (rheumatoid arthritis [n = 29], juvenile rheumatoid arthritis [n = 1], and psoriatic arthritis [n = 1]); all of these patients received TWA with the cementless implant studied in this investigation. Another 38 patients had osteoarthritis or posttraumatic arthritis; in this subgroup, 28 patients were 65 years or younger, and all underwent wrist fusion (none were offered TWA). Ten patients with osteoarthritis were older than 65 years and all were offered TWA; of those, eight underwent TWA, and two declined the procedure and instead preferred and underwent total wrist arthrodesis. The mean age of the 39 patients who had TWA was 56 ± 8.9 years (range, 31-78 years) at the time of surgery; 36 were women and three were men. The patients who underwent TWA were seen at a minimum of 4 years (mean, 9 years; range, 4-15 years), and all had been examined in 2016 as part of this study except for one patient who died 9 years after surgery. The dominant wrist was involved in 60% (25) of the patients. All patients were immobilized for 4 weeks postoperatively and then underwent hand therapy for 4 to 6 weeks. Pain and ROM were gathered before surgery as part of clinical care, and were measured again at latest followup; at latest followup, radiographs were analyzed (by the senior author) for evidence of loosening, defined as any implant migration compared with any previous radiograph with evidence of periimplant osteolysis and bone resorption. Subjective pain score was assessed by a verbal pain scale (0-10) and ROM was measured with a goniometer. Complications were determined by chart review and final examination. Kaplan Meier survival analysis was performed to estimate the cumulative probability of not undergoing a revision.

RESULTS

The mean preoperative active ROM was 34^o ± 18° flexion and 36° ± 18° extension. Postoperatively, the mean active ROM was 37° ± 14° flexion and 29° ± 13° extension. The mean difference between the preoperative pain score (8.6 ± 1.2) and postoperative pain score (0.4 ± 0.8) was 8.1 ± 1.9 (p < 0.001). Implant loosening occurred in three (7.7%) patients. No other complications occurred in this series. Kaplan-Meier survivorship analysis estimated the cumulative probability of remaining free from revision as 78% (95% CI, 62%-91%) at 15 years.

CONCLUSION

Cementless fourth-generation TWA improves pain while generally preserving the preoperative arc of motion. The cumulative probability of remaining free from revision at 14.7 years after the index procedure is 77.7% (95% CI, 62.0%-91.4%). Future studies should compare alternative approaches for patients with endstage wrist arthritis; such evaluations-which might compare TWA implants, or TWAs with arthrodesis-will almost certainly need to be multicenter, as the problem is relatively uncommon.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Flexor Tendon Ruptures After Distal Scaphoid Excision for Scaphotrapeziotrapezoid Osteoarthritis

BACKGROUND

Distal scaphoid excision is one treatment option for osteoarthritis of the scaphotrapeziotrapezoid (STT) joint following failure of conservative measures. Potential complications of this procedure include injury to the carpal ligaments, cartilage, and radial artery.

METHODS

A single case was identified by the senior author, and the medical record was reviewed for surgical notes, progress notes, and radiographs.

RESULTS

A 68-year-old male sustained ruptures of the flexor digitorum superficialis (FDS) and flexor digitorum profundus to the index finger 3 years following a distal scaphoid excision for symptomatic STT osteoarthritis. He required a flexor tendon reconstruction using the remaining FDS tendon for graft incorporated with a Pulvertaft weave. His midcarpal pain continued after recovery of his index finger function, eventually requiring a 4-corner fusion of the wrist.

CONCLUSIONS

Flexor tendon rupture is a previously unreported complication of distal scaphoid excision for STT arthritis.

The effects of partial carpal fusions on wrist range of motion

The objective of this investigation was to evaluate the effects of different partial wrist fusions on wrist motion. A total of 20 cadaveric wrists were tested in the intact state and after undergoing either a four-corner fusion or 2- and 3-bone fusion. The moment-rotation behaviour was measured in 24 directions of wrist motion about the forearm axis. The 2- and 3-bone fusion groups demonstrated increased radial deviation and pure flexion. Pure flexion was decreased in the four-corner fusion group. Radial extension and pure extension were decreased in all treatments compared with normal range of motion. Increasing the number of carpal bones within the fusion construct did not alter the functional axis of the wrist. Essentially equivalent motion is possible with 2-bone, 3-bone and four-corner fusions, with the exceptions of pure flexion and radial deviation. This data may influence surgeons when choosing between treatment methods.

LEVEL OF EVIDENCE

N/A.

Early osteoarthritis of the trapeziometacarpal joint is not associated with joint instability during typical isometric loading

The saddle-shaped trapeziometacarpal (TMC) joint contributes importantly to the function of the human thumb. A balance between mobility and stability is essential in this joint, which experiences high loads and is prone to osteoarthritis (OA). Since instability is considered a risk factor for TMC OA, we assessed TMC joint instability during the execution of three isometric functional tasks (key pinch, jar grasp, and jar twist) in 76 patients with early TMC OA and 44 asymptomatic controls. Computed tomography images were acquired while subjects held their hands relaxed and while they applied 80% of their maximum effort for each task. Six degree-of-freedom rigid body kinematics of the metacarpal with respect to the trapezium from the unloaded to the loaded task positions were computed in terms of a TMC joint coordinate system. Joint instability was expressed as a function of the metacarpal translation and the applied force. We found that the TMC joint was more unstable during a key pinch task than during a jar grasp or a jar twist task. Sex, age, and early OA did not have an effect on TMC joint instability, suggesting that instability during these three tasks is not a predisposing factor in TMC OA.

Men and women have similarly shaped carpometacarpal joint bones

Characterizing the morphology of the carpometacarpal (CMC) joint bones and how they vary across the population is important for understanding the functional anatomy and pathology of the thumb. The purpose of this paper was to develop a statistical shape model of the trapezium and first metacarpal bones to characterize the size and shape of the whole bones across a cohort of 50. We used this shape model to investigate the effects of sex and age on the size and shape of the CMC joint bones and the articulating surface area of the CMC joint. We hypothesized that women have similar shape trapezium and first metacarpal bones compared to men, following scaling for overall size. We also hypothesized that age would be a significant predictor variable for CMC joint bone changes. CT image data and segmented point clouds of 50 CMC bones from healthy adult men and women were obtained from an ongoing study and used to generate two statistical shape models. Statistical analysis of the principal component weights of both models was performed to investigate morphological sex and age differences. We observed sex differences, but were unable to detect any age differences. Between men and women the only difference in morphology of the trapezia and first metacarpal bones was size. These findings confirm our first hypothesis, and suggest that the women have similarly shaped trapezium and first metacarpal bones compared to men. Furthermore, our results reject our second hypothesis, indicating that age is a poor predictor of CMC joint morphology.

Correlation of clinical disease severity to radiographic thumb osteoarthritis index

PURPOSE

To determine if a slight modification of the 1987 Eaton-Glickel staging and interpreting 4 standardized radiographs for trapeziometacarpal (TMC) osteoarthritis (OA) improved analysis, to determine if a quantifiable index measurement from a single Robert (pronated anteroposterior) view enhanced reproducibility, and to examine whether improved radiographic staging correlated to clinically relevant disease and thus support validity.

METHODS

We analyzed 4 thumb radiographs (posteroanterior, lateral, Robert, and stress views) in 60 consecutive subjects representing an adult population spectrum of asymptomatic to advanced disease. Two experienced hand surgeons (A.L.L. and A.P.C.W.), 1 chief resident (A.J.B.), and 1 medical student (J.M.M.) performed the analysis on each subject's radiographs. We analyzed all 4 radiographs for Eaton and modified Eaton staging and then later analyzed only the Robert view for the thumb osteoarthritis (ThOA) index measurement. The radiographs were randomized and reread a week later for each classification at separate times. Surgically excised trapeziums from 20/60 subjects were inspected for first metacarpal surface disease and correlated to the 3 classifications.

RESULTS

All 3 staging classifications demonstrated high reproducibility, with the intraclass correlation coefficient averaging 0.73 for the Eaton, 0.83 for the modified Eaton, and 0.95 for the ThOA index. Articular wear and metacarpal surface eburnation correlated highest to the ThOA index, with advanced disease 1.55 or greater correlating to Eaton III/IV and modified Eaton stage 3/4 in a linear relationship.

CONCLUSIONS

The ThOA index based on a Robert view provided a measurable alternative to Eaton staging and correlated to severity of surgically relevant thumb TMC OA.

CLINICAL RELEVANCE

A simple reproducible radiographic measurement may enhance TMC OA classification and provide a reliable means to predict clinical disease.

TYPE OF STUDY/LEVEL OF EVIDENCE

Diagnostic II.

In Vivo kinematics of the trapeziometacarpal joint during thumb extension-flexion and abduction-adduction

PURPOSE

The primary aim of this study was to determine whether the in vivo kinematics of the trapeziometacarpal (TMC) joint differ as a function of age and sex during thumb extension-flexion (Ex-Fl) and abduction-adduction (Ab-Ad) motions.

METHODS

The hands and wrists of 44 subjects (10 men and 11 women with ages 18-35 y and 10 men and 13 women with ages 40-75 y) with no symptoms or signs of TMC joint pathology were imaged with computed tomography during thumb extension, flexion, abduction, and adduction. The kinematics of the TMC joint were computed and compared across direction, age, and sex.

RESULTS

We found no significant effects of age or sex, after normalizing for size, in any of the kinematic parameters. The Ex-Fl and Ab-Ad rotation axes did not intersect, and both were oriented obliquely to the saddle-shaped anatomy of the TMC articulation. The Ex-Fl axis was located in the trapezium and the Ab-Ad axis was located in the metacarpal. Metacarpal translation and internal rotation occurred primarily during Ex-Fl.

CONCLUSIONS

Our findings indicate that normal TMC joint kinematics are similar in males and females, regardless of age, and that the primary rotation axes are nonorthogonal and nonintersecting. In contrast to previous studies, we found Ex-Fl and Ab-Ad to be coupled with internal-external rotation and translation. Specifically, internal rotation and ulnar translation were coupled with flexion, indicating a potential stabilizing screw-home mechanism.

CLINICAL RELEVANCE

The treatment of TMC pathology and arthroplasty design require a detailed and accurate understanding of TMC function. This study confirms the complexity of TMC kinematics and describes metacarpal translation coupled with internal rotation during Ex-Fl, which may explain some of the limitations of current treatment strategies and should help improve implant designs.

The 2014 ABJS Nicolas Andry Award: The puzzle of the thumb: mobility, stability, and demands in opposition

BACKGROUND

The paradoxical demands of stability and mobility reflect the purpose and function of the human thumb. Its functional importance is underscored when a thumb is congenitally absent, injured, or afflicted with degenerative arthritis. Prevailing literature and teaching implicate the unique shape of the thumb carpometacarpal (CMC) joint, as well as its ligament support, applied forces, and repetitive motion, as culprits causing osteoarthritis (OA). Sex, ethnicity, and occupation may predispose individuals to OA.

QUESTIONS/PURPOSES

What evidence links ligament structure, forces, and motion to progressive CMC disease? Specifically: (1) Do unique attributes of the bony and ligamentous anatomy contribute to OA? (2) Can discrete joint load patterns be established that contribute to OA? And (3) can thumb motion that characterizes OA be measured at the fine and gross level?

METHODS

We addressed the morphology, load, and movement of the human thumb, emphasizing the CMC joint in normal and arthritic states. We present comparative anatomy, gross dissections, microscopic analysis, multimodal imaging, and live-subject kinematic studies to support or challenge the current understanding of the thumb CMC joint and its predisposition to disease.

RESULTS

The current evidence suggests structural differences and loading characteristics predispose the thumb CMC to joint degeneration, especially related to volar or central wear. The patterns of degeneration, however, are not consistently identified, suggesting influences beyond inherent anatomy, repetitive load, and abnormal motion.

CONCLUSIONS

Additional studies to define patterns of normal use and wear will provide data to better characterize CMC OA and opportunities for tailored treatment, including prevention, delay of progression, and joint arthroplasty.

Metakarpophalangeale Arthroplastik mit der NeuFlex-Silastikprothese

The NeuFlex joint implant is, like the Swanson prosthesis, a silicone-spacer-implant for metacarpophalangeal arthroplasty in rheumatoid arthritis or osteoarthritis. The implant design differs essentially through a preformed, 30 degrees anatomically neutral angle and palmar lying movement center, which reduces strain across the hinge by 35%. The Swanson prosthesis is straight with a dorsal lying movement center. The advantage of this new design is an improved overall function arc and range of movement in the MCP-joint with a better grip-function. Results of simulator and laboratory tests are presented and interpreted. In 50 patients (168 MCP-joints), early results show an average functional arc of movement of 61 degrees and an average extensor lag of 12 degrees. The 30 degrees pre-bend angle, corresponding to the normal resting angle of the hand, and the improved flexor tendon excursion and moment arm appear to be the main reasons for the substantially improved flexion following use of the NeuFlex device.