Extensor Medii Proprius: A Cadaveric Case Report

During routine dissection of 11 cadavers that originated with the Body Donor Program at Philadelphia College of Osteopathic Medicine (PCOM) Georgia, a 69-year-old African American male with bilateral extensor anomalies in the dorsal forearm compartment was encountered. The distinct muscle belly, identified as the extensor medii proprius (EMP), originated from the distal ulna and was inserted near the dorsal aponeurosis of the third digit. Manual traction of the right EMP tendon resulted in the extension of the third digit, suggesting the functional significance of the anomalous muscle. This case study analyzes the EMP found during dissection, as well as the anomalous muscle's prevalence, embryologic origin, and clinical relevance. The presence of the EMP muscle and tendon can be considered when assessing pain in the dorsum of the hand and when preparing for surgical repair or tendon transfer.

Anatomical Variations of the First Dorsal Compartment in de Quervain Tenosynovitis

BACKGROUND

De Quervain tenosynovitis of the wrist is a common pathology. The primary aim of this study is to determine the prevalence of extensor pollicis brevis and abductor pollicis longus (APL) anatomical variations in association with de Quervain tenosynovitis. The secondary aim was to compare additional patient-specific factors associated with de Quervain tenosynovitis.

METHODS

This retrospective study included 172 patients with de Quervain tenosynovitis who underwent first dorsal compartment release and 179 patients with thumb carpometacarpal (CMC) arthritis who underwent thumb CMC arthroplasty between August 1, 2007, and May 1, 2022. The CMC group was chosen as the control group because the study surgeons perform APL suspensionplasty as the primary procedure for thumb CMC arthritis, allowing for a comparison group without de Quervain tenosynovitis. Exclusion criteria included patients undergoing revision surgery, patients undergoing thumb CMC procedure other than APL suspensionplasty, and patients with both CMC and first dorsal compartment diagnoses. Demographics, clinical variables, and intraoperative findings were collected through retrospective chart reviews.

RESULTS

Patients in the de Quervain tenosynovitis group tended to be younger (51 years, range: 23-92 years vs 63 years, range: 28-85 years), women (86.1% vs 77.1%), and more commonly of African American or black race (15.7% vs 3.9%) and Asian race (5.2% vs 0%). There was a higher prevalence of tendon subcompartments (79.1% vs 64.2%), but fewer number of APL slips (38.3% vs 20.7% 2 or fewer slips) seen in the de Quervain tenosynovitis group.

CONCLUSION

Anatomical variation exists between patients with and without de Quervain tenosynovitis. The presence of tendon subcompartments but not an increased number of tendon slips is associated with de Quervain tenosynovitis.

The Challenges in restoration of extensor tendons function at the hand

INTRODUCTION

The authors discuss challenges in extensor function restoration at the finger level following distal posterior interosseous or tendon complex injuries, according to the typologies of lesions or the specific patient requirements.

MATERIALS

The authors report on two cases describing challenging resolutions. One patient with EDC lag from zone 6B to 8 requiring FCU prolonged with cadaveric grafts.  One young patient with distal posterior interosseous lesion requiring selective tendon transfers to EPL and EIP to restore selective and autonomous index extension.

RESULTS

In both cases the main goals were obtained, achieving high index of patient satisfaction and excellent outcomes with the restoration of the extension of the fingers.  Conclusions: In distal posterior interosseous nerve lesion, high demanding patients may require selective function to restore fine motor skills, such as autonomous index extension. In extensor tendons loss of substance from zone 6 to 8, involving musculotendinous junction proximally and short remnants distally, by-pass tendon transfer prolonged with cadaveric grafts is required. The authors highlight the techniques available as escape plan according to the necessary solutions.

Modalities of extensor tendon repair related to etiological factors and associated injuries

Aim To evaluate modalities of extensor tendons repair of hand and forearm in specific anatomical zones with regard to etiological factors and presence of associated injuries of adjacent anatomical structures. Methods This cross-sectional study included 279 patients referred for extensor tendon repair of hand and forearm in specific anatomical zones. Available treatment modalities were evaluated concerning etiological factors, anatomical zones, and associated injuries. Statistical significance was analysed in the occurrence of early and late postoperative complications according to anatomical zones. Results Direct repair of extensor tendon lesions was found to be the most common modality of reconstruction, 230 (93.5%), of which blade injuries were predominant, 120 (48.7%). Direct tendon repair was mostly indicated in Zone VI and Zone III, in 55 (23.9%) and 42 (18.3%) patients, respectively. Statistically, a significant correlation was confirmed between treatment modalities, injuries in specific anatomical zones, and type of etiological factor (p<0.0001). Statistical correlation was confirmed between zones of injuries and the occurrence of early and late complications (p=0.002). Conclusion Successful postoperative recovery was correlated with the recognition of functional failure in specific zones, assessment of potential associated injuries, and selection of the most optimal modality of reconstruction.

Intratendinous ganglion in the extensor digitorum communis

We encountered a patient with intratendinous ganglion which developed in the extensor digitorum communis tendon. Although its developmental mechanism is unclear, synovitis is considered the cause. For treatment, it may be necessary to prepare for tendon transfer and tendon grafting in consideration of the risk of tendon injury.

MRI Study on the Distance between the Distal Radius and the Flexor and Extensor Tendons: Is There Any Room for Error/Hardware?

Purpose  This study aims to quantify the distances between the cortex of the distal radius and flexor and extensor tendons. Methods  We analyzed 50 magnetic resonance images (MRI) of intact wrist without pathology. The distances between the volar cortex and the flexor pollicis longs (FPL), index flexor digitorum profunduns (FDPi), flexor digitorum profundus (FDP), and flexor digitorum superficialis (FDS) were measured at the level of the watershed line and 3- and 6-mm proximal to this level. The distances between the dorsal cortex and the extensor carpi radialis longus (ECRL), extensor carpi radialis brevis (ECRB), extensor pollicis longus (EPL), extensor indicis proprius (EIP), and the extensor digitorum communis (EDC) were measured at the level of Lister's tubercle and 5-mm distal to this level. Analysis was descriptive. Results  At the watershed line, the FPL, FDPi, FDP, and FDS were located at an average of 3.1, 2.4, 3.6, and 5.1 mm, respectively, volar to the volar cortex. The distances of the FDP and FDS increased at 3-mm proximal to the watershed line and increased for all four tendons at 6-mm proximal to the watershed line. Dorsally, at Listers' tubercle the ECRL, ECRB, EPL, EIP, and EDC were identified at an average of 0.7, 0.5, 0.5, 2.6, and 3.2 mm, respectively, dorsal to the dorsal cortex of the distal radius. At 5-mm more distal, these tendons were located on average 1.2, 1.0, 0.7, 1.9, and 1.8 mm, respectively, dorsal to the dorsal cortex. Conclusion  On the volar side, on average there is enough room for a volar plate when staying proximal to the watershed line. On the dorsal side, there is virtually no room for protruding screws as physical anatomical space is limited to a maximum of 0.7 mm from cortex to the closest tendon (the FDP), with screw increments being 2 mm. Level of Evidence  This is a Level II Study.

Predicting Tendon Tissue Grafting Source From the Extensors of Long Fingers: A Systematic Review of Cadaveric Studies

Background: The use of tendon tissue for transfer and grafting is a common practice in hand surgery. Many local tendons are usually used, mainly that of the palmaris longus muscle. However, this tendon could be absent in up to 46%. Extra slips of the extensor digitorum communis (EDC) and extra tendons such as the extensor indicis (EI) and the extensor digiti minimi (EDM) could be valuable sources for tendon tissue. Methods: A systematic review was conducted to quantify the proportion of extra slips in relation to each tendon and extra tendons in relation to each long finger. The aim is to better predict the location of tendon tissue sources on the dorsum of the hand in reconstructive surgery. Results: Based on 39 studies including 7847 hands, the cumulative frequencies of extra slips and extra tendons and the association between double-slip frequency and ancestry were as follows: (1) the little finger showed the highest cumulative frequency of extra slips (96.54%), followed by the ring (37.5%), long (30.6%), and index (9.5%) fingers; (2) the index with its EI and its variants and the little finger with its EDM bear by far the highest cumulative frequency of extra tendons (≈100%); and (3) double slips are found to be rare in Indian populations, most prevalent in Japanese populations, more prevalent in the index and little fingers of Caucasians, and more prevalent in the ring fingers of Middle Eastern populations. Conclusions: Knowledge of the frequencies of extra slips for each long extensor tendon and extra tendons for each long finger along with their prevalence in different populations would improve: (1) location prevision of tendon source for tendon grafting; and (2) surgical planning while supporting a patient-centered approach. Evidence-based hand anatomy would have a major potential to contribute to the practice of an evidence-based hand surgery. Predicting the possible tendon sources that could be present on the dorsum of the hand is thought to be very valuable for hand surgeons. In addition and from an evolutionary perspective, we hypothesized that the observed significantly higher frequency values of the double-slip and triple-slip types of the EDC of the ring finger, EDC of the little finger, and EDM might indicate a natural selection tendency for a higher independence of the former digits in the future evolution of the human hand.

Surgical Treatment of Tenosynovitis of Extensor Tendons of Fourth Compartment of Wrist in Nonrheumatoid Patients-A Case Series of 10 Patients in India

Purpose Proliferative tenosynovitis of the extensor tendons is a very common painful wrist condition that can occur both in presence and absence of rheumatoid arthritis (RA). This study aims to evaluate a series of patients without RA, having extensor tendon tenosynovitis, its pathology, and results of surgical treatment. Materials and Methods A consecutive series of 10 patients without RA, having tenosynovitis of fourth extensor compartment were treated surgically and evaluated in the study. All patients were operated upon by a single surgeon, and intraoperative specimens were sent for histopathologic evaluation by a single pathologist. The functional outcome of the patients was evaluated by comparing the post- and preoperative wrist extension. Results All patients presented with painful mass over dorsum of the wrist, overlying the fourth extensor compartment. On clinical examination, there was severe limitation of active wrist extension with extended fingers and improvement in wrist extension on flexing the fingers. All patients had significant improvement in wrist extension after surgery. The histopathologic examination of the intraoperative samples revealed similar findings of tenosynovitis in all cases, which was different than that seen in RA. Conclusion This study reveals a distinct tenosynovitis in a group of patients without RA resembling traumatic tenosynovitis on histopathologic examination. Radiologic and intraoperative findings reveal presence of nodular mass in the affected tendon due to proliferative tenosynovitis, which blocks effective proximal excursion of the tendon, leading to decreased wrist extension. This study shows that surgical treatment in the form of tenosynovectomy gives excellent relief to these patients. Type of Study This is a Level IV, therapeutic study.

Sonographic Characteristics of Extensor Tendon Abnormalities and Relationship With Joint Disease Activity in Rheumatoid Arthritis: A Pilot Study

OBJECTIVES

To characterize abnormalities in the dorsal extensor tendons of the hand and determine the importance of these findings in rheumatoid arthritis.

METHODS

A retrospective cross-sectional study was done on 26 patients with rheumatoid arthritis who had sonography of their hands. B-mode and power Doppler joint activity were scored, and the extensor tendons were examined for B-mode changes and power Doppler signals. B-mode changes included anechoic fluid around tendons, hypoechoic tissue around tendons, paratendon tissue and tendon thickening, as well as vascularity around the tendon, for which peritendon power Doppler signals were recorded.

RESULTS

Forty-one hands and 205 joints were reviewed. Anechoic fluid around the tendons and peritendon power Doppler signals were observed in 41% and 39%, respectively; 44% and 28% of patients had B-mode and power Doppler scores in the upper tertile, respectively. For both B-mode and power Doppler scores, 3 categories or tertiles were created, 0 to 0.9, 1 to 1.9, and 2 to 3. We reported the percentage of patients with power Doppler and B-mode scores in this category. The severity of synovitis was associated with anechoic fluid around the tendons and peritendon power Doppler signals according to the Cochran-Mantel-Haenszel test. The common odds ratio was 3.52 (95% confidence interval, 1.45- 8.53) for anechoic fluid around the tendons and severe synovitis. The common odds ratio was 2.52 (95% confidence interval, 1.13-5.63) for peritendon power Doppler signals and severe synovitis.

CONCLUSIONS

Findings at the dorsal extensor tendons were anechoic fluid around tendons, hypoechoic tissue around tendons, peritendon power Doppler signals, and tendon thickening. Patients with anechoic fluid and power Doppler signals were found to have more severe disease activity at the joints based on B-mode and power Doppler scores.

Treatment of swan neck deformity in cerebral palsy

Swan neck deformity in patients with cerebral palsy can result from hand intrinsic muscle spasticity or overpull of the digital extensors. After accurate identification of the etiology of the deformity, surgical treatment is directed at correcting the underlying muscle imbalance. Intrinsic lengthening can be used to treat intrinsic muscle spasticity, whereas central slip tenotomy is employed when digital extensor overpull is the deforming force. Accurate diagnosis and application of the proper surgical technique are essential when treating swan neck deformity in patients with cerebral palsy.