Hand muscle synergy in chopstick use: effect of object size and weight.

This study explains the role of muscle coordination in chopstick manipulation and investigates the effects of object width and weight on intrinsic and extrinsic hand muscle activity when picking up objects with chopsticks. Surface electromyography was used to measure the activity of the intrinsic and extrinsic hand muscles when picking up objects of varying widths and weights using chopsticks. The results revealed coordinated muscle activity patterns in the intrinsic and extrinsic hand muscles and coordination between them during chopstick manipulation. Object widths varying between 1 and 3 cm did not significantly affect muscle activity; however, object weight influenced muscle activity during both chopstick closing and object grasping, with greater muscle activity in the 40 g condition than in the 10 g condition. Intrinsic hand muscles were found to be involved in object grasping, regardless of object weight. These findings suggest that object weight should be considered when practicing picking up objects with chopsticks in scenarios resembling daily dining, to prevent excessive muscle activity during rehabilitation.

Three-dimensional motion analysis of pre- and postoperative thumb movement in trapeziometacarpal joint osteoarthritis-Comparison of arthrodesis and trapeziectomy with suspensionplasty.

Trapeziometacarpal osteoarthritis (TMC-OA) reduces the range of motion (ROM) of the thumb. However, the kinematic change achieved through surgical treatment remains unclear. Therefore, to quantify the kinematic change following TMC-OA surgery, we performed a three-dimensional motion analysis of the thumb using an optical motion capture system preoperatively and 1 year postoperatively in 23 patients with TMC-OA scheduled for arthrodesis (AD) or trapeziectomy with suspensionplasty (TS). Eighteen hands of nine healthy volunteers were also included as controls. Both procedures improved postoperative pain and Disability of the Arm, Shoulder and Hand scores, and AD increased pinch strength. The ROM of the base of the thumb was preserved in AD, which was thought to be due to the appearance of compensatory movements of adjacent joints even if the ROM of the TMC joint was lost. TS did not improve ROM. Quantifying thumb kinematic changes following TMC-OA surgery can improve our understanding of TMC-OA treatment and help select surgical procedures and postoperative assessment.

Effect of lateral wedge insole on medial meniscus extrusion and its association with knee osteoarthritis progression.

BACKGROUND: Medial meniscus extrusion (MME) is associated with knee osteoarthritis (OA) progression because of increased loading stress in the medial compartment of the knee. Using a lateral wedge insole (LWI) decreases loading stress and immediately reduces MME. OBJECTIVE: To investigate whether the wearing duration of LWI affects the midterm response to MME and is associated with knee OA progression. STUDY DESIGN: Cohort study. METHODS: Twenty-three patients with knee OA who were conservatively treated with LWI were classified according to the duration of the LWI wear per day: less than 5 h (short-duration group) or over 5 h (long-duration group). MME was evaluated in the single-leg standing position by ultrasound. Knee OA progression and limb alignment were evaluated radiographically. These evaluations were performed thrice: at the initial office visit as a baseline without LWI (time 0), with LWI (LWI-time 0), and 1 year after intervention with LWI (LWI-1 year). RESULTS: In both groups, the MMEs at LWI time 0 were significantly decreased compared with those at time 0. In the long-duration group, this reduction in MME was maintained 1 year after the intervention compared with time 0 (time 0: 3.9 ± 0.9, LWI-1 year: 2.6 ± 1.1), but this improvement was not observed in the short-duration group (time 0: 3.8 ± 1.7, LWI-1 year: 3.6 ± 1.7). In addition, three of four patients demonstrated OA progression, and varus alignment had significantly progressed compared with that at time 0 in the short-duration group. However, the long-duration group showed OA progression only in one patient and maintained limb alignment. CONCLUSIONS: The duration of wearing LWI affects the midterm reduction of MME and knee OA progression while maintaining limb alignment.

Association between three-dimensional motion analysis of the thumb and clinical parameters in patients with carpal tunnel syndrome.

We analysed the relationship between motor dysfunction of the thumb and the clinical parameters of carpal tunnel syndrome using three-dimensional motion analysis. This single-centred, prospective study included 65 hands in 51 patients with idiopathic carpal tunnel syndrome and 30 healthy hands. Three-dimensional thumb kinematics were acquired using a motion capture system with a retroreflective surface-based marker method. The trajectory area of thumb tip, adduction and abduction of the trapeziometacarpal joints and metacarpophalangeal joints were correlated with the clinical parameters. There was no significant correlation between the results of motion analysis values and patient-reported outcomes measures. Thumb movement disorder associated with carpal tunnel syndrome affected specific activities of daily living based on the pinching movements, such as 'writing' and 'buttoning clothes' among the patient-reported outcome measure items.Level of evidence: III.

Case Report: Virtual reality training for phantom limb pain after amputation.

Several reports have demonstrated the effectiveness of neurorehabilitation, such as mirror therapy or virtual reality, in treating phantom limb pain (PLP). This case study describes the effect of virtual reality training (VRT) on severe, long-term PLP and upper limb activity on the amputated side in a patient who underwent digit amputation 9 years prior. A woman in her 40 s underwent amputation of 2-5 fingers 9 years prior due to a workplace accident. She experienced persistent pain in the palms of her hand near the amputation sites. A single case design (ABA'B') was applied. Periods A and A' were set as periods without VRT intervention, and Periods B and B' were set as periods with VRT intervention. Periods A, B, A', and B' lasted 4, 10, 8, and 10 weeks, respectively. VRT was a task during which visual stimulation and upper limb movements were linked. The task consisted of catching a rolling ball in the display with a virtual hand, operated with both hands using a controller. VRT was performed once every 2-4 weeks for 30 min. Pain intensity was assessed using the short-form McGill Pain Questionnaire-2. Bilateral upper limb activity was measured continuously for 24 h using a triaxial accelerometer attached to the right and left wrist joints. The pain intensity was 147/220 points during Period A, 128 points during Period B, 93 points during Period A', and 100 points during Period B', showing a gradual decrease. Upper limb activity occurred mainly on the intact side during Periods A and B, whereas the activity on the amputated side increased 2-fold after Period A', and both upper extremities were used equally. Virtual reality training resulted in reduced pain intensity and increased activity in the upper limb. VRT may have induced reintegration of the sensory-motor loop, leading to a decrease in the PLP intensity. The upper limb activity on the amputated side may have also increased with the pain reduction. These results suggest that VRT may be valuable in reducing severe, long-term PLP.

Effect of transcranial static magnetic stimulation over unilateral or bilateral motor association cortex on performance of simple and choice reaction time tasks.

Background: Transcranial static magnetic stimulation (tSMS) is a non-invasive brain stimulation technique that place a strong neodymium magnet on scalp to reduce cortical excitability. We have recently developed a new tSMS device with three magnets placed close to each other (triple tSMS) and confirmed that this new device can produce a stronger and broader static magnetic field than the conventional single tSMS. The aim of the present study was to investigate the effect of the conventional single tSMS as well as triple tSMS over the unilateral or bilateral motor association cortex (MAC) on simple and choice reaction time (SRT and CRT) task performance. Methods: There were two experiments: one involved the conventional tSMS, and the other involved the triple tSMS. In both experiments, right-handed healthy participants received each of the following stimulations for 20 min on different days: tSMS over the unilateral (left) MAC, tSMS over the bilateral MAC, and sham stimulation. The center of the stimulation device was set at the premotor cortex. The participants performed SRT and CRT tasks before, immediately after, and 15 min after the stimulation (Pre, Post 0, and Post 15). We evaluated RT, standard deviation (SD) of RT, and accuracy (error rate). Simulation was also performed to determine the spatial distribution of magnetic field induced by tSMS over the bilateral MAC. Results: The spatial distribution of induced magnetic field was centered around the PMd for both tSMS systems, and the magnetic field reached multiple regions of the MAC as well as the sensorimotor cortices for triple tSMS. SD of CRT was significantly larger at Post 0 as compared to Pre when triple tSMS was applied to the bilateral MAC. No significant findings were noted for the other conditions or variables. Discussion: We found that single tSMS over the unilateral or bilateral MAC did not affect performance of RT tasks, whereas triple tSMS over the bilateral MAC but not over the unilateral MAC increased variability of CRT. Our finding suggests that RT task performance can be modulated using triple tSMS.

Effect of extension of the ulnar fingers on force control and muscle activity of the hand during a precision pinch.

Some individuals extend the three ulnar fingers when performing a precision pinch. The aim of the present study was to investigate the mechanisms and effect of the extension of the ulnar fingers during a pinch. When performing a pulp pinch task with the ulnar fingers in two positions (extension and flexion), 27 participants maintained 5% of their maximum force. The mean pinch force, force variability and time taken to reach the targeted force (reaching time) were calculated. Muscle activity was simultaneously measured, using surface electromyography, for nine muscles: the flexor pollicis brevis; abductor pollicis brevis; flexor pollicis longus; first lumbrical; first dorsal interosseous; flexor digitorum superficialis of the index finger; extensor indicis; and extensor digitorum of the index and ring fingers. No significant differences in the mean pinch force or force variability were found. However, the reaching time was significantly shorter (approximately 20% reduction) in the extension position and the activities in the flexor pollicis brevis, first lumbrical, extensor indicis and extensor digitorum of the ring finger were significantly higher. These findings suggest that extending the ulnar fingers during pinching enhances the activity of key muscles involved in the movement and allows for more rapid force exertion.

Measurement of the lumbrical muscle activity of the hand using electromyography supported by the ultrasound imaging technique with string navigation.

Although placing surface electrodes on small muscles by palpation is difficult, ultrasound guidance may enable electrode placement on the small muscles. This study aimed to examine whether ultrasound guidance is helpful for placement of electrodes on a small muscle, such as the hand lumbrical muscle. Twelve dominant hands of 12 healthy right-handed adults were included in this study. The first lumbrical muscle belly of the hands was identified using ultrasound guidance with a string navigation technique for placing surface electrodes. This technique was designed to identify the location of the center of the muscle belly under ultrasound imaging using a string. After the electrodes were placed on the muscle belly using this technique, the surface electromyographic signals of the first lumbrical, first dorsal interosseous, and adductor pollicis muscles were recorded. The activity of the lumbrical muscle could be separately measured of the first dorsal interosseous and adductor pollicis muscles. This technique has the potential to enable surface electromyography of small muscles for which placement of surface electrodes by palpation is challenging.

Effects of metacarpophalangeal joint position and finger joint movement speed on lumbrical muscle activity.

OBJECTIVES: The effect of metacarpophalangeal joint position and finger joint movement speed on lumbrical muscle activity remains unproven and was examined in this study. MATERIAL AND METHODS: Twenty-four healthy adults performed flexion-extension movements of the index finger in different metacarpophalangeal joint positions (extension or flexion) and movement speeds (60, 120, 240, and 360 beats per minute). The activities of the first lumbrical, first dorsal interosseous, and extensor digitorum muscles were evaluated using surface electromyography, and compared with those during finger joint extension. RESULTS: The metacarpophalangeal joint positions affected only lumbrical muscle activity, which was greater during extension. Further, finger movement speed affected the lumbrical and extensor digitorum muscle activities, which increased with increasing movement speeds. CONCLUSION: The present study suggests that position and movement speed can influence the lumbrical muscle activity during metacarpophalangeal joint extension. These findings may help expound lumbrical function and develop suitable strategies for inducing lumbrical muscle activity.

Differential Effects of Transcranial Static Magnetic Stimulation Over Left and Right Dorsolateral Prefrontal Cortex on Brain Oscillatory Responses During a Working Memory Task.

Transcranial static magnetic stimulation (tSMS) is known to influence behavioral and neural activities. However, although the left and right dorsolateral prefrontal cortex (DLPFC) are associated with different cognitive functions, there remains a lack of knowledge on a difference in the effects of tSMS on cognitive performance and related brain activity between left and right DLPFC stimulations. To address this knowledge gap, we examined how differently tSMS over the left and right DLPFC altered working memory performance and electroencephalographic oscillatory responses using a 2-back task, in which subjects monitor a sequence of stimuli and decide whether a presented stimulus matches the stimulus presented two trials previously. Fourteen healthy adults (five females) performed the 2-back task before, during (20 min after the start of stimulation), immediately after, and 15 min after three different stimulation conditions: tSMS over the left DLPFC, tSMS over the right DLPFC, and sham stimulation. Our preliminary results revealed that while tSMS over the left and right DLPFC impaired working memory performance to a similar extent, the impacts of tSMS on brain oscillatory responses were different between the left and right DLPFC stimulations. Specifically, tSMS over the left DLPFC increased the event-related synchronization in beta band whereas tSMS over the right DLPFC did not show such an effect. These findings support evidence that the left and right DLPFC play different roles in working memory and suggest that the neural mechanism underlying the impairment of working memory by tSMS can be different between left and right DLPFC stimulations.

Bone-based versus soft-tissue free flaps in lower extremity reconstruction.

BACKGROUND: Most lower extremity defects and minor bone defect wounds requiring a free flap are treatable with soft-tissue flaps, whereas large bone defect wounds are treated with bone-based flaps. This study aimed to compare bone-based and soft-tissue-free flaps in terms of operative procedures and postoperative complications, including long-term outcomes of lower extremity reconstruction. METHODS: This two-center retrospective cohort study collected data from all lower-extremity reconstructions with free flaps performed between March 2014 and February 2022; the level of evidence is considered to be therapeutic level III. We investigated the operative procedure and postoperative complications classified as being related to either bone-based or soft-tissue flaps. The data were further classified into the trauma and non-trauma groups and the long-term postoperative outcomes of patients who were followed up for ≥12 months were analyzed. RESULTS: A total of 122 free flaps were included: 29 bone-based flaps (1 scapular and 28 fibular flaps) and 93 soft-tissue flaps (22 muscle-based and 71 fasciocutaneous flaps). There was no significant difference in postoperative complications, including long-term outcomes, between the free flap types, regardless of etiology. Vein grafts were used more often for bone-based flaps than for soft-tissue flaps (20.7% vs. 7.5%; p = 0.045). The donor veins of bone-based flaps were more often anastomosed to superficial veins than were those of soft-tissue flaps (37.9% vs. 10.8%; p < 0.001). CONCLUSIONS: Using bone-based free flaps resulted in no significant differences in postoperative complications, including long-term outcomes, despite involving more complicated operative procedures than soft-tissue flaps. Thus, the use of vein grafts and anastomosis to the superficial venous system of the vascularized fibula graft may help avoid flap-related complications in bone-based free flaps.

The Effect of Lateral Wedge Insole on Gait Variability Assessed Using Wearable Sensors in Patients with Medial Compartment Knee Osteoarthritis.

Background: Lateral thrust seen in people with medial compartment knee osteoarthritis can cause dynamic knee instability and poor postural control during gait cycles. A lateral wedge insole can reduce the lateral thrust and may have a favorable effect on gait variability, which in turn may indicate gait instability improves. The aim of this study was to investigate the effect of lateral wedge insole on gait variability in knee osteoarthritis patients. Method: We involved 15 symptomatic knee osteoarthritis patients who were provided with lateral wedge insole and 13 healthy asymptomatic volunteers as the control group. The gait variability was evaluated as the coefficient of variation of stride, stance, and swing duration based on acceleration monitoring using a wearable sensor. The lateral thrust was estimated as the lateral acceleration peak on the shank sensor. These measurements were performed without lateral wedge insole (baseline), immediately with lateral wedge insole (T0) at the initial office visit and one month after intervention (T1). Result: Our data showed that the stance duration coefficient of variation and lateral thrust at T1 in the knee osteoarthritis group, were significantly decreased compared to the baseline values and these values were identical to those in the control group. Conclusion: The lateral wedge insole reduces dynamic knee instability and could improve gait variability in medial compartment knee osteoarthritis.

Risk assessment in delayed free flap reconstruction for severe lower extremity trauma.

PURPOSE: This study aims to identify serum biomarkers that contribute to vascular thrombosis and complete flap failure in delayed reconstruction with free flaps, as well as to develop a scoring system of risk assessment including these biomarkers. METHODS: A retrospective review of the database was conducted for lower extremity open fractures reconstructed between 7 and 90 days from injury, from March 2014 to February 2022. We investigated changes in platelet count (PLT), D-dimer, creatine phosphokinase (CPK), and C-reactive protein (CRP) and then, developed a risk assessment system including these biomarkers as risk factors. RESULTS: A total of 62 free flaps were enrolled, and vascular thrombosis occurred in 14 flaps (22.6%), 9 of which (14.5%) developed complete flap failure. The risk assessment score was set to a maximum of 6 points for 6 items: age ≤ 40 years, time from injury to coverage ≥ 14 days, zone of injury from middle to distal leg, D-dimer on the day of injury ≥ 60 µg/mL, maximum value of CPK ≥ 10,000 U/L, and maximum value of CRP ≥ 25 mg/dL. The best cutoff score was 3 in the vascular thrombosis model (sensitivity: 0.79, specificity: 0.77) and 4 in the complete flap failure model (sensitivity: 0.78, specificity: 0.92). CONCLUSIONS: Our risk assessment system showed that the risk of vascular thrombosis was high at ≥ 3 points and that of complete flap failure was high at ≥ 4 points. Significantly, elevated levels of D-dimer, CPK, and CRP require more caution during reconstruction using free flaps.

Point-of-care ultrasound in musculoskeletal field.

The musculoskeletal field is relatively new in point-of-care ultrasound (POCUS), a modality that has been gaining significance with the evolution of ultrasound (US) equipment and high-frequency probes. Images have become progressively clearer over the past decade, making it possible to diagnose many pathological conditions without exposure to radiation. Ultrasonography reveals many soft tissue pathologies that cannot be visualized using plain radiographs, which have historically been the first choice for the evaluation of musculoskeletal disorders. US saves money and time compared to magnetic resonance imaging (MRI). Although it is difficult to diagnose a disorder inside bone, its surface can be visualized very clearly, and it is also possible to visualize cartilage. Furthermore, with POCUS, it is possible to confirm a disorder and the continuity of the fibrous structures of muscles, tendons, and ligaments. In addition, the understanding of pathological conditions of motor disturbances, such as nerve or muscle/tendon injury, nerve paralysis, adhesions of the tendons, and joint instability, is deepened by observing the movement of these structures. Peripheral nerves, even small branches, can be visualized, and pathological conditions can be pinpointed by observing the nerve morphology, continuity, and relationship with the surrounding tissues. Children can be examined in a safe, relaxed environment, without leaving their parents. In addition, US is significantly different from other modalities in that it can be used for both diagnosis and treatment. Being able to visualize target sites improves safety and route accuracy of needle insertion for injection or puncture. Musculoskeletal POCUS is indispensable in routine medical care and is a technique that medical residents should acquire.

Knee adduction moment is correlated with the increase in medial meniscus extrusion by dynamic ultrasound in knee osteoarthritis.

BACKGROUND: An increase in medial meniscus extrusion (MME) due to abnormal biomechanical stress leads to knee osteoarthritis (OA) progression. MME evaluation during walking is a key method of detecting dynamic changes in the meniscus, and in combination with motion analysis, can provide a deeper understanding of the mechanisms involved in the increase of MME. OBJECTIVE: To validate the feasibility of MME dynamic evaluation in combination with a motion analysis system based on the correlation between the increase in MME and biomechanical factors. METHODS: Twenty-three knees from 23 patients with mild to moderate knee OA were analysed in this study. The medial meniscus during walking was evaluated by ultrasound. The increase in MME was calculated as the difference between the minimum and maximum MME during walking. A three-dimensional motion analysis system was synchronised with the ultrasound and then, biomechanical factors such as knee moment and ground reaction force were evaluated. RESULTS: The wave patterns of the mediolateral and vertical components of ground reaction forces and knee adduction moment were similar to those in the MME based on a high cross-correlation coefficient (>0.8). The increase in MME was significantly correlated with the peak value of the knee adduction moment (r = 0.54, P = 0.0073) but not with the mediolateral and vertical components of the ground reaction force. CONCLUSION: The findings show that knee adduction moment is correlated with an increase in MME during walking and indicates the validity and feasibility of the dynamic evaluation of MME in combination with a motion analysis system.

Dynamic response of medial meniscus extrusion to the lateral wedge insole is correlated with immediate pain reduction in knee osteoarthritis patients: real-time ultrasonographic study.

PURPOSE: To investigate the effect of lateral wedge insole (LWI) on medial meniscus extrusion (MME) observed during dynamic evaluation with ultrasound and its correlation with the alteration in knee pain in patients with knee osteoarthritis (OA). METHODS: This cohort study included 25 participants with knee OA. The medial meniscus was imaged during walking in video mode using ultrasonography. The degree of increase in MME (ΔMME) was calculated as the difference in the value of the maximum and minimum MME. The intensity of knee pain was evaluated immediately after the walking trial using the visual analogue scale (VAS). These measurements were performed with and without the LWI. The participants were categorised into the responder group, which was identified by the constant reduction in the VAS, and the non-responder group. RESULTS: MME, ΔMME, and knee pain during walking were significantly lower with the LWI than without the LWI (p < 0.01). The reduction in ΔMME with the LWI in the responder group was significantly higher than that in the non-responder group (p < 0.01). CONCLUSIONS: Our findings showed that MME and knee pain during walking decreased with LWI use, especially in patients whose reduction in knee pain was characterised by inhibition in the increase in MME observed during dynamic evaluation with ultrasound.

Correlation between kinesthetic motor imagery of an amputated limb and phantom limb pain.

BACKGROUND: Phantom limb pain (PLP) is a frequent painful sensation in amputees, and motor imagery (MI) is a useful approach for the treatment of this type of pain. However, it is not clear regarding the best MI modality for PLP. OBJECTIVES: The purpose of this study was to investigate the relationship between the PLP and MI modality in upper limb amputees. STUDY DESIGN: Observational study. METHODS: Eleven patients who underwent unilateral upper limb amputation participated in this study. The MI modality (kinesthetic and visual) and PLP intensity were evaluated using the Kinesthetic and Visual Imagery Questionnaire (KVIQ)-20 and a visual analog scale. MI ability was also assessed during the hand mental rotation task. We examined the correlation between MI modalities, ability, and pain intensity. RESULTS: The total KVIQ kinesthetic score was negatively correlated with pain intensity (r = -0.71, P < 0.01): the more vivid the kinesthetic imagery, the weaker the pain. In particular, the reduction in pain intensity was associated with strong kinesthetic imagery of opposing movements of the deficient thumb (r = -0.81, P < 0.01). The KVIQ visual score and MI ability were not associated with pain intensity. CONCLUSIONS: Our data showed that the reduction of PLP could be associated with the kinesthetic modality of MI but not with visual modality or MI ability. In other words, it was suggested that the more vivid the sensation of moving muscles and joints in the defect area, the lower the PLP intensity. To reduce PLP, clinicians may prefer interventions using the kinesthetic modality.

Analysis of Anastomotic Venous Factors in Traumatic Lower Extremity Injuries Reconstructed by Free Flap.

Background Venous thrombosis has been shown to be the most frequent cause of free flap failure in traumatic lower extremity injuries. However, the roles of various anastomotic venous factors, including venous anastomosis (end-to-end (ETE) or end-to-side (ETS)), venous outflow (one vein or two veins), and recipient venous selection (deep or superficial vein), remain unclear. This retrospective study aims to investigate factors contributing to microvascular complications in patients with lower extremity Gustilo type IIIB/IIIC injuries reconstructed by free flap with a focus on the three abovementioned venous factors. Methods A total of 44 flap treatment outcomes of 41 patients with these injuries from 2015 to 2020 were assessed according to the three venous factors (type of anastomosis, venous outflow, and vein selection). Results The average patient age was 52 years, with the majority (75.6%) being male. Eight patients (18.2%) returned to the operating room due to venous thrombosis, and five patients (11.4%) experienced total flap failure. The following factors were suspected to have contributed to venous thrombosis: vein size mismatch (n = 2) and recipient vein insufficiency possibly due to post-traumatic vessel disease (PTVD) (n = 6). End-to-side (ETS) anastomoses showed lower venous thrombosis rates than end-to-end (ETE) anastomoses (6.3% versus 25%, p = 0.22), two-vein outflows had lower rates than one (8.3% versus 30%, p = 0.07), and deep veins had the lowest thrombosis rates (7.7%), whereas superficial veins had the highest (38.5%). Conclusion The key venous factors in preventing venous thrombosis include using as many two-vein ETS anastomoses as possible to deep recipient veins.

Effect of the position of the interphalangeal joint on movements of the trapeziometacarpal joint during thumb opposition.

The Kapandji test is a simple method to score thumb opposition; however, the position of the interphalangeal joint of the thumb during this test has not been described. We aimed to quantitatively examine the effect of the thumb interphalangeal joint position on movements of the trapeziometacarpal joint during thumb opposition using the Kapandji test. The Kapandji test was carried out in 20 healthy participants during thumb interphalangeal joint extension and flexion. Movements of the joints and the activity of thenar muscles were recorded using motion capture and electromyography, respectively. We found that interphalangeal joint extension increased the trapeziometacarpal joint movement and thenar muscle activity compared with interphalangeal joint flexion, which contributed to thumb opposition at Kapandji Positions 0-6. These findings suggest the position of the thumb interphalangeal joint affects the trapeziometacarpal joint during thumb opposition, and assessment of thumb opposition using the Kapandji test is best done with the thumb interphalangeal joint in extension.

Arthroscopic mobilization for metacarpophalangeal joint extension contracture.

BACKGROUND: As a first-line surgical treatment for treating metacarpophalangeal (MCP) joint extension contractures, mobilization surgery with open dorsal approach has been indicated. However, this procedure has the possibility to result in postoperative recurrence over the course of time because its invasive open dorsal approach has a negative impact on the postoperative gliding of the extensor mechanism. We report the preliminarily outcomes of patients who underwent a minimally invasive arthroscopic mobilization to alter and enhance their existing surgical strategy in place of MCP joint extension contractures. METHODS: This retrospective study included seven patients with 13 MCP joint extension contractures who had received an arthroscopic release of the bilateral collateral ligament and/or dorsal capsule of affected MCP joint. The extension contractures were caused by long-time immobilization with inadequate extended position of the MCP joint after either hand and wrist fractures, extensor tendon injury, or peripheral nerve palsy. All patients received sufficient exercise under the supervision of a physical therapist for more than 3 months before surgery. However, physical therapy did not improve the MCP joint extension contractures. We measured the active and passive flexion angles preoperatively at 1 and 6 months after surgery. The passive flexion angle was also measured after arthroscopic mobilization on the operation table. Surgery-related complications regarding nerve, vessel, skin, and tendon were also assessed. RESULTS: In all patients, significant improvements were observed in both the active and passive flexion angles 1 month after surgery, and continued to improve 6 months after surgery. Two out of 13 metacarpophalangeal joints developed blisters on the dorsal side of the joint, but conservatively recovered. CONCLUSIONS: Based on the positive improvements observed in our patients, we conclude that this minimally invasive arthroscopic technique has the potential to alter and enhance the surgical treatment strategy for MCP joint extension contractures.