Pronator Quadratus Research Articles

Point-of-Care Ultrasound Pronator Quadratus Hematoma Sign for Detection of Clinically Non-Angulated Pediatric Distal Forearm Fractures: A Prospective Cohort Study.

Point-of-care ultrasound (POCUS) diagnosis of distal forearm fractures relies on the identification of buckling or breach of hyperechoic bone cortex. We describe the pronator quadratus hematoma (PQH) formation visualized on POCUS, the PQH sign, as it may aid diagnosis of pediatric distal forearm cortical breach fractures. A prospective cohort of children presenting to an emergency department with isolated, clinically non-angulated distal forearm injuries received POCUS by an expert emergency physician sonologist who identified the presence or absence of the PQH sign. They secondarily recorded the difference between the size of the pronator quadratus (PQ) muscle on both the affected and non-affected forearms (PQ delta thickness). Children received an x-ray subsequent to POCUS and were diagnosed based on an x-ray reported by a radiologist masked to POCUS findings. Thirty-eight children were recruited. All 22 patients with cortical breach fracture had PQH sign present (100%; 95%CI: 85-100%), while all 16 patients without cortical breach fracture had PQH sign absent (100%; 95%CI: 79-100%). PQ delta thickness ranged from 2.1 to 10.2 mm in cortical breach fractures, 0.0 to 1.1 mm in buckle fractures, and 0.2 to 0.8 mm in patients without fracture. The PQH sign correctly distinguished all children with, and without, cortical breach fractures. All PQ delta thicknesses were ≧2.1 mm when cortical breach fracture was present and ≦1.1 mm when cortical breach fracture was absent. The PQH sign and PQ delta thickness are promising measurements to identify pediatric distal forearm cortical breach fractures, and their utility should be confirmed in larger studies with sonologists of different abilities.

Correlation of Flexor Pollicis Longus Tendon Status by Ultrasonography with Plate Position on Radiographs Following Volar Plate Fixation of Distal Radius Fractures with Pronator Quadratus Repair

BackgroundPurpose was to correlate flexor pollicis longus tendon (FPL) attrition using Ultrasonography with plate position on radiographs following volar locked compression plate fixation (LCP) in patients who have undergone pronator quadratus (PQ) repair for distal radius fractures.MethodsStatus of flexor pollicis longus tendon was analyzed by ultrasonography in patients who underwent volar locked compression plating with pronator quadratus repair at a minimum of one year follow up. Soong’s criteria was used to assess the plate position and then correlated the ultrasonography findings of flexor pollicis longus.ResultsThere were 33 patients included in our study, of which 15 belonged to Soong’s grade zero, 10 were grade one and eight were grade two. Flexor pollicis longus attrition was noted in all cases with grade two plating.ConclusionPronator quadratus repair may not prevent attritional changes in higher grades of Soong’s, hence follow up may be required in these patients to identify attritional changes and early implant removal to prevent complications.

A Comparison of Pronator Quadratus Preservation and Dissection Approaches for Volar Plating of Comminuted Intra-articular Distal Radius Fracture.

Although the pronator quadratus (PQ) preservation approach for volar plating of distal radius fracture has been commonly used recently, its superiority to the conventional PQ dissection approach, especially for comminuted intra-articular distal radius fractures, has not been well established. The purpose of this study was to assess the efficacy of PQ preservation for comminuted intra-articular fractures and to evaluate the healed PQ during hardware removal surgery. From January 2014 to March 2019, 86 patients who underwent both volar plating for AO Foundation/Orthopedic Trauma Association classification type C2 or C3 distal radius fractures and subsequent hardware removal were assessed in this study. Radiographic measurements, clinical outcomes at each follow-up, and the integrity of healed PQ during hardware removal were compared between the PQ dissection (group D) and PQ preservation (group P) groups. Complete union with acceptable reduction on radiographic measurements was achieved in both groups. Group P showed a statistically significant earlier recovery of clinical outcomes at 2 weeks and 1 month postoperatively and improved anatomical restoration of PQ muscle covering the plate, which was identified during hardware removal surgery. Flexor tendon rupture was identified in 2 patients (5%) and tenosynovitis in 6 patients (14%) in group D; no patient had flexor tendon rupture (0%), and 2 patients (5%) had tenosynovitis in group P. Pronator quadratus preservation approach for volar plating is easily applicable and useful even for comminuted intra-articular distal radius fractures and is helpful for earlier restoration of wrist function and in preventing flexor tendon problems in the latter postoperative period.

What’s New in Hand and Wrist Surgery

What’s New in Hand and Wrist Surgery

Characterization of traumatized muscle-derived multipotent progenitor cells from low-energy trauma

BackgroundMultipotent progenitor cells have been harvested from different human tissues, including the bone marrow, adipose tissue, and umbilical cord blood. Previously, we identified a population of mesenchymal progenitor cells (MPCs) isolated from the traumatized muscle of patients undergoing reconstructive surgery following a war-related blast injury. These cells demonstrated the ability to differentiate into multiple mesenchymal lineages. While distal radius fractures from a civilian setting have a much lower injury mechanism (low-energy trauma), we hypothesized that debrided traumatized muscle near the fracture site would contain multipotent progenitor cells with the ability to differentiate and regenerate the injured tissue.MethodsThe traumatized muscle was debrided from the pronator quadratus in patients undergoing open reduction and internal fixation for a distal radius fracture at the Walter Reed National Military Medical Center. Using a previously described protocol for the isolation of MPCs from war-related extremity injuries, cells were harvested from the low-energy traumatized muscle samples and expanded in culture. Isolated cells were characterized by flow cytometry and q-RT-PCRs and induced to adipogenic, osteogenic, and chondrogenic differentiation. Downstream analyses consisted of lineage-specific staining and q-RT-PCR.ResultsCells isolated from low-energy traumatized muscle samples were CD73+, CD90+, and CD105+ that are the characteristic of adult human mesenchymal stem cells. These cells expressed high levels of the stem cell markers OCT4 and NANOG 1-day after isolation, which was dramatically reduced over-time in monolayer culture. Following induction, lineage-specific markers were demonstrated by each specific staining and confirmed by gene expression analysis, demonstrating the ability of these cells to differentiate into adipogenic, osteogenic, and chondrogenic lineages.ConclusionsAdult multipotent progenitor cells are an essential component for the success of regenerative medicine efforts. While MPCs have been isolated and characterized from severely traumatized muscle from high-energy injuries, here, we report that cells with similar characteristics and multipotential capacity have been isolated from the tissue that was exposed to low-energy, community trauma.

Treatment of Proximal Ulnar Stump after Darrach or Sauvé-Kapandji Procedure by Transfer of Insertion-Released Pronator Quadratus Pedicle.

Background: Treatment of the proximal ulnar stump with the Darrach or Sauvé-Kapandji (SK) procedure remains controversial. Ulnar wrist symptoms can result, and although many surgeons attribute these to ulnar stump instability, they can also be caused by radioulnar convergence or stump irritation. We present a novel surgical method for protecting the proximal ulnar stump and avoiding these complications. Methods: Our cases were five men and five women (mean age 72.0 years, range, 34-89). Mean follow-up duration was 41.7 months (range, 6-101 months). Radiological findings were osteoarthritis in five, rheumatoid arthritis of distal radioulnar joint in three, and ulnocarpal abutment syndrome in two. Pronator quadratus (PQ) was released from its insertion on the radius and transferred dorsally to cover the proximal ulnar stump. Postoperative ulnar wrist symptoms such as ulnar stump tenderness, forearm range of motion, and grip strength were compared with contralateral values. Dynamic radioulnar impingement was evaluated by Lee and Scheker's stress roentgenogram. Nine patients completed the Patient Rated Wrist Evaluation (PRWE) at final follow-up. Results: No patients reported ulnar wrist pain or tenderness at the proximal ulnar stump. Postoperative forearm range of motion recovered almost to contralateral values in cases without preoperative forearm contracture. In the two cases with contracture, postoperative pronation and supination recovered to more than their preoperative range. Grip strength averaged 86.4% (range, 66.7-103%) of the contralateral value at final follow-up. Lees and Scheker's stress roentgenogram revealed marked radioulnar impingement in one case, mild impingement in four cases and none in five, yet no patient complained of pain during the maneuver. The mean PRWE score was 34.7 points (range, 0-52.5 points). Conclusions: Insertion-released PQ pedicle transfer is an effective treatment option for the proximal ulnar stump after the Darrach or SK procedure.

CT Based Characterization of Volar Surface of Distal Radius: Can an Ideal Volar Plate for Fixation of Distal Radial Fractures be Designed?

Background: Literature has limited evidence concerning the morphology of volar surface of distal radius. A mismatch between the plate-contour and contour of the actual volar bony surface can result in malreduction. The purpose of this study is to analyze the normal curvature morphology of volar surface of distal radius and related parameters that can help in designing of the volar plates for fixation of distal radial fractures. Methods: We retrospectively analyzed CT scans of uninjured healthy distal radii performed during a one year period (2018-2019). The mediolateral extent of the pronator quadratus line, the mediolateral curve of the pronator quadratus line, the mediolateral surface angle between intermediate column and radial column of distal radius, the curvatures and locations of their vertices for radial and intermediate columns were measured. Results: A total of 84 CT-based studies were analyzed. The mediolateral extent of the pronator quadratus line, the mediolateral curve of the pronator quadratus line, and the mediolateral surface angle between intermediate column and radial column of the distal radius were 24.27 mm, 144.8 degrees and 163.1 degrees, respectively. The mean volar curvatures of the radial and intermediate columns were 156.5 and 151.4 degrees, respectively and distances of their vertices from the pronator-quadratus line were 10.96 mm and 14.13 mm, respectively. Conclusions: Considerable variations occur in curvature morphology of distal radial volar surface. A best fit rather than an anatomical fit can be considered during implant selection owing to these variations. Besides volar curvature of radial and ulnar columns, location of their vertices, mediolateral angulation and surface curvature between these columns at the level of watershed line should also be considered in plate selection. A combination of a few serial increments of the described parameters in the designs of volar fixation plates would be helpful for surgeons in the best implant selection.

Biomechanical Comparison of Pronator Quadratus Repair Techniques in the Modified Henry Approach for Distal Radius Fracture

Background: Open reduction and volar plate fixation of distal radius fracture frequently involve detaching the pronator quadratus muscle. Repair maybe difficult due to friable muscle fascia or bulky plate. This study evaluates the strength of 3 repair techniques. Methods and Results: Repair with separate Simple Sutures, Continuous Suture, or Suture Anchors was tested on 3 groups of 6 cadaver forearms. A distraction load was applied to all repairs on a traction simulator until there was a failure of either the suture, the muscle or the anchor. Simple Suture group could resist 20.7 N, the Continuous Suture group 33.3 N, and the Suture Anchors group 42.5 N. The load to displacement were, respectively, 20.0, 25.9, and 34.6 N. The mode of failure was noted. Conclusions: This cadaveric study shows that if deemed necessary for soft tissue coverage or for biological aid in fracture healing, suture anchor is the strongest repair choice for pronator quadratus. This conclusion must be weighed against the fact that no in vivo tensile strength value sustained by the pronator quadratus is known in the literature and that simple suture could be sufficient to hold the repaired muscle while the wrist is immobilized postoperatively.

The Dorsal Periosteal Curtain for Distal Radius Osteotomy Via the Volar Approach.

Volar wedge osteotomy and angle stable volar plating is now considered a standard approach for correction of distal radius malunion. In previous descriptions of the technique, soft tissue release has been performed with periosteal incision in line with the bony osteotomy. We present a technique whereby the dorsal periosteum is incised more proximally creating a dorsal vascularized periosteal "curtain." Our technique has several advantages including systematic release of restraining soft tissues to allow better distraction and reduction of the malunion; a dorsal periosteal curtain of vascular tissue with which to contain bone graft, protect extensor tendons and expedite healing; and better access to locally available bone graft. The previously described rotation-advancement of pronator quadratus is also used for plate coverage. We have found this technique straightforward to execute and teach, and useful in mitigating against some of the potential risks of the standard technique.

Bony Anatomy around the Watershed Line of the Distal Radius.

Background An important surgical landmark in the distal radius is the watershed line. The watershed line is a landmark for the positioning of volar locking plates (VLP) in the distal radius. Inconsistencies remain in the literature as to the presence and dimensions of landmarks in this compact area. We studied the detailed anatomy and dimensions of the distal radius with reference to bony anatomy around the watershed line, with special attention to the area between the pronator quadratus (PQ) and radial styloid. Materials and Methods The distal radius regions of 31 cadavers (23 right sided and 8 left sided) were dissected and studied. The heights at the junction of the scaphoid and lunate fossa, at the radial styloid, at the midpoint in between, and the widths of the PQ line, scaphoid, and lunate fossa were measured. The angle subtended by the pronator fossa and the radial styloid was also recorded. Results The mean heights at the junction of the scaphoid and lunate fossa, radial styloid, and midpoint in between were 5.1, 15.7, and 8.2 mm, respectively. The widths of the PQ line, scaphoid, and lunate fossa were 27, 19.4, and 10.6 mm, respectively. The mean angulation between the pronator fossa and the radial styloid was 128.9 degrees. Conclusion The area between the PQ and watershed line comprises a narrow area of bone which tapers to a point at its medial extent largely below the lunate fossa, thus it can hardly contain any implant proximal to the lunate fossa. The anterior orientation of this area and the concave anatomy of the articular surface mean careful screw direction is imperative to avoid inadvertent joint penetration. An angulation exists between the pronator fossa and the radial styloid, below the scaphoid fossa.

Minimally invasive anterior plate osteosynthesis of the distal radius: A 710 case-series

IntroductionSince the 2000s, internal fixation of distal radius fracture by volar locking plate on an extended flexor carpi radialis (FCR) approach has become the gold standard. ObjectiveThe present study aimed to assess medium-term results of minimally invasive plate osteosynthesis (MIPO) in distal radius fracture. Material and methodsThe series comprised of 710 cases (512 female; mean age, 58 years). The 15mm approach was on the lateral edge of the FCR. The plate was slipped under the pronator quadratus. Closure used intradermal running suture without drain or orthosis. ResultsAt a mean 7 months’ follow-up, mean scar length was 17mm (range, 10–40mm), pain 1.13/10 (0–8), Quick-DASH 13.28 (0–86.36), and patient-rated wrist evaluation (PRWE) 11.48 (0–91). Compared to contralateral values, mean flexion was 87.23%, extension 88.52%, pronation 96.17%, supination 93.41%, and grip strength 79.68%. Hardware was removed in 45.92% of cases. There were 16 cases of secondary displacement, with 4 revision procedures, one of sepsis at 6 months, 10 of complex regional pain syndrome, and 14 of median nerve paresthesia, with 4 carpal tunnel release procedures. DiscussionThe minimally invasive FCR approach can be used for volar plate fixation of distal radial fracture. It has the advantage of conserving ligamentotaxis, facilitating reduction and improving scar esthetics. The incision can be extended if need be. Level of evidenceIII; single-centre retrospective study.

Nerves transfers for functional hand recovery in traumatic lower brachial plexopathy.

Background: Distal nerve transfers are an innovative modality for the treatment of C8-T1 brachial plexus lesions. The purpose of this case series is to report the authors’ results with hand restoration function by nerve transfer in patients with lower brachial plexus injury.Methods: Three consecutive nerve transfers were performed in a series of 11 patients to restore hand function after injury to the lower brachial plexus: brachialis motor branch to anterior interosseous nerve (AIN) and supinator branch to the posterior interosseous nerve (PIN) in a first surgical procedure, and AIN to pronator quadratus branch of ulnar nerve between 4 and 6 months later.Results: In all, 11 male patients underwent 33 surgical procedures. Time between brachial plexus injury and surgery was a mean of 11 months (range 4–13 months). Postoperative follow-up ranged from 12 to 24 months. We observed recovery of M3 or better finger flexion strength (AIN) and wrist extension (PIN) in 8 of the 11 surgically treated upper limbs. These patients recovered full thumb and finger extension between 6 and 12 months of surgery, without significant loss of donor function.Conclusion: Nerve transfers represent a way of restoring volitional control of upper extremity function in patients with C8-T1 brachial plexus injury.

Pronator quadratus repair after volar plate fixation in distal radial fractures: evaluation of the clinical and functional outcome and of the protective role on the flexor tendons-a randomized controlled study.

The objective was to evaluate pronator quadratus (PQ) repair following volar plating of distal radial fractures on clinical and functional outcome, as well as flexor tendon friction, during the first 12months in ideally positioned plates (Soong 0). Confounding factors like variation in plate positioning, anatomical consolidation of the fracture and associated lesions were excluded. Eighty patients were included with distal radius fractures treated by volar locking plate in Soong grade 0 position, who were randomized to group PQ repair and group no repair. Sixty-five patients completed the 1-year follow-up: group PQ repair (n = 35) and group no repair (n = 30). Primary outcomes included range of motion, grip strength, pain level and QuickDASH. Secondary outcomes included distance between flexor pollicis longus (FPL) and volar rim and the largest distance between FPL and plate (soft tissue thickness occupied by PQ), assessed by ultrasonography. Mobility, grip strength and QuickDASH revealed no significant differences, except extension was significantly higher only in first 3months and radial deviation was significantly higher only at 6weeks after PQ repair. Pain level was significantly lower after PQ repair only in the first 3months. Distance between FPL and volar rim and the largest distance between FPL and plate were significantly higher after PQ repair. No friction contact between FPL and volar rim was measured in both groups at all measurement moments. Consequently, protective flexor tendon effect of PQ repair could consequently not be concluded. In conclusion, clinical and functional short term benefits, except improved wrist extension and reduced pain in the first 3months, were not proven in this study. In Soong grade 0, PQ repair is probably not necessary to prevent flexor tendon pathology. In Soong grade 1 or 2, this is still to be investigated. LEVEL OF EVIDENCE: 2.

PRONATOR QUADRATUS MUSCLE PEDICLED BONE GRAFT FOR DELAYED UNION SCAPHOID

Background: The human scaphoid bone is one of the carpal bones of the wrist. Its fracture is the most common type of carpal bone fracture. Scaphoid nonunion is a well-known and common problem. Both clinical and biological factors contribute to the development of nonunion. Several techniques of bone grafting have been used in the management of scaphoid fracture nonunion. The union rate achieved with standard nonvascularized bone grafts was poor, especially in case of avascular necrosis and pseudarthroses, whereas the use of vascularized bone grafts results in better union rates. Pronator quadratus pedicled bone graft is described as one of the successful techniques that treat delayed union of the scaphoid fracture. Objective: To evaluate the outcomes and results of pronator quadratus muscle pedicle bone graft for patients who were suffering from delayed union or nonunion of scaphoid bone fracture. Patients and Methods: Ten patients suffering from delayed and non-united scaphoid fractures, seven males and three females, aging from 17 to 54 years old. We used the pronator quadratus muscle pedicled bone graft to treat all these patients. Results: Complete union was achieved in seven patients, 6 patients of them were suffering from waist non united scaphoid fracture, and one patient of four patients suffering from non-united proximal pole scaphoid fracture. Conclusion: The use of the pronator quadratus pedicled bone graft in delayed union of the scaphoid waist fractures achieved a high rate of union with excellent and good functional outcomes. A poor result occurred on using the pronator quadratus pedicled bone graft in delayed union of the scaphoid proximal pole fracture.

PRONATOR QUADRATUS MUSCLE PEDICLED BONE GRAFT FOR DELAYED UNION SCAPHOID

Background: The human scaphoid bone is one of the carpal bones of the wrist. Its fracture is the most common type of carpal bone fracture. Scaphoid nonunion is a well-known and common problem. Both clinical and biological factors contribute to the development of nonunion. Several techniques of bone grafting have been used in the management of scaphoid fracture nonunion. The union rate achieved with standard nonvascularized bone grafts was poor, especially in case of avascular necrosis and pseudarthroses, whereas the use of vascularized bone grafts results in better union rates. Pronator quadratus pedicled bone graft is described as one of the successful techniques that treat delayed union of the scaphoid fracture. Objective: To evaluate the outcomes and results of pronator quadratus muscle pedicle bone graft for patients who were suffering from delayed union or nonunion of scaphoid bone fracture. Patients and Methods: Ten patients suffering from delayed and non-united scaphoid fractures, seven males and three females, aging from 17 to 54 years old. We used the pronator quadratus muscle pedicled bone graft to treat all these patients. Results: Complete union was achieved in seven patients, 6 patients of them were suffering from waist non united scaphoid fracture, and one patient of four patients suffering from non-united proximal pole scaphoid fracture. Conclusion: The use of the pronator quadratus pedicled bone graft in delayed union of the scaphoid waist fractures achieved a high rate of union with excellent and good functional outcomes. A poor result occurred on using the pronator quadratus pedicled bone graft in delayed union of the scaphoid proximal pole fracture.

Pronator quadratus pedicled bone graft for scaphoid non-unions

Scaphoid fractures frequently present with nonunion and proximal pole necrosis, the treatment of which is bone grafting. Pronator quadratus pedicled vascularized bone graft is an option especially in the setting of proximal pole necrosis. We describe our experience of managing such scaphoid non-unions using pronator quadratus pedicled vascularized bone graft. Six patients were managed using pronator quadratus pedicled vascularized bone graft following scaphoid fracture nonunion with proximal pole necrosis. All patients had good fracture healing and symptom resolution. Mild deficit in wrist extension was noted in all patients. Pronator quadratus pedicled vascularized bone graft is an attractive option for managing scaphoid nonunion. Lying adjacent to the fracture site, bone can be harvested and transferred without making any other incisions. This procedure introduces another source of blood supply to the fracture site and hence improves fracture healing.

Surgical comfort and clinical outcomes of MIPO with an extra-short plate designed for distal radius fractures.

Volar locking plates (VLPs) are increasingly used for distal radius fractures (DRFs) with minimally invasive plate osteosynthesis (MIPO), but surgery learning curves could be long. The purpose of this study was to assess a new extra-short plate with two locking diaphyseal divergent screws, specifically designed for MIPO, preserving the pronator quadratus muscle. This retrospective study consisted of three phases: (i) the evaluation of surgical comfort with the incision size and the duration of 59 consecutive surgeries using the extra-short plate in DRFs; (ii) the verification of the implant ability to maintain radiographic indices compared immediately postoperatively and at consolidation. They included radial inclination (RI), volar tilt (VT) and ulnar variance (UV); (iii) the assessment of clinical outcomes at last follow-up through: pain measured on the visual analogue scale (VAS), QuickDASH score, patient-rated wrist evaluation (PRWE) score, grip strength, range of motion and complications. In the first phase: mean incision size was 32mm, and mean operative time was 28.5min. In the second phase, there was no statistical difference between the two measures of the indices studied. In the third phase, mean follow-up time was 14.2months, VAS score was 1.1, QuickDASH score was 11.4/100, and PRWE score was 9.5/100. Flexion was 91%, extension was 94%, and grip strength was 86% compared to the contralateral side. The surgical comfort may be related to short operative time and incision. The implant allowed maintaining the radiographic indices without secondary displacement. Functional clinical outcomes were satisfactory. This extra-short plate design belongs to a novel generation of VLPs.

Diagnosis of Carpal Tunnel Syndrome using Shear Wave Elastography and High-frequency Ultrasound Imaging

The performance of ultrasound features from shear wave elastography (SWE) and high-frequency ultrasound imaging was evaluated independently and in combination to diagnose carpal tunnel syndrome (CTS). Twenty-five subjects were imaged in a sitting position with an arm extended and palm facing up. SWE of the medial nerve (MN) was acquired at the wrist level (site 1) and proximal to the pronator quadratus muscle (site 2). Cross-sectional area (CSA) and vascularity of the MN were assessed at the wrist using a 24 MHz probe. Color and power Doppler imaging (CDI and PDI), monochrome and color-coded Superb Microvascular Imaging (SMI) were performed for vascularity assessments. The diagnosis and severity of CTS was determined by clinical and electrodiagnostic tests. Diagnostic performance of the ultrasound features was assessed by t-tests, ANOVAs, and ROC analysis. The study included 20 control hands and 27 hands with CTS. All ultrasound features except for the stiffness ratio were significantly different between the CTS and control wrists (p<0.04). The stiffness of MN at site 1 showed a higher accuracy than at site 2. The combination of CSA and MN stiffness from site 2 showed an overall accuracy of 95% with a specificity and sensitivity of 100% and 93%, respectively. The CSA, MN stiffness from site 2, and CDI combination improved the accuracy to 96% with specificity and sensitivity of 100% and 93%, respectively. However, no ultrasound features (independently or in combination) differentiated all stages of CTS severity. SWE with high-frequency ultrasound imaging showed potential for the diagnosis of CTS.

The Vascular Basis of the Pronator Quadratus Muscle Flap and Its Use in Clinical Cases.

Background Pronator quadratus (PQ) is a deeply situated muscle in the forearm which may occasionally be utilized for soft-tissue reconstruction. The purpose of this anatomical and clinical study was to confirm vascular supply of PQ muscle (PQM) in order to optimize its transfer and confirm its utility in clinical situations. Methods In Part A of the anatomical study, fresh human cadavers ( n = 7) were prepared with an intra-arterial injection of lead oxide and gelatin solution, and PQM and neurovascular pedicle were dissected ( n = 14). In the anatomical study Part B, isolated limbs of embalmed human cadavers ( n = 12) were injected with India ink-gelatin mixture and PQ were dissected. Results PQ is a type II muscle flap, with one major pedicle, the anterior interosseous (AI) vessels and two minor pedicles from the radial and ulnar vessels. The mean dimensions of the muscle were 5.5 × 5.0 × 1.0 cm 3 , mean pedicle length was 9.6 cm, and the mean diameter of the artery and the vein was 2.3 mm and 2.8 mm, respectively. The dorsal cutaneous perforating branch (DPB) of the artery supplied the skin over the dorsal forearm and wrist. This branch also anastomosed with the 1, 2 intercompartmental supraretinacular artery (ICSRA). Conclusion This study confirms the potential utility and vascular basis of the PQM flap and its associated cutaneous paddle. In the clinical part, two patients with nonhealing wounds exposing the median nerve and flexor tendons in the distal forearm were treated using the PQM flap with good results.

Adaptations to cursoriality and digit reduction in the forelimb of the African wild dog (Lycaon pictus).

BackgroundThe African wild dog (Lycaon pictus), an endangered canid native to southern and eastern Africa, is distinct among canids in being described as entirely tetradactyl and in its nomadic lifestyle and use of exhaustive predation to capture its prey instead of speed, strength, or stealth. These behavioral and morphological traits suggest a potentially unique set of adaptations.MethodsHere, we dissected the forelimbs of an adult male L. pictus specimen and performed detailed descriptions and quantitative analyses of the musculoskeletal anatomy.ResultsStatistical comparisons of muscle masses and volumes revealed that L. pictus has relatively smaller wrist rotators (mm. pronator teres, pronator quadratus, supinator) than any other included carnivoran taxon, suggesting adaptive pressures for antebrachial stability over rotatory movement in the carpus of L. pictus. While a complete digit I is absent in L. pictus, a vestigial first metacarpal was discovered, resulting in changes to insertions of mm. extensor digiti I et II, abductor (et opponens) digiti I and flexor digiti I brevis. Mm. anconeus, brachialis and flexor carpi ulnaris caput ulnare all have more extensive origins in L. pictus than other canids suggesting an emphasis on posture and elbow stability. M. triceps brachii caput laterale has a larger origin in L. pictus and m. triceps brachii caput longum has an additional accessory head. Electromyographic studies have shown this muscle is active during the stance phase of trotting and galloping and is important for storing elastic energy during locomotion. We interpret these differences in size and attachments of muscles in L. pictus as adaptations for long distance running in this highly cursorial species, likely important for exhaustive predation. Absence of a full digit I in L. pictus may increase speed and stride length; however, the retention of a vestigial digit permits the attachment of reduced pollical muscles which may provide additional stability and proprioception to the carpus.