Influence of the pronator quadratus and supinator muscle load on DRUJ stability

Progress of fracture mapping technology based on CT three-dimensional reconstruction

Fracture Mapping is a new technology developed in recent years. This technology visually representing the morphology of fractures by overlaying fracture lines from multiple fracture models onto a standard model through three-dimensional reconstruction. Fracture mapping has been widely used in acetabular fracture, proximal humerus fractures, Pilon fracture, tibial plateau fractures, and so on. This technology provides a new research method for the diagnosis, classification, treatment selection, internal fixation design, and statistical analysis of common fracture sites. In addition, the fracture map can also provide a theoretical basis for the establishment of a biomechanical standardized fracture model. Herein, we reviewed various methods and the most advanced techniques for fracture mapping, and to discuss the issues existing in fracture mapping techniques, which will help in designing future studies that are closer to the ideal. Moreover, we outlined the fracture morphology features of fractures in various parts of the body, and discuss the implications of these fracture mapping studies for fracture treatment, thereby providing reference for research and clinical decision-making on bone and joint injuries to improve patient prognosis.

Pronator quadratus preserving versus pronator quadratus dissecting approaches in volar plate fixation of distal radius fractures: a systematic review of comparative studies

PURPOSE

To compare pronator quadratus preserving (PQ-P) approaches with PQ dissecting (PQ-D) approaches in volar plate fixation of distal radius fractures (DRFs).

METHODS

Three databases were searched on March 10th, 2024. The authors adhered to the PRISMA and R-AMSTAR guidelines and Cochrane Handbook for Systematic Reviews. Data on demographics, fracture classifications, patient reported outcome measures (PROMs), range of motion, radiographic parameters, and complications were extracted.

RESULTS

Thirteen studies with a total of 1007 fractures were included. Two of three studies reported lower DASH scores in the PQ-P group between 6 weeks and 3 months postoperative, however no studies reported lower scores in the PQ-P group after 3 months. Three of three studies reported significantly lower VAS scores at 6 weeks postoperative, however no studies reported significant differences after 6 months. Only one of six studies reported significantly greater flexion, extension, and pronation in the PQ-P group. One of four studies reported greater radial deviation in the PQ-P group, while there were no differences in supination or ulnar deviation. One of ten and one of six studies reported greater volar tilt and ulnar variance or radial length, respectively, in the PQ-P group.

CONCLUSION

There is not sufficient evidence supporting the utility of PQ-P approaches over conventional PQ-D approaches for volar plate fixation of DRFs, especially at long-term follow-ups (3+ months). There may be short term benefits with PQ-P approaches, specifically with regards to PROMs in the short-term (< 6 weeks), however there is limited high-quality evidence supporting these findings.

LEVEL OF EVIDENCE

Level III.

Evaluation of the treatment of distal radial volar fracture by different methods sparing the pronator quadratus

OBJECTIVE

The traditional volar approach requires the release of the pronator quadratus (PQ) muscle in the treatment of distal radius fractures. However, intraoperative repair of the PQ muscle often fails due to tissue injury and unstable muscle repair. This study compared the outcomes of different methods of sparing the PQ muscle combined with the volar plate in treating distal radius fractures.

METHODS

A total of 95 patients with distal radius fractures sparing the PQ muscle were enrolled with the brachioradialis (BR) splitting approach (group A, 33 people), the volar plating insertion PQ muscle approach (group B, 35 people) and traditional Henry approach without sparing PQ muscle (group C, 27 people). Postoperative internal fixation, fracture healing and postoperative complications were observed in the three groups. The visual analog scale (VAS) of postoperative wrist pain was compared between three groups. The Dienst joint scale was used to evaluate the wrist function of patients, and imaging indexes were used to evaluate the surgical efficacy.

RESULTS

A total of 95 patients with distal radius fractures were followed up for more than one year after surgery. All fractures obtained good union, with no vascular injury, nerve injury or wound infection. Outcomes at three days, one month and three months all showed no significant differences in postoperative imaging indexes among three groups and no significant differences in various indexes among three groups during the same period. The mean operative time in group C was significantly lower than that in groups A and B. There was significant difference in the mean operation time between group A and group B. The amount of mean operative blood loss or mean bone union time in groups A and B was significantly lower than those in group C. No significant difference was shown in mean operative blood loss or mean bone union time between group A and group B. No significant differences in limb function scores, VAS scores and the mean range of motion existed among three groups at the 12-month postoperative follow-up. However, outcomes assessed one week, one month and three months after surgery demonstrated significant differences in the VAS scores and the mean range of motion among three groups, and the group B had lower VAS score and greater the mean range of motion. According to Dienst score, the excellent rate in groups A, B and C was 91.0% (30/33), 94.2% (33/35) and 85.2% (23/27), respectively, at 12 months after surgery. Tendon irritation occurred in 2 cases and joint stiffness in 1 case in group A. In group B, there were 2 cases traumatic arthritis and 2 cases delayed carpal tunnel syndrome and 1 case tendon irritation. In group C, tendon irritation and delayed carpal tunnel syndrome occurred, respectively, in 3 cases.

CONCLUSION

Our results demonstrated that these two different surgical approaches were effective ways to reserve PQ and had good clinical outcomes. The volar plating insertion PQ muscle approach could reduce early postoperative pain, promote early activity and return to normal life, while the BR splitting approach was more advantageous in intraoperative fracture exposure and could shorten the operative time. However, some defects also existed. At 12 months of follow-up, no significant advantage was seen in sparing the PQ muscle. Therefore, surgeons should be aware of their individual characteristics and choose patients carefully.

Stability of the distal radioulnar joint with and without activation of forearm muscles

The purpose of this study was to quantify the effect of the flexor carpi ulnaris and the extensor carpi ulnaris muscles on distal radioulnar joint stability. The anteroposterior ulnar head translation in relation to the radius was measured sonographically when the forearm was in a neutral resting position and when the hand was actively pressed on to a surface, with and without intentional flexor carpi ulnaris and extensor carpi ulnaris activation, while also being monitored by an electromyogram. Data on 40 healthy participants indicated a mean anteroposterior translation in the distal radioulnar joint of 4.1 mm (SD 1.08) without and 1.2 mm (SD 0.54) with muscle activation. Our results indicate that intentional ulnar forearm muscle activation results in 70% less anteroposterior ulnar head translation and greater distal radioulnar joint stability. Therefore, the flexor carpi ulnaris and extensor carpi ulnaris muscles serve as dynamic stabilizers of the distal radioulnar joint. This finding may be clinically significant since ulnar forearm muscles strengthening may increase distal radioulnar joint stability.

Description of unusual osteochondral laminar fragment patterns in Distal Radius fractures

BACKGROUND

Distal radius fracture (DRF) is one of the most common fractures and, frequently, surgical treatment is mandatory in the presence of an intra-articular fracture. However, there are some unusual intra-articular fracture patterns, were it remains challenging to properly recognize and anatomically reconstruct the articular surface. The objective of the present study is to describe an intra-articular fracture pattern of the distal radius characterized by the presence of osteochondral laminar fragments, which could potentially require a different treatment to standard stabilization. We aim to answer the following questions: (1) What are the radiological characteristics of intra-articular DRFs with osteochondral laminar fragments (OCLF), (2) What is the prevalence of DRFs with OCLF relative to all intra-articular surgical DRFs, (3) What are the differences in epidemiological characteristics of patients with OCLF in relation to all patients with intra-articular DRFs, (4) What is the prevalence of intra-articular DRFs with OCLF in patients belonging to a closed community.

PATIENTS AND METHODS

We reviewed radiological and tomographic records of all adult patients operated on distal radius fractures at our institution. We analyzed tomographic characteristics; prevalence of osteochondral laminar fragments relative to all intra-articular surgical distal radius fractures and compared clinical and demographic characteristics of patients with osteochondral laminar fragments in relation to all patients with intra-articular fractures.

RESULTS

Two main groups according to the fracture pattern were described: group I, volar rim impacted OCLF (vOCLF); and group II, central impacted OCLF (cOCLF). Prevalence of OCLF relative to surgical intra-articular DRFs: 42/989 (4.2%); group I: 23/989 (2.32%); group II: 19/989 (1.92%). Characteristics of patients with OCLF compared to all patients with intra-articular DRFs: Significant differences were found in the five variables evaluated (age, less than 65 years, female, high energy fracture, and associated fractures). The global prevalence of DRFs with OCLF in patients affiliated with the medical care insurance system of our institution was 2 per 10,000 individuals (95% CI 1.4 to 2.9).

DISCUSSION

Global prevalence of these fragments relative to surgical intra-articular fractures was very low. However, despite being epidemiologically rare, it is important to identify these specific fracture patterns because their treatment can be challenging.

LEVEL OF EVIDENCE

IV (Observational/Descriptive); Cross sectional study.

Calcific tendinopathy of the pronator quadratus muscle: A rare site and cause of ulnar sided wrist pain

Ulnar -sided wrist pain is a common complaint and can present a diagnostic challenge for a musculoskeletal clinician. Calcific tendinopathy is a well-recognised disorder related to the deposition of calcium hydroxyapatite crystals within tendons. Classically, tendons around the shoulder and the hip joints are the most commonly affected sites. We report a rare site of calcific tendinopathy of the Pronator Quadratus muscle presenting with ulnar-sided wrist pain in a 36-year-old male posing a diagnostic dilemma. This case-report highlights the importance of a thorough clinical evaluation and crucial role of cross-sectional imaging in reaching a diagnosis of calcific tendinopathy of the Pronator Quadratus muscle as unusual cause of ulnar-sided wrist pain. This is the first reported case of calcific tendinopathy in pronator quadratus in the literature we could review.

Experience with Diagnosis and Management of Distal Radioulnar Joint Instability

Objective  The aim of this study is to review our cumulative experience with diagnosis and treatment of distal radioulnar joint (DRUJ) instability and to present our treatment algorithm. Materials and Methods  Retrospective review identified 112 patients who had 126 episodes of care for DRUJ instability at a single institution over a 21-year period. Those diagnosed acutely or subacutely were treated with immobilization of the wrist and elbow for 6 weeks, while those with chronic instability had anatomic reconstruction of the dorsal and palmar radioulnar ligaments with tendon autograft or an alternative arthroscopic treatment with our thermal annealing technique. Short-term treatment failures and surgical complications were recorded. Nonparametric statistical tests were used to analyze key long-term outcome measures including ulnar wrist pain and DRUJ stability indicated by the dorsopalmar stress test. Results  At mean 7-year follow-up, eight patients in the acute-injury cohort had statistically significant improvements in wrist pain and DRUJ instability ( p  < 0.001). In both the 22-patient anatomic reconstruction cohort and the 37-patient arthroscopically treated group, there were also statistically significant improvements in wrist pain and DRUJ stability ( p  < 0.001) at mean 9-year follow-up. The majority of patients in all three groups was satisfied with treatment outcome, though some required secondary procedures. Conclusion  Early clinical diagnosis of DRUJ instability using the dorsopalmar stress test provides an opportunity for effective nonsurgical treatment. For chronic presentation, we recommend our arthroscopic thermal annealing technique for mild or moderate instability and open anatomic reconstruction of the radioulnar ligaments for severe instability. Level of Evidence  This is a Level IV, therapeutic study.

Radiocapitellar joint pressures following transradial amputation increase during elbow motion

This study aimed to compare the contact area, mean pressure, and peak pressure of the radiocapitellar joint (RCJ) in the upper limb after transradial amputation with those of the normal upper limb during elbow flexion and forearm rotation. Testing was performed using ten fresh-frozen upper limbs, and the transradial amputation was performed 5 cm proximal to the radial styloid process. The specimens were connected to a custom-designed apparatus for testing. A pressure sensor was inserted into the RCJ. The biomechanical indices of the RCJ were measured during elbow flexion and forearm rotation in all specimens. There was no significant difference in the contact area between the normal and transradial amputated upper limbs. However, in the upper limbs after transradial amputation, the mean pressure was higher than that in the normal upper limbs at all positions of elbow flexion and forearm rotation. The peak pressure was significantly higher in the upper limbs after transradial amputation than in the normal upper limbs, and was especially increased during pronation at 45° of elbow flexion. In conclusion, these results could cause cartilage erosion in the RCJ of transradial amputees. Thus, methods to reduce the pressure of the RCJ should be considered when a myoelectric prosthesis is developed.

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

PURPOSE

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.

MATERIALS AND METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Fixation of distal radius fracture with volar locking palmar plates while preserving pronator quadratus through the minimally invasive approach

BACKGROUND

The volar locking plate technique with an L-shaped incision of the PQ muscle through the classic volar Henry approach is a popular method for treating distal radius fractures. Recently we revised and improved this traditional technique by performing mini-invasive surgery.

OBJECTIVE

The purpose of this study was to evaluate the clinical effects after fixation of distal radius fracture with volar locking palmar plates while preserving the pronator quadratus through minimally invasive approach.

METHODS

From May 2014 to March 2017, 58 patients (38 males and 21 females) with an age range of 22-72 years (mean age 44.6 years) and with distal radius fractures underwent open reduction and internal fixation with volar locking palmar plates. The patients were classified as 23A-2 through 23C-2 according to the Orthopedic Trauma Association fracture classification system. All surgeries were completed by one trained team. The group that received volar locking palmar plates of distal radius performed with the traditional method through Henry approach involved 33 patients (21 males and 12 females) and the group that received PQ through minimally invasive approach group involved 25 patients (16 males and 9 females). We compared the two groups for wrist pain, forearm range of motion, grip strength, preoperative complications and wrist functional recovery score.

RESULTS

The minimum follow-up for the whole cohort was one year. The differences between the two groups were significant in terms of wrist pain, forearm range of motion, grip strength and wrist function at 1, 2, 6 weeks postoperatively, but insignificant at 3 and 12 months postoperatively. In the minimally invasive group a case of limited extension of the forefinger 3 months postoperatively was found. No significant differences were found for preoperative complications and radiographs postoperatively.

CONCLUSION

Fixation with volar locking palmar plates through minimally invasive approach is a satisfactory and optional method in the treatment of distal radius fractures. This technique yields better early wrist function, shortens rehabilitation time and gets high psychological satisfaction.

Residual rotation of forearm amputation: cadaveric study

Background

The purpose of this study was to investigate residual rotation of patients with forearm amputation and the contribution of involved muscle to residual rotation.

Methods

Testing was performed using five fresh-frozen cadaveric specimens prepared by isolating muscles involved in forearm rotation. Amputation was implemented at 25 cm (wrist disarticulation), 18 cm, or 10 cm from the tip of olecranon. Supination and pronation in the amputation stump were simulated with traction of involved muscle (supinator, biceps brachii, pronator teres, pronator quadratus) using an electric actuator. The degree of rotation was examined at 30°, 60°, 90°, and 120° in flexion of elbow.

Results

Average rotation of 25 cm forearm stump was 148° (SD: 23.1). The rotation was decreased to 117.5° (SD: 26.6) at 18 cm forearm stump. It was further decreased to 63° (SD 31.5) at 10 cm forearm stump. Tendency of disorganized rotation was observed in close proximity of the amputation site to the elbow. Full residual pronation was achieved with traction of each pronator teres and pronator quadratus. Although traction of supinator could implement residual supination, the contribution of biceps brachii ranged from 4 to 88% according to the degree of flexion.

Conclusions

Close proximity of the amputation site to the elbow decreased the residual rotation significantly compared to residual rotation of wrist disarticulation. The preservation of pronosupination was 80% at 18 cm forearm stump. Although the pronator teres and the pronator quadratus could make a full residual pronation separately, the supinator was essential to a residual supination.

Sparing the pronator quadratus for volar plating of distal radius fractures: a comparative study of two methods

Objectives

The objective of this study was to compare the results of two methods for sparing the pronator quadratus in volar plating of distal radius fractures.

Methods

A total of 110 patients were randomized to volar plating with sparing of the pronator quadratus either by a transverse incision along the distal border of the pronator quadratus (Group A, 55 people) or by the brachioradialis splitting method (Group B, 55 people). The operative and radiation time, range of motion, grip strength, Disabilities of the Arm, Shoulder, and Hand (DASH) scores, Visual Analog Scale (VAS) scores, and complications were recorded.

Results

There were no significant differences in the mean operative time, radiation time, mean bone union time, or total complication rate between the groups. We found no significant differences in range of motion, grip strength, VAS scores, and DASH scores at any of the study intervals between the groups. Although neurapraxia of the superficial branch of the radial nerve was more common in Group B than in Group A (6.7% vs. 0%), the difference was not significant.

Conclusions

Both methods were efficient approaches for sparing the pronator quadratus and had similar clinical outcomes, but they had different indications.

Analyses of fracture line distribution in intra-articular distal radius fractures

Purpose

To assess the association between the fracture line distribution and the location of comminution in intra-articular distal radius fractures by building fracture mapping.

Patients/methods

Forty cases with intra-articular fractures of distal radius were enrolled in the current prospective clinical study. Fracture lines and comminution zones were identified by reduced three-dimensional computed tomography reconstructions and then graphically superimposed onto a standard template to create two-dimensional fracture maps, followed by the conversion into heating maps. Based on qualitative descriptive fracture mapping analyses, the patterns of intra-articular distal radius fractures were determined.

Results

It was observed that the highest fracture line intensity was located as an inverted “T” shape zone in the dorsal aspect of the joint with high incidence of fractures and the prominently intense color in heat mapping. The keystone projected area, the radial styloid process and the metacarpal radial side articular surface were found to be the least involved parts of the fracture. According to the mapping of the number and distribution of fracture lines, a new classification method for intra-articular fractures of the distal radius was redefined. Different surgical approaches and internal fixation techniques were proposed for different types. In this paper, we retrospectively compared the preoperative X-ray findings between different types. Based on the preoperative X-ray prediction, the distal intra-articular radius fractures were classified, so as to develop effective surgical strategies. In this study, a new surgical approach was attempted, but due to the lack of evidence-based evidence, long-term postoperative complications and hand function should be further evaluated.

Conclusion

This study redefines a new method for the classification of intra-articular fractures of the distal radius, which allows doctors to have a clearer understanding of the characteristics of distal radius fractures. Moreover, the application value in fracture diagnosis is more significant, and the best surgical approach is selected for different types.

The Effect of Dorsal Angulation on Distal Radioulnar Joint Arthrokinematics Measured Using Intercartilage Distance

Background  The effects of dorsal angulation deformity on in vitro distal radioulnar joint (DRUJ) contact patterns are not well understood. Purpose  The purpose of this study was to utilize intercartilage distance to examine the effects of forearm rotation angle, distal radius deformity, and triangular fibrocartilage complex (TFCC) sectioning on DRUJ contact area and centroid position. Methods  An adjustable implant permitted the creation of simulated intact state and dorsal angulation deformities of 10, 20, and 30 degrees. Three-dimensional cartilage models of the distal radius and ulna were created using computed tomography data. Using optically tracked motion data, the relative position of the cartilage models was rendered and used to measure DRUJ cartilage contact mechanics. Results  DRUJ contact area was highest between 10 and 30 degrees of supination. TFCC sectioning caused a significant decrease in contact area with a mean reduction of 11 ± 7 mm ² between the TFCC intact and sectioned conditions across all variables. The position of the contact centroid moved volarly and proximally with supination for all variables. Deformity had a significant effect on the location of the contact centroid along the volar-dorsal plane. Conclusion  Contact area in the DRUJ was maximal between 10 and 30 degrees of supination during the conditions tested. There was a significant effect of simulated TFCC rupture on contact area in the DRUJ, with a mean contact reduction of 11 ± 7 mm ² after sectioning. Increasing dorsal angulation caused the contact centroid to move progressively more volar in the sigmoid notch.

Arthrokinematics of the Distal Radioulnar Joint Measured Using Intercartilage Distance in an In Vitro Model

PURPOSE

Current techniques used to measure joint contact rely on invasive procedures and are limited to statically loaded positions. We sought to examine native distal radioulnar joint (DRUJ) contact mechanics using nondestructive imaging methods during simulated active and passive forearm rotation.

METHODS

Testing was performed using 8 fresh-frozen cadaveric specimens that were surgically prepared by isolating muscles involved in forearm rotation. A wrist simulator allowed for the evaluation of differences between active and passive forearm rotation. Three-dimensional cartilage surface reconstructions were created using volumetric data acquired from computed tomography. Using optically tracked motion data, the relative position of the cartilage models was rendered and used to measure DRUJ cartilage contact mechanics. The effects of forearm movement method and rotation angle on centroid coordinate data and DRUJ contact area were examined.

RESULTS

The DRUJ contact area was maximal at 10° supination. There was more contact area in supination than pronation for both active and passive forearm rotation. The contact centroid moved volarly with supination, with magnitudes of 10.5 ± 2.6 mm volar for simulated active motion and 8.5 ± 2.6 mm volar for passive motion. Along the proximal-distal axis, the contact centroid moved 5.7 ± 2.4 mm proximal during simulated active motion. These findings were statistically significant. The contact centroid moved 0.2 ± 3.1 mm distal during passive motion (not significant).

CONCLUSIONS

It is possible to examine cartilage contact mechanics of the DRUJ nondestructively while undergoing simulated, continuous active and passive forearm rotation. The contact centroid moved volarly and proximally with supination. There were higher contact area values in supination compared with pronation, with a peak value at 10° supination.

CLINICAL RELEVANCE

This study documented normal DRUJ arthrokinematics using a nondestructive in vitro approach. It further reinforced the established biomechanical and clinical literature on contact patterns at the native DRUJ during forearm rotation.

Rehabilitation of distal radioulnar joint instability

Distal radioulnar joint (DRUJ) instabilities are common and often combined with other injuries of the interosseous membrane and/or the proximal radioulnar joint. Once they are diagnosed and the treatment is chosen, physiotherapists have limited choices due to the lack of validated protocols. The benefits of proprioception and neuromuscular rehabilitation have been brought to light for the shoulder, knee and ankle joints, among others. However, no program has been described for the DRUJ. The purpose of this article is to study the muscular elements responsible for active DRUJ stability, and to propose a proprioceptive rehabilitation program suited to this condition.

A Biomechanical Perspective on Distal Radioulnar Joint Instability

Background The purpose of this article was to review the anatomy, kinematics of the distal radioulnar joint (DRUJ), and to discuss definition, classification, and diagnosis of DRUJ instability. Methods A biomechanical perspective on physical examination of DRUJ ballottement test was documented. Physiological dynamic DRUJ translation and differences of the translation following sequential ligament sectioning and changes in different forearm and wrist positions were demonstrated. The clinical significance of each ligament's contribution to joint stability in specific wrist positions was addressed. Conclusion Each ligament stabilizing the DRUJ contributed to joint stability depending on the direction (palmer or dorsal) and different positions of the wrist and forearm. DRUJ ballottement test in each wrist and forearm position may detect tears of specific ligament stabilizing the DRUJ.

A Brachioradialis Splitting Approach Sparing the Pronator Quadratus for Volar Plating of the Distal Radius

Fractures of the distal radius account for up to 15% of all extremity fractures. Volar plating has become more popular, as it allows locking plate technology to be applied. Traditionally, access to the volar radius has been achieved through the approach of Henry using the interval between flexor carpi radialis and the radial artery, involving incising the radial border of the pronator quadratus (PQ). With this approach, PQ repair is difficult, and when attempted is often incomplete or tenuous, as it is a direct muscle-to-muscle repair. Theoretical advantages of repairing the PQ include the provision of plate coverage, a protective gliding layer, a well-vascularized coverage of the fracture fragments, and a protective barrier against deep infection in the case of superficial infection. Techniques have been developed to try and improve on the Henry approach. We have developed a surgical approach to volar plating that utilizes the anatomic relationship between brachioradialis and PQ in a way that allows simple and stable reattachment of the PQ muscle. We have termed the technique the "Brachioradialis splitting" approach. We present it here.

Effect of Volarly Angulated Distal Radius Fractures on Forearm Rotation and Distal Radioulnar Joint Kinematics

PURPOSE

To examine the effect of volar angulation deformities of the distal radius with and without triangular fibrocartilage complex (TFCC) rupture on forearm range of motion and the kinematics of the ulnar head at the distal radioulnar joint (DRUJ) during simulated active forearm rotation.

METHODS

Volar angulation deformities of the distal radius with 10° and 20° angulation from the native orientation were created in 8 cadaveric specimens using an adjustable apparatus. Active supination and pronation were performed using a forearm motion simulator. Pronation and supination range of motion was quantified with each deformity. In addition, changes in the dorsovolar position of the ulnar head relative to the radius were calculated after simulating each distal radial deformity. Testing was performed with the TFCC intact and sectioned.

RESULTS

Volar angulation deformities of 20° decreased the supination range with preservation of pronation. There was no effect of TFCC status on the range of forearm rotation. With the TFCC intact, volar angulation deformities translated the ulna slightly dorsally in pronation and volarly in supination. After sectioning the TFCC, volar angulation deformities of 10° and 20° translated the ulna dorsally throughout forearm rotation.

CONCLUSIONS

Volar angulation deformities reduce supination range and alter the DRUJ kinematics. The increased tension in the intact TFCC caused by volar angulation deformities likely prevented the expected dorsovolar displacement at the DRUJ and restricted supination. Dividing the TFCC released the constraining effect on the DRUJ and allowed the ulna to translate dorsally. However, supination remained limited, presumably because of impediment from the dorsally subluxated ulna.

CLINICAL RELEVANCE

This study demonstrated the importance of correcting volar angulation deformities of the distal radius to less than 20° in order to maintain normal range of forearm rotation and to less than 10° to maintain normal DRUJ kinematics when the TFCC is ruptured.

Effect of volar angulation of extra-articular distal radius fractures on distal radioulnar joint stability: a biomechanical study

The relationship between increased volar tilt of the distal radius and distal radioulnar joint stability was examined. Distal radioulnar joint stiffness was recorded at 10° intervals from 10° dorsal angulation to 20° of volar angulation from the anatomical position of the radius. Tests were performed with the intact radioulnar ligament and repeated after partial and then complete sectioning of the radioulnar ligament at the ulnar fovea. With the intact radioulnar ligament, distal radioulnar joint stiffness increased significantly at 10° and 20° of volar angulation. Partial sectioning of the radioulnar ligament resulted in an approximate 10% decrease of distal radioulnar joint stiffness compared with the intact state, but distal radioulnar joint stiffness still increased significantly with greater volar tilt. Complete sectioning of the radioulnar ligament significantly decreased distal radioulnar joint stiffness, and increasing the volar tilt did not result in increased distal radioulnar joint stiffness. These results suggest that volar angulation deformities of the distal radius should be corrected to 10° of volar tilt when the triangular fibrocartilage complex is intact. Level of evidence: N/A.

Volar subluxation of the ulnar head in dorsal translation deformities of distal radius fractures: an in vitro biomechanical study

OBJECTIVES

To quantify the effects of dorsal translation deformities of the distal radius with and without dorsal angulation on volar displacement of the ulnar head during simulated active forearm rotation, both with the triangular fibrocartilage complex (TFCC) intact and sectioned conditions.

METHODS

Eight fresh-frozen cadaveric upper extremities were mounted in an active forearm motion simulator, and distal radial deformities of 0, 5, and 10 mm of dorsal translation with 0, 10, 20, and 30 degrees of dorsal angulation were simulated. Volar displacement of the ulnar head at the distal radioulnar joint as a result of each distal radial deformity was quantified during simulated active supination. The data were collected with the TFCC intact and after sectioning the TFCC at its ulnar insertion.

RESULTS

Increasing isolated dorsal translation deformities increased volar displacement of the ulnar head when the TFCC was intact (P < 0.001). Increasing dorsal translation combined with dorsal angulation increased volar displacement of the ulnar head compared with isolated dorsal angulation deformities (P < 0.001). Sectioning the TFCC increased the volar displacement of the ulnar head caused by each distal radial deformity (P = 0.001).

CONCLUSIONS

These results emphasize the clinical importance of evaluating the magnitude of both dorsal translation and dorsal angulation when managing displaced distal radius fractures and malunions.

Load transfer at the distal ulna following simulated distal radius fracture malalignment

PURPOSE

To measure the effects of distal radius malalignment on loading at the distal ulna.

METHODS

Using an adjustable mechanism to simulate angulated and translated malalignments, clinically relevant distal radius deformities were simulated in a cadaveric model. A custom-built load cell was inserted just proximal to the native ulna head to measure the resultant force and torque in the distal ulna. Loads were measured before and after transecting the triangular fibrocartilage complex (TFCC).

RESULTS

There was an increase in distal ulna load and torque with increasing dorsal translation and angulation. Combined conditions of angulation and translation increased force and torque in the distal ulna to a greater extent than with either condition in isolation. Transecting the TFCC resulted in a reduction in distal ulna load and torque.

CONCLUSIONS

A progressive increase in load at the distal ulna was observed with increasing severity of malalignment, which may be an important contributor to residual ulnar wrist pain and dysfunction. However, no clear-cut threshold of malalignment of a dorsally angulated and translated distal radius fracture was identified. These observations suggest that radius deformities cause articular incongruity, which increases TFCC tension and distal radioulnar joint load. Cutting of the TFCC decreased distal ulna loading, likely by releasing the articular constraining effect of the TFCC on the distal radioulnar joint, allowing the radius to rotate more freely with respect to the ulna.

CLINICAL RELEVANCE

Anatomical reduction of a distal radius fracture minimizes the forces in the distal ulna and may reduce residual ulnar wrist pain and dysfunction.

Effect of wrist position on distal radioulnar joint stability: a biomechanical study

We investigated distal radioulnar joint (DRUJ) stability in different wrist positions and examined the relative contribution of each ligamentous component of the triangular fibrocartilage complex (TFCC) to DRUJ stability. We used nine fresh-frozen cadavers. The humerus and ulna were fixed at 90° elbow flexion. The radiocarpal unit was translated relative to the ulna in dorsopalmar directions with the wrist in five positions. Displacement of the unit was measured by an electromagnetic tracking device. Magnitudes of displacement were compared between different wrist positions in various sectioning stages: ulnocarpal ligament (UCL) sectioning, radioulnar ligaments (RUL) sectioning, and extensor carpi ulnaris (ECU) floor sectioning. Wrist position and sectioning stage significantly influenced the displacement. In intact wrists, the displacement in wrist extension was significantly lower than that in neutral. However, after UCL sectioning, there were no longer any significant differences. After RUL sectioning, the displacement in radial deviation was significantly lower than that in neutral. Following ECU floor sectioning, there were no longer any significant differences. Thus, in intact wrists, DRUJ stability in wrist extension is likely due to tightening of the UCL. After complete RUL sectioning, DRUJ is stabilized in radial deviation due to tightening of the ECU floor.

Examination of the pronator quadratus muscle during hardware removal procedures after volar plating for distal radius fractures

BACKGROUND

It is not clear whether the pronator quadratus (PQ) muscle actually heals and provides a meaningful pronation force after volar plating for distal radius fractures (DRFs). We aimed to determine whether the length of the PQ muscle, which is dissected and then repaired during volar plating for a DRF, affects the forearm rotation strength and clinical outcomes.

METHODS

We examined 41 patients who requested hardware removal after volar plating. We measured the isokinetic forearm rotation strength and clinical outcomes including grip strength, wrist range of motion, and disabilities of the arm, shoulder and hand (DASH) scores at 6 months after fracture fixation. During the hardware removal surgery, which was performed at an average of 9 months (range, 8.3 to 11.5 months) after fracture fixation, we measured the PQ muscle length.

RESULTS

The average PQ muscle length was 68% of the normal muscle length, and no significant relationship was found between the PQ muscle length and the outcomes including isokinetic forearm rotation strength, grip strength, wrist range of motion, and DASH scores.

CONCLUSIONS

This study demonstrates that the length of the healed PQ muscle does not affect isokinetic forearm rotation strength and clinical outcomes after volar plating for DRFs. The results of this study support our current practice of loose repair of the PQ that is performed by most of the surgeons to prevent tendon irritation over the plate, and suggest that tight repair of the PQ is not necessary for achieving improved forearm function.

Distal radioulnar joint kinematics in simulated dorsally angulated distal radius fractures

PURPOSE

To examine the effects of dorsal angulation deformities of the distal radius with and without triangular fibrocartilage complex (TFCC) rupture on the 3-dimensional kinematics of the distal radioulnar joint (DRUJ) during simulated active motion.

METHODS

Nine fresh-frozen cadaveric specimens were tested in a forearm simulator that produced active forearm rotation. Dorsal angulation deformities of the distal radius with 10°, 20°, and 30° angulation were created. Changes in the position of the ulna relative to the radius at the DRUJ as a consequence of each dorsal angulation deformity were quantified during simulated active supination in terms of volar, ulnar, and distal displacement of the ulna. Testing was performed initially with the TFCC intact and repeated after complete sectioning of the TFCC at its ulnar insertion.

RESULTS

Increasing dorsal angulation deformities of the distal radius significantly increased volar, ulnar, and distal displacement of the ulna when the TFCC was intact. Sectioning of the TFCC significantly increased volar displacement of the ulna in dorsal angulation deformities. As little as 10° of dorsal angulation significantly increased distal displacement of the ulna with the TFCC intact and resulted in a significant increase in volar, ulnar, and distal displacement of the ulna with sectioned TFCC.

CONCLUSIONS

Dorsal angulation deformities of the distal radius affect the 3-dimensional kinematics of the DRUJ, especially with the TFCC sectioned.

CLINICAL RELEVANCE

The progressive change in DRUJ kinematics with increasing dorsal angulation may partially explain the relationship between the magnitude of dorsal angulation of distal radius fractures and functional outcomes in younger patients. The status of the TFCC should be evaluated carefully, as well as the magnitude of osseous deformity in patients with distal radius fractures and malunions, because changes in DRUJ kinematics caused by dorsal angulation are greater when the TFCC is ruptured.

Proximal ulnar stump stability after using the pronator quadratus muscle transfer combined with the Suavé-Kapandji procedure in rheumatoid wrist

The pronator quadratus muscle transfer combined with the Sauvé-Kapandji procedure was used to treat the distal radioulnar joint disorder in ten rheumatoid wrists for prevention against instability of the proximal ulnar stump. All patients were female with a mean age of 46.6 years. The mean follow-up time was 24.2 months. Postoperatively, supination increased in all patients with a mean of 50 degrees. Pain decreased significantly and none complained of prominence of the proximal ulnar stump in normal pronated position and during a tight grip. The wrist radiographs of both coronal and sagittal planes in normal and stress fisting views were used to evaluate the postoperative static and physiologic loaded stability of the proximal ulnar stump. It had shown this procedure provided good static proximal ulnar stump stability in both coronal and sagittal planes. However, in physiologic loaded condition, it was able to provide stability only in the sagittal plane.

Results of pronator quadratus repair in distal radius fractures to prevent tendon ruptures

BACKGROUND

Distal radius fractures are one of the the most common adult fractures encountered during the clinical practice of an orthopedic surgeon.12 Although several methods of treatment are suggested for these fractures, there are still controversies about the best treatment approach in the literature. Volar plating of distal radius fracture is a method of treatment which has become increasingly popular. One of the complications of this technique is flexor tendon rupture. The purpose of this study was to evaluate the protectiveness of complete repair of pronator quadratus muscle against flexor tendon rupture.

MATERIALS AND METHODS

From September 2010 to September 2012, a consecutive series of 157 patients who were younger than 60 years with unstable distal radius fractures were included in the study. A standard volar approach to the distal radius was carried out. The radial and distal ends of pronator quadratus muscle were meticulously elevated from the radius and after volar plate fixation of the fracture, pronator quadratus muscle was restored to its normal insertion. We achieved full coverage of the plate with this muscle and followed the patients postoperatively.

RESULTS

A total of 135 patients were studied. The mean age of patients was 34 ± 10 years (range 20-60 years). One 55-year-old diabetic female patient with flexor tendon rupture was identified. The flexor pollicis longus tendon had ruptured 16 months after surgery.

CONCLUSIONS

Pronator quadratus repair should be done in distal radius fracture to protect flexor tendons.

Biomechanical study of the extensor carpi ulnaris as a dynamic wrist stabilizer

PURPOSE

To investigate the dynamic stabilizing effect of the extensor carpi ulnaris (ECU) on the distal radioulnar joint (DRUJ) and the ulnocarpal joint in a simulated model of triangular fibrocartilage complex (TFCC) injury.

METHODS

Using 8 fresh-frozen cadavers, we fixed the humerus and ulna at 90° of elbow flexion, and the radius and hand were allowed to rotate freely around the ulna. Passive mobility was tested by translating the radiocarpal unit relative to the ulna along dorsal-palmar directions. Unit displacement was measured by an electromagnetic tracking device in different forearm rotations and under varied loading to the wrist motor tendons. Magnitudes of displacement were compared between different loading patterns of the prime wrist movers in the TFCC-sectioned wrists. The effect of sectioning the ECU subsheath was analyzed.

RESULTS

When physiological loads were applied to all of the prime wrist movers, the magnitude of displacement during passive mobility testing decreased in supination and neutral rotation. After ECU tendon loading was released, mobility increased again in supination and neutral rotation. When the load was applied only to the ECU tendon, mobility decreased in supination and neutral rotation as compared with unloaded. Little change in the mobility was found in pronation regardless of the tendon loading pattern. After sectioning of the ECU subsheath, the stabilizing effect of the ECU decreased in neutral rotation.

CONCLUSIONS

In a neutral wrist position with complete sectioning of the TFCC, the ECU dynamically stabilized the DRUJ and the ulnocarpal joint in supination and neutral forearm rotation. The ECU subsheath assisted ECU tendon stabilization on the ulnar side of the wrist, especially in the neutral rotation.

CLINICAL RELEVANCE

Maintaining the ECU and its subsheath may reduce DRUJ instability in patients with TFCC injuries.

Assessment of pronator quadratus repair integrity following volar plate fixation for distal radius fractures: a prospective clinical cohort study

PURPOSE

To assess prospectively the integrity of pronator quadratus (PQ) muscle repair following volar plate fixation of distal radius fractures and to compare the clinical and radiographic outcomes of durable versus failed repairs in 24 subjects. In addition, by grading the degree of PQ injury, an attempt was made to correlate failure of repair with the PQ injury severity.

METHODS

The extent of PQ injury was graded for each fracture. After fracture fixation, the PQ muscle was repaired along its radial and distal borders. Radiopaque hemoclips were attached to each side of the PQ repair, 2 radially and 2 distally. The distance between these markers at time 0 versus x-rays taken at approximately 2 weeks, 6 weeks, and 3 months was recorded. Clip displacement of 1 cm or more compared to time 0 indicated repair failure.

RESULTS

One of 24 repairs (4%) failed at 3 months. No statistical difference was noted between the type of PQ injury and wrist flexion/extension, pronation/supination, and grip strength.

CONCLUSIONS

Pronator quadratus repairs after volar plate fracture fixation are generally durable. They withstand forces that occur at the distal radius during the healing process with a 4% failure rate. No correlation was shown between type of PQ injury and radiographic failure of the repair.

Is sparing the pronator quadratus muscle possible in volar plating of the distal radius?

We measured the length of the distal radius that can be exposed by mobilizing the distal edge of pronator quadratus (PQ) without detaching its radial attachment. Measurements were made in 20 cadaveric upper limbs from the distal margin of the radius in line with the scaphoid and lunate fossae to the distal margin of the PQ, before and after mobilization of the muscle from its distal attachment. The mean distance from the distal edge of the PQ to the scaphoid fossa was 13.1 mm and to the lunate fossa was 10.7 mm. This increased to a mean of 26.2 mm for the scaphoid and a mean of 23.8 mm for the lunate fossa following mobilization of PQ. Subperiosteal retrograde release of the PQ from its distal margin will allow for the placement of a volar plate and insertion of locking peri-articular screws in the great majority of volar locking plate systems on the market.

The effect of multiplanar distal radius fractures on forearm rotation: in vitro biomechanical study

PURPOSE

Many patients develop distal radioulnar joint (DRUJ) pain and loss of forearm rotation after distal radial fractures. Residual distal radial deformity is one potential cause of DRUJ dysfunction; however, the parameters of distal radial fracture alignment that lead to an acceptable functional outcome are poorly defined in the literature.

METHODS

We used 8 fresh-frozen cadaveric specimens in this in vitro study to examine the effect of simulated distal radius fracture misalignment on forearm rotation. A distal radial osteotomy was performed just proximal to the DRUJ and a custom-made, 3-degrees-of-freedom modular implant designed to simulate distal radius fracture deformities was secured in place. This allowed for accurate simulation of dorsal angulation, dorsal translation, and radial shortening, both independently and in combination. We examined the effects of distal radius deformity in the setting of both an intact and sectioned triangular fibrocartilage complex.

RESULTS

Pronation was not significantly affected until dorsal angulation reached 30 degrees . Dorsal translation of up to 10 mm or radial shortening up to 5 mm had no effect on forearm rotation. Combined deformities had a greater effect on forearm motion than isolated malpositions. Dorsal angulation of > or =20 degrees combined with 10 mm of dorsal translation or 20 degrees of angulation with 2.5 mm of radial shortening resulted in a significant decrease in forearm pronation. There was no effect of distal radial deformities, either isolated or combined, on the magnitude of forearm rotation after sectioning the triangular fibrocartilage complex.

CONCLUSIONS

This study demonstrates that a broad range of distal radius fracture malpositions can be tolerated before a notable loss in forearm range of motion is evident. Combined deformities are more likely to result in a clinically important loss of forearm rotation, and this should be considered when choosing the optimal management of patients with displaced distal radial fractures. Disruption of the triangular fibrocartilage releases the tether on the DRUJ, allowing for preservation of forearm motion even in the setting of marked osseous deformities.

Corrective osteotomy for volar instability of the distal radioulnar Joint associated with radial shaft malunion

Volar instability of the distal radioulnar joint is an uncommon wrist disorder. We report three cases of recurrent volar instability of the distal radioulnar joint secondary to fracture of the radial shaft. In all cases, X-rays showed a volar apex deformity of the radial shaft. Opening wedge osteotomy and iliac bone grafting was performed on the distal diaphysis of the radius instead of on the radial shaft, in order to adjust the distal radioulnar joint more easily. Pre-operative dislocations and painful clunks disappeared in all three patients. However, slight instability of the distal radioulnar joint remained in all cases. Osteoarthritis of the distal radioulnar joint was noted in one patient 31 months after the operation. All of the patients were satisfied with the results and did not desire further operations.

Effect of simulated muscle activity on distal radioulnar joint loading in vitro

This study investigated the relationship between simulated forearm muscle loads and the joint reaction force in the distal radioulnar joint using an in vitro model. Seven fresh frozen cadaveric specimens were mounted in an upper extremity joint simulator capable of applying pneumatic loads to various (muscle) tendons while restraining the forearm in the three positions of pronation, supination, and neutral rotation. Loads were applied to model four forearm muscles (biceps, pronator teres, pronator quadratus, and supinator) in 10 N increments ranging from 10 N to 80 N for the biceps and pronator teres and in 10 N increments from 10 N to 50 N for the pronator quadratus and the supinator. Distal ulnar arthroplasty was performed on each specimen with a custom instrumented ulnar head replacement implant that quantified loads (via strain gauge instrumentation). The relationship between increasing muscle load and joint load was found to be positive and quasilinear in most cases. The biceps had the greatest influence on the distal radioulnar joint reaction force with a joint force in the range of 8% to 33% of the applied muscle load. The pronator teres, supinator, and pronator quadratus were less influential with a joint reaction force ranging between 6% to 19%, 4% to 9% and 2% to 10% of the applied muscle load, respectively.

Design and implementation of an instrumented ulnar head prosthesis to measure loads in vitro

The development of a novel instrumented implant for ulnar head replacement is presented in this study. This implant was instrumented with strain gauges to quantify bending moments about the anatomic axes of the distal ulna, and subsequently the distal radioulnar joint (DRUJ) reaction force magnitude. The implant was surgically inserted in seven cadaveric upper extremities, which were subsequently mounted in a custom joint simulator. Simulated active unresisted pronation and supination motion trials were conducted using computer-controlled pneumatic actuators to simulate forearm musculature. Passive (unloaded) trials were also conducted. The reaction force across the DRUJ ranged from 2 to 10 N in magnitude during this unresisted motion. Increased bending moment magnitudes were measured when the forearm was positioned in supination compared to pronation. The magnitude of joint bending moments showed a consistent pattern with forearm position, regardless of simulated active or passive rotation, or supination and pronation motion trials. This result illustrates that the primary influence on joint load is likely the position and contact with the radial articulation. This study of DRUJ loading should be useful for biomechanical modeling, implant design considerations and improved knowledge of articular mechanics.

Comparison of distal radioulnar joint reconstructions using an active joint motion simulator

PURPOSE

Distal radioulnar joint (DRUJ) instability can result in pain and functional disability. Numerous DRUJ reconstructive options have been described with minimal biomechanical analysis. The purpose of this study was to evaluate the ability of 4 well-described DRUJ reconstructions to restore joint kinematics using a dynamic, motion-controlled simulator.

METHODS

Eleven cadaveric upper extremities had computer-controlled simulated active forearm rotation. Joint kinematics were quantified by using an electromagnetic tracking system. We compared the passive and simulated active kinematics of the intact, unstable, and reconstructed DRUJ (capsular repair, 2 described radioulnar ligament reconstructions, and a radioulnar tethering procedure).

RESULTS

All reconstructions improved significantly the kinematics of the unstable DRUJ. The capsule repair restored simulated active joint kinematics closest to the intact DRUJ.

CONCLUSIONS

All 4 reconstructions improved DRUJ stability significantly. The capsule repair most closely matched intact DRUJ kinematics and the radioulnar ligament reconstructions were found to be superior to a radioulnar tethering procedure.

Soft-tissue stabilizers of the distal radioulnar joint: an in vitro kinematic study

PURPOSE

Distal radioulnar joint (DRUJ) stability is dependent on osseous anatomy, soft-tissue stabilizers, and muscle activity. The relative importance of DRUJ soft-tissue stabilizers remains controversial and has not been examined in the more physiologic setting of simulated muscle loading in the intact specimen. The purpose of this study was to examine the role of static stabilizers on the kinematics of the DRUJ during active simulated motion.

METHODS

Twelve cadaveric upper extremities underwent computer-controlled, simulated, active forearm rotation. Joint kinematics were measured in the intact specimen and after sequential sectioning of soft-tissue stabilizers including the dorsal and palmar radioulnar ligaments (RULs) and the triangular fibrocartilage (TFC), dorsal and palmar capsule, ulnocarpal ligaments (UCL), extensor carpi ulnaris (ECU) subsheath, pronator quadratus (PQ), and the interosseous membrane (IOM).

RESULTS

After sectioning of soft tissues significant changes in the DRUJ kinematics were observed. With a distal to proximal sectioning sequence significant alterations in kinematics were not identified until sectioning of the IOM; with a proximal to distal sectioning sequence intact DRUJ kinematics were maintained until the final soft-tissue (RULs and TFC) sectioning.

CONCLUSIONS

Sectioning of all soft-tissue stabilizers produced significant DRUJ instability and abnormal joint kinematics. The RULs and TFC play a key role in DRUJ kinematics because they can help to maintain normal joint rotation in the absence of all other soft-tissue stabilizers. With the preservation of other soft-tissue stabilizers, however, the RULs and TFC are not essential for the maintenance of normal kinematics of the DRUJ.