Distal Radioulnar Joint Instability

Aromatase Inhibitor-Associated Distal Radioulnar Joint Instability and Tear of the Extensor Digiti Minimi: A Case Report

ABSTRACT

The addition of aromatase inhibitors has improved cancer-related outcomes in postmenopausal patients with estrogen receptor-positive breast cancer. However, aromatase inhibitor can be associated with a constellation of adverse musculoskeletal effects that comprises bone loss, arthralgia, myalgia, and tendinopathy. This medication complication, known as aromatase inhibitor-associated musculoskeletal syndrome, can limit treatment tolerability in many patients because of the high prevalence of aromatase inhibitor-associated musculoskeletal syndrome among those on aromatase inhibitor. The hand and wrist are the most affected joints in aromatase inhibitor-associated musculoskeletal syndrome, with patients presenting with symmetric arthralgia, stiffness, and tendinopathy. Radioulnar joint subluxation with extensor tendon tear has not been previously reported in patients with aromatase inhibitor-associated musculoskeletal syndrome. This is a case report of a 72-yr-old breast cancer survivor on an aromatase inhibitor presenting with chronic dominant wrist pain, weakness, and 5th digit finger drop. An extensor digitorum minimi tendon tear and radioulnar instability were identified using diagnostic musculoskeletal ultrasonography. This case illustrates the utility of in-office ultrasonography combined with dynamic examination for the often underrecognized pathology associated with aromatase inhibitor-associated musculoskeletal syndrome in breast cancer survivors.

[Concomitant injuries of the wrist, distal ulna and distal radioulnar joint in distal radius fractures : Primary operative cotreatment vs. healing with no additional treatment]

Distal radius fractures are the most common fractures in adults and account for one quarter of all fractures, with increasing incidence. The number of patients and the requirement of an exact treatment are high. Continuous developments in diagnostic and operative possibilities enable in many cases a high-quality treatment with good clinical outcome; however, radius fractures rarely occur alone but in combination with additional fractures or ligamentous injuries. The frequency and extent of these injuries are not linked to the complexity of the primary injury. The aim is to recognize and correctly diagnose potential concomitant injuries. Many injuries do not need immediate treatment but heal without additional treatment after the radius has been treated. It is important to recognize those injuries which can cause severe complications if untreated; however, exactly this is often difficult. In many cases there is still no consensus if and how concomitant injuries should be treated. This article highlights the most frequent concomitant injuries in distal radius fractures with the possible advantages and disadvantages of cotreatment in order to facilitate decision making.

Isolated Volar Radioulnar Joint Dislocation With Associated Ulnar Styloid Fracture

Isolated volar dislocation of the distal radioulnar joint is a rare occurrence and is commonly missed. The mechanism of injury typically involves hypersupination. True lateral radiographs are difficult to obtain as patients are usually limited with wrist pronation and supination, resulting in a high miss rate. We describe a 32-year-old male who presented to the emergency department (ED) with pain and swelling of the posteromedial aspect of the right wrist after punching a wall one hour prior to presentation. Examination revealed soft tissue tenderness and mild edema at the right distal ulna with an associated deformity, best visualized at the volar aspect of the right wrist. Active range of motion was limited with right wrist flexion and extension, secondary to pain and edema. Right wrist supination and pronation strength and range of motion were limited due to the patient's tenderness on examination. Peripheral nerve function and vascular examination were normal. Initial radiographs of the right hand, wrist, and forearm did not reveal a fracture or dislocation. A musculoskeletal computed tomography (CT) scan of the right hand and wrist revealed an avulsion fracture of the ulnar styloid with volar displacement of the ulna. Analgesia was achieved with an ultrasound-guided ulnar nerve block, and the right wrist was successfully reduced. This report highlights the difficulty in obtaining a diagnosis of an isolated volar dislocation of the distal radioulnar joint. We recommend obtaining a musculoskeletal CT scan in the setting of an inconclusive radiograph and incongruent physical examination. Analgesia can also be achieved with an ulnar nerve block under ultrasound guidance.

Distal oblique bundle influence on distal radioulnar joint stability: a biomechanical study

Chronic instability of the distal radioulnar joint (DRUJ) presents a highly disabling condition. Several surgical techniques have been reported for its treatment. These involve reconstruction of the distal oblique bundle (DOB) of the interosseous membrane (IOM) of the forearm. The aim of this study was to examine whether surgical reconstruction of the DOB is necessary to restore DRUJ stability following trauma with DOB disruption and to compare two restoration techniques utilizing a tendon or suture-button graft. Stability in supination and pronation was assessed by means of maximum torque and force in twenty forearms. Test cycles were performed with the DOB/IOM in an intact condition, with the DOB or distal IOM transected, and following surgical reconstruction of the DOB with either tendon graft or suture-button system. In pronation, the relative change in maximum axial force was significantly lower in samples with a transected DOB in comparison to samples without a preexisting DOB. No statistically significant differences were observed between forearms including DOB reconstruction and specimens in the intact and transected state. Neither were there statistically significant differences concerning the two surgical techniques. From a biomechanical perspective, surgical DOB reconstruction is hence not indicated in cases of isolated DOB rupture.

Arthrex Mini Tightrope Fixation for Chronic Distal Radioulnar Joint Instability

Chronic distal radioulnar joint (DRUJ) instability is a complex clinical condition that is difficult to treat. Currently, there is no gold standard treatment. We present a novel technique using Arthrex Mini Tightrope for DRUJ stabilization. In this case series, a 1.6 mm K-wire was passed transversely through the distal ulna and radius. The Mini Tightrope was inserted into the end of the K-wire and pulled through the bone tunnels. Appropriate tension was achieved to stabilize the joint according to individual laxity comparable to the contralateral side. Five patients (3 males and 2 females) comprised this pilot series, with a mean age of 27.1 years. All sustained a traumatic injury at an average of 12.4 months before surgery (range: 5 to 32 mo). In addition, 3 patients had central triangular fibrocartilage complex tears treated with arthroscopy at the time of Mini Tightrope placement. While one patient was lost to follow-up after 7 weeks postoperative due to incarceration, 4 patients demonstrated coronal and sagittal stability in the context of DRUJ motion and a satisfactory range of motion. The mean time for the return to work for the two patients who were laborers or normal activity postoperatively was 5.2 weeks (range: 1 to 16.4 wk). Unrestricted activity was generally allowed 8 weeks postoperatively but varied by patient. The same 4 patients underwent hardware removal at an average of 31 weeks (range: 15 to 44 wk). Although this is only a pilot series, this suggests that temporary Mini Tightrope stabilization of the DRUJ may be a viable solution while upholding the benefits of minimally invasive surgery.

Ligament reconstruction with modified suture anchor fixation technique for chronic distal radioulnar joint instability: A case report and literature review

INTRODUCTION

The chronic instability of the DRUJ should be appropriately treated. Ligament reconstruction in the original technique needs an adequate length of the graft, which needs to be modified in such a case.

CASE PRESENTATION

A 27-year-old male presented with right wrist pain accompanied by limited movement that has been felt for the last two months. There was an obvious deformity with tenderness. Palpation revealed a positive ballottement and piano-key sign test. An X-ray examination revealed a union fracture one-third distally on the right radius bone with dorsal dislocation of the right distal radioulnar joint. The result of an MRI confirmed a triangular fibrocartilage complex tear. The patient was diagnosed with chronic DRUJ instability.

DISCUSSION

We performed a chronic DRUJ reconstruction using the harvesting palmaris longus tendon. However, the length of the graft is too short. Further, we performed a modified technique with suture anchor fixation for this patient. This technique could be a helpful alternative if the length of the graft is insufficient. As a result, there was an improvement in the DASH score and EQ5D questionnaires.

CONCLUSION

Chronic DRUJ instability could be treated by ligament reconstruction with modified suture anchors fixation in the inadequate length of the graft situation.

Concomitant ligament injuries can be left untreated during surgery of distal radial fractures

Instability of the distal radioulnar joint and scapholunate dissociation may cause pain, functional impairment and subsequent arthrosis. There is no consensus about whether these injuries should be treated acutely in patients undergoing surgery for distal radial fractures. We conducted a prospective cohort study to determine whether concomitant distal radioulnar joint instability or scapholunate dissociation negatively influence patient-related outcomes in these patients. The primary outcome was the patient-reported wrist/hand evaluation at 6 and 12 months after surgery. Out of 62 patients, 58% and 27% had intraoperative distal radioulnar joint instability and scapholunate dissociation, respectively. No significant differences were found in patient-reported scores at follow-up between patients with stable and unstable distal radioulnar joints, nor between patients with and without scapholunate dissociation. Sixty-three per cent of patients with an unstable distal radioulnar joint during surgery were stable on retesting after 6 months. Our study suggests that a wait-and-see policy in these patients therefore seems reasonable.Level of evidence: III.

Radioulnar Instability and Ulnar Stump Stabilization in Distal Radio Ulnar Joint Arthritis: A Cadaver Study

BACKGROUND

Salvage procedures for distal radioulnar joint (DRUJ) arthritis, like the Darrach or Sauvé-Kapandji (S-K) procedures, often result in extensor tendon ruptures at the ulnar stump. Radioulnar instability is considered the underlying cause and stump stabilization techniques are employed. This study investigated radioulnar instability, extensor tendon irritation, and the effectiveness of stump stabilization techniques following salvage procedures.

METHODS

Six upper limbs from three cadavers were used. Forearm rotation was measured using magnetic position sensors to assess radial movement. The Darrach procedure was performed on two limbs, comparing radial motion ranges for different ulnar osteotomy positions. The risk of tendon rupture was assessed with applied weight. The S-K procedure was performed on four limbs, evaluating stump stabilization techniques and radial movement distance underweight.

RESULTS

Proximal osteotomy positions increased radial motion range. Extensor tendon irritation occurred when the load was applied to the volar and ulnar sides, particularly with a pronated forearm. Stump stabilization techniques did not significantly contribute to ulnar stump stabilization.

CONCLUSIONS

Proximal ulnar osteotomy positions in DRUJ salvage procedures led to increased radioulnar instability and potential complications. Load application on the volar and ulnar sides, especially in a pronated forearm, increased the risk of tendon rupture. Stump stabilization techniques showed limited utility in stabilizing the ulnar stump or reducing complications. These findings can inform strategies for minimizing complications in DRUJ salvage procedures.

Kinematic analysis of forearm rotation using four-dimensional computed tomography

This study aimed to quantify forearm kinematics with a focus on the forearm rotation axis. Ten healthy volunteers were included in the study. One three-dimensional computed tomographic scan and two four-dimensional computed tomographic scans were done in all the arms to capture forearm joint motion. After image processing, the rotation axis and the movement of the radius with respect to various axes were quantified. The rotation axis was calculated using finite helical axis analysis and a circle fitting approach. The mean error of the rotation axis found through circle fitting was 0.2 mm (SD 0.1) distally and 0.1 mm (SD 0.1) proximally, indicating an improvement in precision over the finite helical axis approach. The translations of the radius along the ulnar axis and the forearm rotation axis were 2.6 (SD 0.8) and 0.6 mm (SD 0.9), respectively. The rotation of the radius around the radial axis was 7.2°. The techniques presented provide a detailed description of forearm kinematics.

Ulnar shortening osteotomy for posttraumatic ulnar impaction syndrome in adolescent (younger than 18 years) - Based on the Cha & Shin assessment

PURPOSE

We performed ordinary ulnar shortening osteotomy (USO) in patients younger than 18 years old with secondary ulnar impaction syndrome (UIS) after traumatic events. Here, we report the clinical and radiologic outcomes with a review of the previous literature through a retrospective case series.

METHODS

Twenty-two adolescents treated by USOs from 2006 to 2018 were investigated. The amount of shortening was classified into three categories. The first category was for a still open physis on the medial half of the radius in those younger than 15. In this category, we osteotomized the ulna for the physis level to be left neutral or negative by 1-2 mm. The second category had no growth potency in the radius. If the patient was younger than 15, we considered only residual growth of the ulna, thus performing USO for the ordinary UV to be negative by 2-3 mm. For patients aged 15-18 years old, if growth potency was nearly absent in the ulna, we performed traditional USO with a neutral ulnar variance (UV).

RESULTS

Categories 1, 2, and 3 for the amount of USO were determined for 4, 4, and 14 patients, respectively. All USOs properly healed without substantial complications. The mean preoperative UV was 2.91 mm, and the final value decreased to 0.23 with statistical significance (p < 0.001). The range of wrist motion was improved after USO from 133.86° and 132.73° to 154.77° and 160.68° (all, p < 0.001 in flexion-extension and pronation-supination arcs, respectively). The preoperative VAS and MMWS scores also improved from 2.77 to 75.00 to 0.18 and 88.86, respectively, at the final follow-up (all, p < 0.001).

CONCLUSIONS

UIS in adolescent populations after trauma in their children/younger adolescents could be properly treated by USO. Even with an open physis at the ulna, neutral UVs could be achieved, and the clinical outcomes were satisfactory. However, long-term follow-up is still needed regarding TFCC and DRUJ status.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

Comparative Study of 2 Bone Anchors Using a Limited Open Procedure for the Management of Distal Radioulnar Joint Instability

BACKGROUND

Arthroscopic and open surgical procedures are commonly used to repair distal radioulnar joint (DRUJ) instability. Both may result in patient dissatisfaction and recurrence of DRUJ instability. An alternative treatment that yields improved outcomes is a limited open approach using a bone anchor to support the DRUJ.

METHODS

A retrospective chart review of 58 patients (59 extremities) aged 18 to 60 years with type 1B Palmer rupture (3 months or more after injury) of the triangular fibrocartilage complex (TFCC) without distal radius fracture was conducted. Inclusion criteria are: 3 to 12 months after injury, clinical DRUJ instability, and minimum of 6 months of postoperative follow-up. Operative fixation with Stryker Sonic or Depuy Mitek anchor was done by the same surgeon using a limited open procedure. Preoperative and postoperative assessments included Disability of the Arm, Shoulder, and Hand; Brief Pain Inventory; Wong-Baker FACES Pain Rating Scale; Numeric Pain Scale; range of motion; and recurrence of instability. A multivariate analysis of variance model was fit to imputed data to assess the effect of both anchors.

RESULTS

Clinical and statistical differences were found in preoperative and postoperative assessments for either the Stryker Sonic or the Depuy Mitek anchor but not between anchor types. There was no recurrence after 3 years with either anchor.

CONCLUSION

Patients requiring TFCC repair using the Stryker Sonic or Depuy Mitek anchor experienced: (1) significant clinical and statistical improvement in postoperative assessments; (2) patient satisfaction; and (3) corrected DRUJ instability. Consequently, major determinants in deciding which bone anchor to use may be based on cost or surgeon's preference.

Wrist weight-bearing tolerance in healthy adults

STUDY DESIGN

Cross-sectional.

INTRODUCTION

No information is available in the literature regarding the amount of weight-bearing tolerance in a normal human wrist.

PURPOSE OF THE STUDY

To establish the normal limits of human wrist weight-bearing tolerance and to determine if gender, age and height are predictors of this weight-bearing tolerance.

METHODS

A sample (N = 465) of healthy adults ages 18-64 completed a questionnaire indicating their gender, age range and height. Subjects were instructed in performing a wrist weight-bearing tolerance test using a calibrated analog scale. The amount of pressure that the subject was able to apply to the scale in 3 independent trials was recorded and analyzed.

RESULTS

A strong positive correlation was found between average weight- bearing values achieved through the right and left hands for the subjects of this study, r(463)= .97, P < .001. A 2-way analysis of covariance revealed main effects for both gender (20.9, 95% CI [15.7, 26.0] pounds, P < .001) and age (F(4, 454) = 6.143, P < .001, partial η² = .051). The highest weight-bearing tolerance was observed in males and individuals 25-34 years of age. Multiple regression analysis affirmed that gender, height and age categories of 45-54 and 55 to 64 were all statistically significant predictors of wrist weight-bearing tolerance, P < .01.

DISCUSSION

These results establish normal wrist weight-bearing tolerance values and demonstrate that gender, age and height are predictors of this weight-bearing tolerance.

CONCLUSION

These results could allow identification of pathologies associated with wrist instability.

Rehabilitation in Triangular Fibrocartilage Complex Injuries: Treatment Algorithm

Injuries to the triangular fibrocartilage complex (TFCC) can lead to instability of the distal radioulnar joint (DRUJ). In fact, they are the most frequent cause of it. But, in other cases, depending on the type of injury, the DRUJ remains stable. This will condition different types of treatments, from conservative management to the different options of surgical treatment. Since a controversy persists regarding the management of these lesions, our purpose is to disclose the foundations of the rehabilitation treatment and propose an algorithm of treatment according to the different types of injuries and their repairs.

Application of Suspension Fixation with Button Plates for Patients with Distal Radioulnar Joint Dislocation: A Case Series

Objective

The aim of the present study was to assess the effect of suspension fixation with button plates on the reconstruction of the distal radioulnar joint dislocation (DRUJ).

Methods

This was a case series of six patients (two men and four women) who underwent suspension fixation with button plates for DRUJ dislocation between January 2015 and May 2017. Physical examination, radiography, MRI, functional activity of the wrist joint, grip strength of the wrist joint, Garland–Werley wrist score, Mayo wrist score, and visual analog scale (VAS) score were used to evaluate the effect of this procedure. All patients were followed up every 3 months. The evaluation time point was 12 months after the operation. Comparisons of the functional indexes of wrist function before and after the operation were performed using paired statistical tests.

Results

The mean range of motion of the affected limb was 70° at forearm pronation and 75° at forearm supination. The subjective assessments and tests of the motor function of the wrist showed improvement after surgery. The Garland–Werley wrist score was 13.50 ± 2.66 preoperatively, the Mayo wrist score was 56.67 ± 18.35, and the VAS score was 4.83 ± 1.17. The Garland–Werley wrist score was 2.83 ± 1.33 postoperatively at 12 months, the Mayo wrist score was 87.5 ± 6.89, and the VAS score was 0.50 ± 0.55. At 12 months, the Garland–Werley wrist score, the Mayo wrist score, and the VAS score showed significant improvements when compared with those before surgery (P = 0.000, P = 0.003, and P = 0.000, respectively). Radiographic examination revealed that the internal fixation device was in place, and no dislocation of the DRUJ could be observed. None of the patients had internal fixation device removal or re‐dislocation of the DRUJ. None of the patients had re‐dislocation of the DRUJ. No secondary ulnar or radial fractures and nerve injury were reported during and after surgery. No tumor recurrence was observed in patients with giant cell tumors of the tendon sheath. No loosening and displacement of screws were reported.

Conclusion

The new method of suspension fixation with button plates for the surgical reconstruction of a DRUJ dislocation is simple, with minimal trauma, and maintains the stability of the DRUJ without the need for intra‐articular or extra‐articular reconstruction of the ligament. Furthermore, it allows early functional exercise and achieves satisfactory postoperative functional recovery.

Management of Acute Distal Radioulnar Joint Instability Following a Distal Radius Fracture: A Systematic Review and Meta-Analysis

Purpose

We sought to review the clinical outcomes of conservative and operative treatment options for acute distal radioulnar joint (DRUJ) instability associated with distal radius fractures in adult patients.

Methods

A systematic search of PubMed, MEDLINE, and EMBASE for articles published between 1990 and 2020 involving DRUJ instability associated with distal radius fractures was performed. The primary outcomes analyzed included clinical grip strength; range of motion; the disability of the arm, shoulder and hand (DASH) score; and the modified Mayo wrist score (MMWS).

Results

Of the 531 articles identified in the literature search, 8 met our defined criteria and were included in the final analysis. The cumulative sample size was 258 patients at a mean follow-up of 11.1 months (range, 3–16.9 months). Treatment groups included cast immobilization in supination, K-wire stabilization, and triangular fibrocartilage complex (TFCC) repair. Statistical analysis revealed no difference across groups in active flexion-extension or DASH scores. A significant decrease in grip strength was found in patients who underwent TFCC repair compared with that in those who underwent both cast immobilization (P = .04) and K-wire stabilization (P = .02). Furthermore, we found a significant decrease in active pronation-supination between patients who underwent TFCC repair and those who underwent cast immobilization (P = .03). Patients who underwent TFCC repair were also found to exhibit decreased MMWS as compared with those who underwent K-wire stabilization (P = .05). Overall, persistent DRUJ instability was only found in 4 patients (1.5%), without a significant difference between treatment groups.

Conclusions

This study suggests functional advantages of certain treatment modalities over others, with the range of motion being highest in patients who underwent cast immobilization and grip strength being highest in patients who underwent K-wire stabilization. However, the mean DASH scores showed no difference across all groups, calling into question the clinical need to pursue operative treatment via K-wire stabilization or TFCC repair over conservative treatment via cast immobilization. This study will hopefully serve as a foundation for future prospective studies to help improve and standardize treatment algorithms in patients with DRUJ instability and distal radius fractures.

Type of study/level of evidence: Therapeutic II.

Evaluation and Management of Hand, Wrist and Elbow Injuries in Ice Hockey

Ice hockey continues to be a popular, fast-paced, contact sport enjoyed internationally. Due to the physicality of the game, players are at a higher risk of injury. In the 2010 Winter Olympics, men’s ice hockey had the highest injury rate compared to any other sport. In this review, we present a comprehensive analysis of evaluation and management strategies of common hand, wrist, and elbow injuries in ice hockey players. Future reseach focusing on the incidence and outcomes of these hand, wrist and elbow injuries in ice hockey players is warranted.

Technique of Tendon Interposition Arthroplasty for Chronic Volar Dislocation of the Distal Radioulnar Joint

Volar distal radioulnar joint (DRUJ) dislocations are uncommon wrist injuries. Failed diagnosis or treatment can result in irreversible damage to the articulating surfaces and ultimately lead to chronic degenerative arthritis. When the DRUJ is reducible, and the cartilage is preserved, ligament reconstruction and ulnar osteotomy are surgical options for residual wrist instability or pain. When destruction of the native DRUJ has already occurred, surgical treatment options are salvage procedures. Here we present treatment for a chronic volarly dislocated DRUJ with open reduction and internal fixation using an alternative joint-preserving surgical technique with tendon allograft interposition arthroplasty.

Modified Sauve-Kapandji Procedure for Patients with Old Fractures of the Distal Radius

Objective

To evaluate the clinical and radiographic outcomes of a modified Sauve-Kapandji procedure for patients with old fractures in the distal radius.

Methods

Fifteen patients (10 male and 5 female patients with an average age of 40 years old) were treated by the modified Sauve-Kapandji procedure from January 2014 to April 2016. All patients had undergone at least one previous operation on the involved wrist, and they were still suffering from pain and functional limitations at the time of admission. The postoperative follow-up period was 12-26 months and the average was 20 months. Functional assessment was made at the last follow-up. All patients were evaluated according a Modified Mayo Wrist Score system.

Results

Of the fifteen patients with posttraumatic arthritis, thirteen had excellent results, two had good results, and one had fair results. There were no major complications.

Conclusions

The modified Sauve-Kapandji procedure is a safe and effective surgical alternative for intractable disorders of the distal radioulnar joint and can be recommended as a salvage procedure when previous treatments fail.

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 prospective study of a modified pin-in-plaster technique for treatment of fractures of the distal radius

Objectives

There are various pin-in-plaster methods for treating fractures of the distal radius. The purpose of this study is to introduce a modified technique of ‘pin in plaster’.

Methods

Fifty-four patients with fractures of the distal radius were followed for one year post-operatively. Patients were excluded if they had type B fractures according to AO classification, multiple injuries or pathological fractures, and were treated more than seven days after injury. Range of movement and functional results were evaluated at three and six months and one and two years post-operatively. Radiographic parameters including radial inclination, tilt, and height, were measured pre- and post-operatively.

Results

The average radial tilt was 10.6° of volar flexion and radial height was 10.2 mm at the sixth month post-operatively. Three cases of pin tract infection were recorded, all of which were treated successfully with oral antibiotics. There were no cases of pin loosening. A total of 73 patients underwent surgery, and three cases of radial nerve irritation were recorded at the time of cast removal. All radial nerve palsies resolved at the six-month follow-up. There were no cases of median nerve compression or carpal tunnel syndrome, and no cases of tendon injury.

Conclusion

Our modified technique is effective to restore anatomic congruity and maintain reduction in fractures of the distal radius.

Cite this article: Bone Joint Res 2015;4:176–180