Landmarks for rotational alignment of the humeral component during elbow arthroplasty

An Automatic Method for Elbow Joint Recognition, Segmentation and Reconstruction

Elbow computerized tomography (CT) scans have been widely applied for describing elbow morphology. To enhance the objectivity and efficiency of clinical diagnosis, an automatic method to recognize, segment, and reconstruct elbow joint bones is proposed in this study. The method involves three steps: initially, the humerus, ulna, and radius are automatically recognized based on the anatomical features of the elbow joint, and the prompt boxes are generated. Subsequently, elbow MedSAM is obtained through transfer learning, which accurately segments the CT images by integrating the prompt boxes. After that, hole-filling and object reclassification steps are executed to refine the mask. Finally, three-dimensional (3D) reconstruction is conducted seamlessly using the marching cube algorithm. To validate the reliability and accuracy of the method, the images were compared to the masks labeled by senior surgeons. Quantitative evaluation of segmentation results revealed median intersection over union (IoU) values of 0.963, 0.959, and 0.950 for the humerus, ulna, and radius, respectively. Additionally, the reconstructed surface errors were measured at 1.127, 1.523, and 2.062 mm, respectively. Consequently, the automatic elbow reconstruction method demonstrates promising capabilities in clinical diagnosis, preoperative planning, and intraoperative navigation for elbow joint diseases.

Reliability of the Sigmoid Notch Classification of the Distal Radioulnar Joint

Background  The Tolat sigmoid notch classification is a commonly used classification to characterize the distal radioulnar joint (DRUJ). This classification was based on a limited assessment of the entire joint, which may lead to inaccuracies in sigmoid notch evaluation. Questions/Purposes  The purpose of this study is to assess the reliability of the Tolat classification for sigmoid notch characterization. Methods  The sigmoid notch of 52 models of cadaveric forearms was assessed by applying the Tolat classification to the three-dimensional (3D) modeled notch and then slices at the start of the notch (0 mm) and 4 mm more proximal. The inter- and intrarater agreement was assessed using Cohen's and Fleiss' kappa statistic. Results  Agreement between iterations regardless of slices or surgeons/radiologists was moderate. Intrarater agreement between pairs of slices (0 vs 4 mm, 0 mm vs 3D, 4 mm vs 3D) was moderate, whereas agreement between all slices was slight. Agreement between surgeons and between radiologists was moderate, while agreement across all raters and slices was fair. Models described as "other" were more consistent in 3D classifications and were commonly classified as a reverse ski slope. Conclusions  Classification using the Tolat scheme is fair to moderate at best. Classification of the sigmoid notch using an axial view of the distal radius may not accurately reflect the anatomy throughout the notch. Clinical Relevance  The Tolat classification supplies a limited analysis of the sigmoid notch, and does not represent a comprehensive evaluation of the entire joint. Future classification systems should characterize the entire sigmoid notch.

A Soft-Tissue Landmark to Assess Humeral Component Rotation in Total Elbow Arthroplasty

HYPOTHESIS

Assessing the rotational alignment of the humeral component during total elbow arthroplasty is dependent upon bony landmarks that can be absent or altered in cases of distal humerus fractures, revision arthroplasty, severe bone loss, or deformity. We hypothesize that the intermuscular septum can be used as a reliable soft-tissue landmark to set the rotation of the humeral component intra-operatively when previously described bony landmarks are not reliable or present.

MATERIALS AND METHODS

Forty-eight unpaired cadaveric human subjects (mean age and standard deviation 63 ± 12 years; 24 males, 24 females) underwent computed tomography (CT) scans. The geometric centers of the trochlea and capitellum were assessed, and the line through these two points was set as the flexion-extension axis (FEA) of the elbow. The intermuscular septum axis (IMSA) was drawn proximal to the olecranon fossa and at least 4 cm proximal to the most distal point of the articular surface, where the posterior humeral cortex was flat. The angles between the FEA and IMSA were calculated and compared using a two-tailed t-test. Regression analysis was used to assess the inter- and intra-observer reliability of the IMSA.

RESULTS

The IMSA was externally rotated 10.3° ± 2.8 compared to the FEA (p < 0.001 and confidence interval (CI) of 2.8 with α set to 0.01). The inter- and intra-observer reliability of the IMSA was high, with an R-value of 0.91 and 0.97, respectively.

CONCLUSIONS

The intermuscular septum can be used as a soft-tissue landmark to set humeral component rotation and is 10.3° externally rotated with respect to the FEA of the ulnohumeral joint.

Controversies in the Management of Bicolumnar Fractures of the Distal Humerus

Bicolumnar fractures of the distal humerus pose numerous treatment challenges for upper-extremity surgeons. Although open reduction and internal fixation demonstrates advantages compared with nonsurgical treatment, restoration of osseous anatomy can be difficult, particularly for comminuted, intra-articular fractures. Despite well-recognized complications, total elbow arthroplasty remains an option for elderly patients with fractures not amenable to fixation. Although indications remain controversial, distal humerus hemiarthroplasty has emerged as a potential alternative to total elbow arthroplasty in carefully selected patients with nonreconstructable fractures. Numerous controversies remain with respect to the management decisions for these complex injuries, including the optimal surgical approach, management of the ulnar nerve, and ideal fixation constructs for open reduction internal fixation. Our purpose is to review the management of bicolumnar distal humerus fractures in adult patients and discuss current controversies related to treatment.

Elbow arthroplasty in trauma-current concepts review

Introduction

Despite advancements in modern locking plate technology, distal humerus fractures in the elderly remain difficult to treat. A subset of fractures in this osteoporotic bone includes multiple, shallow articular fragments that renders fixation unreliable, precluding early motion and acceptable functional outcomes. Arthroplasty, in the form of either Total Elbow Arthroplasty (TEA) or Distal Humeral Hemiarthroplasty (DHH) are alternative treatment options in this cohort and are being increasingly used.

Methods

This article reviews the use of TEA or DHH for acute distal humerus fracture, including patient selection, pre-operative planning, surgical approach, implant positioning, rehabilitation, outcomes and complications.

Results

Arthroplasties are being increasingly used for acute distal humerus fractures, however they introduce potential complications not seen with fixation. Due care must be employed to correct implant positioning which is a function of implant rotation, implant length and implant sizing. We describe a robust technique for epicondyle repair in DHH and unlinked TEA to avoid instability. Outcomes of DHH and TEA for acute distal humerus fracture are encouraging, however further long-term outcome and comparative data regarding arthroplasty is required.

Conclusions

Short to medium term outcomes demonstrate that both DHH and TEA are valuable options for selected patients, although attention to technique is required to minimise potential complications.

Clinical anatomy and biomechanics of the elbow

The anatomy of the elbow joint had been studied extensively over the last 2 decades. The increased understanding of the anatomy and contribution of the anatomical structures to the elbow biomechanics had enabled surgeons to improve the results of surgical reconstruction and fracture fixation. This review articles intend to summarise the salient functional and clinical anatomical and relevant biomechanical data that had been published recently.

Current concepts in distal humeral hemiarthroplasty

Multi-fragmentary intra-articular fractures of the distal humerus remain a challenge for both patients and surgeons. Open Reduction internal fixation remains the gold standard, however in older patients with comminuted fractures this might not be feasible. There is a growing interest in hemi-arthroplasty as a solution for these cases. However the current experience and follow-up in limited. This review article intends to describe the current concepts in elbow hemiarthroplasty in dept. we will discuss the historical use of these implants, as well as the intricacies of more modern devices. Next we will elaborate an surgical planning, approach, and technical pearls. We will lay out a rehab protocol used by the senior author, and with some considerations for the future.

Primary total elbow arthroplasty

There have been significant improvements in surgical techniques and implant designs of elbow arthroplasty over the last five decades. These advances have resulted in improved outcomes and expansion of indications for total elow arthroplasty (TEA). As the proportion of TEAs being performed for inflammatory arthritis has been decreasing in recent years, TEAs are being performed more commonly for the management of acute distal humerus fractures in the elderly, post-traumatic sequelae, and primary osteoarthritis. Appropriate patient selection and meticulous attention to surgical technique including the surgical approach, implant positioning and fixation will result in acceptable outcomes. Future advances in the design, instrumentation, and surgical technique will allow for further improvement in outcomes as the indications for TEA continue to expand.

Elbow hemiarthroplasty in distal humeral fractures: Indication, surgical technique and results

The surgical management of distal humerus fractures in adults generally consists in open reduction internal fixation (ORIF) or total elbow arthroplasty (TEA). Hemi humeral hemiarthroplasty (EHA) is a treatment option for unreconstructable intra-articular distal humerus fractures. It is a reasonable option in patients over the fifth decade and its potential advantages are to eliminate the complications related to the ulnar component such as wear of the hinge (busching wear) or the aspetic loosening of the ulnar component. The potential disadvantages are the risk of instability with the possibility of a wear and progressive joint osteoarthrosis. The aims of this manuscript are to evaluate the indications in which we used the EHA, analyzing the correct surgical technique and describe the outcomes in medium and long-term follow-ups. Between 2006 and 2019, we performed 51 EHAs at the Hesperia Hospital in Modena and at the Rizzoli Orthopedic Institute. Taking into consideration only the cases of acute fractures, 27 patients (27 elbows) with a minimum follow-up of 12 months were identified. The patient's mean age at the time of surgery was 64 years old (range from 45 to 78 years old) and they were 78% female (21 out of 27). The Latitude Tornier implant was used in all the patients of our group. The mean MEPS was 89.3 points (from 50 to 100 pts) with excellent results in 19 patients, good in 5, one fair and 2 poor;the mean DASH was 12.6 (from 3.3 to 45.8); the mean OES was 42.3 (from 22 to 47). Complications, were found in 12 patients and any patients required a TEA conversion. Distal humerus hemiarthroplasty from our experience is a good option for the surgical management of unrecostructible distal humeral fractures in selected patients. It is important to perform a precise surgical technique; preserve the triceps insertion, preserve or repair the collateral ligaments, fix the condylar bones implant the prosthesis at the correct size, depth and rotation. The majority of the complication that we observed are related to the stiffness and no to the progressive degenerative changes of the articular surface.

Elbow Hemiarthroplasty for the Treatment of Distal Humerus Fractures

Distal humerus hemiarthroplasty is a good surgical option for nonreconstructable intraarticular distal humerus fractures in selected lower-demand patients. The lifetime activity restrictions have not been determined, but are likely less than a total elbow arthroplasty. From a technical standpoint, distal humeral prostheses should be implanted at the correct depth and rotation. The collateral ligaments, condyles, and epicondyles should be preserved and/or repaired to maintain joint stability. Short- to midterm retrospective studies have shown promising results.

Quantification of the articular view of the elbow afforded by standard portals using 30° arthroscopy

BACKGROUND

The present study quantifies the field of view (FOV) from standard arthroscopy portals and aims to identify anatomical regions where the FOV is limited.

METHODS

Eleven cadaveric elbows were examined through standard anteromedial, anterolateral and posterior portals. The FOV was marked with dye using a spinal needle. The articular surfaces were then exposed and the percentage FOV seen was calculated. FOV percentage areas were compared using a Student's t-test (JMP, version 10, SAS Institute Inc., Cary, NC, USA). P < 0.05 was considered statistically significant.

RESULTS

The mean (SD) FOV percentage area seen from the anteromedial portal and anterolateral portal was 91.69% (3.63%) and 92.03% (3.93%), respectively, for the anterior humerus articular surface. There was no significant difference in the mean FOV percentage area seen from the anteromedial and anterolateral portals (p = 0.99). The mean (SD) FOV percentage area of the posterior humerus articular surface was 84.69% (2.28%). The mean (SD) FOV percentage area seen of the radial head and trochlear was 16.05% (2.66%) and 4.14% (1.76%), respectively.

CONCLUSIONS

The present study is the first to quantify the FOV of elbow arthroscopy. The majority of the anterior and posterior humerus articular surface can be seen through standard portals. The limitations in FOV are primarily confined to the radial head and trochlear notch.

Accuracy in identifying the elbow rotation axis on simulated fluoroscopic images using a new anatomical landmark

External fixation of the elbow requires identification of the elbow rotation axis, but the accuracy of traditional landmarks (capitellum and trochlea) on fluoroscopy is limited. The relative distance (RD) of the humerus may be helpful as additional landmark. The first aim of this study was to determine the optimal RD that corresponds to an on-axis lateral image of the elbow. The second aim was to assess whether the use of the optimal RD improves the surgical accuracy to identify the elbow rotation axis on fluoroscopy. CT scans of elbows from five volunteers were used to simulate fluoroscopy; the actual rotation axis was calculated with CT-based flexion–extension analysis. First, three observers measured the optimal RD on simulated fluoroscopy. The RD is defined as the distance between the dorsal part of the humerus and the projection of the posteromedial cortex of the distal humerus, divided by the anteroposterior diameter of the humerus. Second, eight trauma surgeons assessed the elbow rotation axis on simulated fluoroscopy. In a preteaching session, surgeons used traditional landmarks. The surgeons were then instructed how to use the optimal RD as additional landmark in a postteaching session. The deviation from the actual rotation axis was expressed as rotational and translational error (±SD). Measurement of the RD was robust and easily reproducible; the optimal RD was 45%. The surgeons identified the elbow rotation axis with a mean rotational error decreasing from 7.6° ± 3.4° to 6.7° ± 3.3° after teaching how to use the RD. The mean translational error decreased from 4.2 ± 2.0 to 3.7 ± 2.0 mm after teaching. The humeral RD as additional landmark yielded small but relevant improvements. Although fluoroscopy-based external fixator alignment to the elbow remains prone to error, it is recommended to use the RD as additional landmark.

Primary elbow arthroplasty: problems and solutions

Prosthetic replacement of the elbow joint has continued to improve over time. Widespread implantation of certain designs has led to identification a few successful elements of elbow arthroplasty, as well as several opportunities for improvement. Current hot topics in elbow arthroplasty include triceps-preserving exposures, implantation of components with better-expected wear performance, management of the ulnar nerve, prevention of infection, and the development of successful cementless components. Total elbow arthroplasty has the potential to improve pain, function and quality of life for many patients with articular destruction secondary to inflammatory arthropathy or as a consequence of trauma. Continued advances in this field are key to make this operation as reliable and lasting as hip or knee arthroplasty.

Distal Humeral Hemiarthroplasty Versus Total Elbow Arthroplasty for Acute Distal Humeral Fractures

For acute distal humeral fractures not amenable to open reduction and internal fixation, total elbow arthroplasty has become an established alternative. However, lifelong activity restrictions designed to prevent early mechanical failure make this a poor option for some patients. This has led to a renewed interest in distal humeral hemiarthroplasty. Using modern implants and techniques, distal humeral hemiarthroplasty has shown outcomes comparable to those of total elbow arthroplasty at short- to mid-term follow-up, with an overall higher but different complication rate. Long-term data are needed, but the available literature suggests that distal humeral hemiarthroplasty be considered as another option on the treatment spectrum in select patient populations. [Orthopedics. 2017; 40(1):13-23.].

Osseous Anatomy of the Distal Radioulnar Joint: An Assessment Using 3-Dimensional Modeling and Clinical Implications

PURPOSE

Using a novel technique, we assess and describe the distal radioulnar joint (DRUJ) anatomy. The purpose of this study was to provide the anatomic dimensions of the DRUJ and to evaluate contralateral symmetry.

METHODS

Computed tomography images of 100 cadaveric forearms were obtained. Three-dimensional models of the radius and ulna were generated and evaluated using 3-dimensional modeling software. Measurements of the radius of curvature of the sigmoid notch (SN) and ulnar head (UH), as well as the length of the SN and volar and dorsal lips were performed in the axial and coronal sequences. In addition, mid-coronal angular measurements were made of the SN and UH to quantify the obliquity of the DRUJ. All coronal measurements were performed with the forearm set to neutral rotation.

RESULTS

The average ulnar variance was -0.9 ± 1.8 mm. The radius of curvature of the UH (8.2 ± 1.3 mm) was markedly smaller than that of the SN (18.2 ± 8.5 mm). The length of the SN in coronal sequences increased from volar to dorsal by 65%. The mid-coronal angle (DRUJ obliquity) of the SN and UH measured 6.0 ± 9.9° and 18.0 ± 9.9°, respectively. A direct inverse correlation was demonstrated in the obliquity of the DRUJ and ulnar variance. All anatomic measurements were similar when comparing bilateral specimens.

CONCLUSIONS

The SN length tends to increase in size from volar to dorsal. Bilateral specimens from the same individual demonstrate similarities and can be cautiously used for comparison.

CLINICAL RELEVANCE

The relationships and measurements demonstrated in this study can be a guide when considering reconstructive procedures or dealing with complex fractures involving the DRUJ.

[Post-traumatic osteoarthritis of the elbow joint : Endoprosthetic options in young patients]

BACKGROUND

In young patients, post-traumatic osteoarthritis of the elbow is a rare condition. Whereas clinical manifestations often differ from radiological findings, pain and stiffness are variably combined in symptomatic forms. In deciding whether to perform surgery, the patient's age, activity level, and symptoms, as well as the location and severity of the osteoarthritis have to be taken into account. Elbow joint instability has to be identified to stop the post-traumatic osteoarthritic progress. If joint preserving surgical methods fail, diverse options for partial or total joint replacement are available.

THERAPY

The treatment goal in young patients, therefore, is to reduce pain with a sufficient range of elbow motion.

Elbow hemiarthroplasty for the management of distal humeral fractures: current technique, indications and results

There has been a growing recent interest in the use of elbow hemiarthroplasty for the treatment of distal humeral trauma in select patients. However, the current available evidence regarding outcome after elbow hemiarthroplasty is limited to case series and biomechanical data. Consequently, the procedure remains unfamiliar to many surgeons. The aim of the present review is to outline the evidence regarding elbow hemiarthroplasty and to use this, along with the author's experience, to better describe the indications, surgical technique and outcomes after this procedure.

Total Elbow Arthroplasty for Distal Humerus Fractures

Total elbow arthroplasty is a good treatment alternative for selected patients with distal humerus fractures. Its attractiveness is related to several factors, including the possibility of performing the procedure; leaving the extensor mechanism intact; faster, easier rehabilitation compared with internal fixation; and overall good outcomes reported in terms of both pain relief and function. Implant failure leading to revision surgery does happen, and patients must comply with certain limitations to extend the longevity of their implant. Development of high-performance implants may allow expanding the indications of elbow arthroplasty for fractures.

Surgical accuracy in identifying the elbow rotation axis on fluoroscopic images

PURPOSE

To assess the accuracy of surgeons in identifying elbow rotation axis (RA) on fluoroscopic images and to measure the interobserver variability.

METHODS

Five healthy subjects underwent 3-dimensional computed tomography (CT) analysis of their nondominant elbow. Real-time rotation software enabled surgeons to approximate the elbow RA on CT-reconstructed fluoroscopy, which was repeated twice with different starting positions to increase the number of observations. The surgeons used anatomical landmarks of choice. Analysis of variance (ANOVA) was used to determine structural error differences between surgeons, and intraclass correlation coefficients (ICCs) were used to determine the corresponding interobserver variability.

RESULTS

Eight subspecialty-trained trauma surgeons (P.K., N.W.L.S., V.M.d.J., P.J., G.M.K., R.W.P., T.S., B.A.v.D.) participated and attempted to identify the RA on reconstructed fluoroscopy. A total of 15 RA definitions on 5 elbows were recorded per surgeon. The surgeons had a mean rotational error of 5° (range, < 1°-13°) and mean translational error of 1 mm (range, < 1-8 mm), compared with the true elbow RA as measured by the 3-dimensional CT analysis. The ANOVA showed structural differences between surgeons in rotational and translational errors, indicating that some surgeons consistently had more accurately identified the elbow RA than others. The ICC was 0.12 for rotational error and 0.10 for translational error, indicating a large interobserver variability.

CONCLUSIONS

We show in this in vivo study that identification of the elbow RA on fluoroscopy is associated with substantial rotational errors and large inconsistencies among surgeons. Implementation of standardized anatomical landmarks is required to improve surgeons' accuracy. These landmarks should preferably take into account both the coronal and the sagittal planes, using the orientation of the capitellum and trochlea as well as the posterior distal humeral cortex.

TYPE OF STUDY/LEVEL OF EVIDENCE

Diagnostic II.

Post-traumatic osteoarthritis of the elbow

Post-traumatic osteoarthritis of the elbow is an uncommon condition in which the clinical manifestations are often at variance with the radiological findings. In symptomatic forms, pain and stiffness are variably combined. When non-operative management fails, the decision to perform surgery is taken on a case-by-case basis depending on age, activity level, patient discomfort, and osteoarthritis location and severity as assessed by CT scan arthrography. Elbow instability or subluxation should be sought. Post-traumatic elbow osteoarthritis raises difficult therapeutic problems in young patients. The goal of treatment is to obtain a low level of pain with sufficient motion range to ensure good function, while preserving future surgical options and delaying elbow arthroplasty to the extent possible.