Insights and trends review: the role of three-dimensional technology in upper extremity surgery.

The use of three-dimensional (3-D) technology in upper extremity surgery has the potential to revolutionize the way that hand and upper limb procedures are planned and performed. 3-D technology can assist in the diagnosis and treatment of conditions, allowing virtual preoperative planning and surgical templating. 3-D printing can allow the production of patient-specific jigs, instruments and implants, allowing surgeons to plan and perform complex procedures with greater precision and accuracy. Previously, cost has been a barrier to the use of 3-D technology, which is now falling rapidly. This review article will discuss the current status of 3-D technology and printing, including its applications, ethics and challenges in hand and upper limb surgery. We have provided case examples to outline how clinicians can incorporate 3-D technology in their clinical practice for congenital deformities, management of acute fracture and malunion and arthroplasty.

Porous metal wedge augments to address glenoid retroversion in anatomic shoulder arthroplasty: midterm update.

BACKGROUND: Wedge-shaped porous metal augments were used to address bone deficiency in shoulder arthroplasty as part of a hybrid combination of high-density polyethylene, polymethyl methacrylate bone cement, and porous metal implant. This article presents an ongoing review of the use of the generically designed augments in the shoulder to address glenoid retroversion as part of anatomic total shoulder arthroplasty (aTSA). MATERIALS: Seventy-five shoulders in 66 patients (23 women and 43 men, aged 42-85 years) with Walch grade B2 or C glenoids underwent porous metal glenoid augment (PMGA) insertion as part of aTSA. Patients underwent preoperative 3-dimensional (3D) templating; based on that planning, patients received either a 15° or 30° PMGA wedge (secured by screws to the native glenoid) to correct excessive glenoid retroversion before a standard glenoid component was implanted using bone cement. Neither patient-specific guides nor navigation were used. Intraoperative glenoid alignment was assessed using a reusable guide that referenced the anterior scapular neck. Patients were prospectively assessed using shoulder functional assessments (Oxford Shoulder Score [OSS], American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form [ASES], visual analog scale [VAS] pain scores, and forward elevation [FE]) preoperatively; at 3, 6, and 12 months postoperation; and yearly thereafter, with similar radiologic surveillance. RESULTS: Of the total consecutive series, 49 shoulders had a follow-up of greater than 24 months, with a median follow-up of 48 months (range: 24-87 months). For this cohort, median outcome scores improved for OSS (21 to 44), ASES (24 to 92), VAS (7 to 0), and FE (90° to 140°) from preoperative outcomes to the most recent review, respectively. Four patients died, but no others were lost to follow-up. Apart from 1 infection at 18 months postoperatively and 1 minor peg perforation, there were no complications, hardware failures, implant displacements, significant lucency, or posterior resubluxations. Radiographs showed good incorporation of the wedge augment, with correction of glenoid retroversion from median 22° (13° to 46°) to 4° (17° to anteversion 16°). All but 4 glenoids were corrected to within the target range (less than 10° retroversion), and only 2 glenoid components were implanted outside 15° of neutral glenoid version. CONCLUSIONS: The porous metal wedge-shaped augments effectively addressed posterior glenoid deficiency as part of aTSA for rotator cuff intact osteoarthritis, producing satisfactory clinical outcomes with no signs of impending future failure.

Computer Modelling of Wrist Biomechanics: Translation into Specific Tasks and Injuries.

BACKGROUND: The carpus is a complicated and functionally challenged mechanical system, advancements in the understanding of which have been compromised by the recognition that there is no standard carpal mechanical system and no typical wrist. This paper covers components of a larger project that seeks to develop a kinetic model of wrist mechanics to allow reverse analysis of the specific biomechanical controls or rules of a specific patient's carpus. Those rules, unique to each patient, could be used to create a forward synthesis mathematical model to reproduce the individual's anatomical motion in a virtual environment. OBJECTIVE AND METHODS: Based on the previous observations, the carpus essentially moves with only two degrees of freedom-pitch (flexion/extension) and yaw (radial deviation/ulnar deviation)-while largely preventing roll (pronation/supination). The objective of this paper is, therefore, to present the background and justification to support the rules-based motion (RBM) concept, which states that the motion of a mechanical system, such as the wrist, is the net interplay of four rules: morphology, constraint, interaction, and load. The stable central column theory (SCCT) of wrist mechanics applies the concept of RBM to the carpus, and by using a reverse engineering computational analysis model, a consistent pattern of isometric constraints was identified, creating a "two-gear four-bar" linkage. This study assessed the motion of the carpus using a 3D (three-dimensional) dynamic visualization model. The hypothesis was that the pattern and direction of motion of the proximal row and the distal row with respect to the immediately cephalad carpal bones or radius would be similar in all directions of wrist motion. To identify the unique motion segments, 3D models were created from five normal wrists that underwent CT scanning in multiple positions of radial and ulnar deviation as well as flexion and extension. Each carpal row (proximal and distal) was animated in a virtual environment with the cephalad carpal bones or radius held immobile. The rotational axis and position of each bone and each row were then compared in sagittal (flexion-extension) and coronal (radial and ulnar deviation) motion. RESULTS: The carpus appeared to have only two degrees of freedom, and yet was stable in those arcs with the loads applied proximally in the forearm. The proximal row moved in a singular arc, but with a varying extent during sagittal and coronal motion. The isometric constraints were consistent in both directions. The distal row moved on an axis formed by a pivot joint laterally (between the trapezium and scaphoid) and a saddle joint medially (between hamate and triquetrum). The sagittal and coronal alignment of this axis changed as the proximal row moved. This created a distinct pattern of row motion to achieve the various required positions of wrist function. On wrist radial deviation, the scaphoid (with the proximal row) was flexed and the distal row was extended, whereas, in wrist flexion, the scaphoid flexed (with the proximal row) and so did the distal row. The pattern was reversed in the opposite wrist movements. While the general direction of motion of each row was consistent, the extent was quite variable. CONCLUSION: This review supports the SCCT of carpal mechanics and the carpus acting as a twogear four-bar linkage, as well as the concept of RBM as a means to understand the biomechanics of the wrist, and how this is translated into specific functional tasks. More sophisticated 3D modelling will be required to further understand the specifics of carpal motion; however, reverse engineering of the specific rules that define each individual wrist can also be applied to a mathematical model to provide a "what if" test of particular surgical interventions for a variety of wrist injuries. The use of quantitative 3D Computed Tomography Scan (CT) analysis, surgical planning and virtual surgical intervention allows potential surgical solutions to be applied to a computer model of an injured wrist to test the possible outcomes and prognosis of a proposed treatment.

Arthroscopic rotator cuff repair using a transosseous knotless anchor (ATOK).

BACKGROUND: This article reviews the clinical and radiographic outcomes in a noninferiority trial use of a transosseous knotless anchor to perform arthroscopic rotator cuff repairs in a patient cohort that have an increased incidence of osteoporosis. METHODS: Patients aged over 60 with a documented rotator cuff tear and who failed a rehab program underwent repair using an arthroscopic transosseous knotless (ATOK) anchor. Patients were prospectively reviewed using shoulder functional assessments (age-adjusted Constant score, Oxford Shoulder Score, American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form [ASES], visual analog scale [VAS] pain scores), and underwent preoperative as well as 1-, 3-, and 12-month postoperative magnetic resonance imaging. RESULTS: 15 patients had undergone rotator cuff repair using the ATOK and were followed for a minimum of 24 months (range 24-30 months). From preoperative to 24 months post repair, median scores improved for ASES (61-89), Oxford (26-44), Constant (62-91), and VAS Pain (5-0.5). Four patients developed a partial retear of their repair, but only 1 patient sustained a complete retear: Sugaya type I, 10; type II, 1; type III, 2; type IV, 1; and type V, 1. No anchors were displaced, and there were no osteolysis, neurologic, or technique-related complications. CONCLUSIONS: Arthroscopic rotator cuff repairs using a transosseous knotless technique has achieved a satisfactory outcome in this group of patients, who typically have poor bone quality, increasing the risk of antegrade anchor pullout. This approach would appear to combine the potential biomechanical and biological advantages of a transosseous repair technique, with the benefits of the lower morbidity arthroscopic surgical approach.

3D Dynamic Analysis of the Wrist.

With advances in imaging and computing technology the greater capacity to diagnose, plan and deliver care to patients with hand and wrist disorder is being realised. Work in our laboratory, has been able to identify certain specific rules that control wrist motion, and is a step on the pathway to creating a unified theory of carpal mechanics which will incorporate a kinetic biomechanical model. This will allow more precise anatomically based as well as quantitative diagnoses, but also an ability to test a proposed intervention in a "what if" scenario.

A comprehensive classification of proximal humeral fractures: HGLS system.

BACKGROUND: This study assessed the intraobserver and interobserver reliability of a binary classification system using an easy-to-remember acronym (the HGLS system--based on the reappraisal of Codman's description by Hertel et al) and compared it with the AO and Neer systems. MATERIALS AND METHODS: Forty-seven proximal humeral fractures in 47 patients treated at the Department of Orthopaedics and Trauma, Royal Adelaide Hospital, Adelaide, Australia, were identified in the period from July 2007 until January 2008. Fractures of the proximal humerus were examined with anteroposterior, lateral, and axillary radiographs. Three independent reviewers classified the fractures using the AO, Neer, and HGLS systems. Reclassification of the same fractures was undertaken after a 6-month interval, and interobserver and intraobserver correlation, by use of the κ statistic, was calculated for all 3 classification systems. RESULTS: The mean age of patients was 64.5 years (range, 16-95 years). The interobserver correlations for the AO system (κ value, 0.47) and Neer system (κ value, 0.44) were graded as poor and were consistent with the values of previously published studies. The HGLS classification showed good interobserver agreement for all 3 examiners at the first interpretation (κ value, 0.73) and second interpretation (κ value, 0.61). Good intraobserver agreement after a 6-month period was also seen for the HGLS classification (κ values, 0.87-0.92) compared with the AO system (κ, 0.61-0.71) and Neer system (κ, 0.42-0.77). CONCLUSION: The HGLS system provided a more reliable description of fractures of the proximal humerus compared with the Neer and AO systems. Further studies are necessary to assess the validity of the HGLS system.

Hemiarthroplasty vs total shoulder replacement for rotator cuff intact osteoarthritis: how do they fare after a decade?

BACKGROUND: We compared hemiarthroplasty (HA) and total shoulder replacement (TSR) for the treatment of osteoarthritis at minimum of 10 years from primary arthroplasty. METHODS: Thirty-three patients (13 HA and 20 TSR) were intraoperatively randomized to HA or TSR after glenoid exposure and were assessed to a minimum of 10 years postoperatively. Apart from those who died, no patients were lost to follow-up. RESULTS: At 6 months and 1 year, the TSR patients had less pain than the HA patients (P < .05), and this became more apparent at 2 years postoperatively (P < .02). There were no statistically significant differences between the groups at 10 years with respect to pain, function, and daily activities. No patients in the HA group rated their shoulders as pain-free at 10 years; however, 42% of the surviving TSR patients rated their shoulders as pain-free at 10 years. Four HA patients were revised to TSR due to severe pain secondary to glenoid erosion. Two shoulders in the TSR group have been revised. Nine of the 13 HA patients (69%) and 18 of the 20 TSR patients (90%) remained in situ at death or at the 10-year review. CONCLUSION: TSR has advantages over HA with respect to pain and function at 2 years, and there has not been a reversal of the outcomes on longer follow-up. This longer-term review does not support the contention that HA will avoid later TSR complications, and in particular, an unacceptable rate of glenoid component failure.

Relative contributions of the infraspinatus and deltoid during external rotation in patients with symptomatic subacromial impingement.

A principal cause of subacromial impingement (SAI) is failure of the rotator cuff to center the humeral head in the glenoid during shoulder motion, counteracting the effect of the deltoid. As rehabilitation of the rotator cuff endeavors to restore balance between these muscle groups, the purpose of this companion study was to evaluate, in the symptomatic shoulders of patients with SAI, (1) the conditions of resisted isometric external rotation (ER) that optimized the contribution of the infraspinatus and (2) the load of ER at which adduction was most effective at reducing the deltoid contribution and then to compare this with the relative contribution of the infraspinatus and the posterior and middle deltoid in asymptomatic shoulders. In 14 subjects (18 shoulders) with SAI, surface electromyographic activity of the infraspinatus and the posterior and middle deltoid and pectoralis major was recorded at low, medium, and high loads of resisted isometric ER, with and without adduction. These data were normalized to find each muscle's relative contribution to the task and were compared with normalized data from subjects with healthy shoulders. In subjects with SAI, low loads of isometric ER (10%-40% maximum voluntary isometric contraction) optimized the relative contribution of the infraspinatus. Adduction with isometric ER at 10% maximum voluntary isometric contraction reduced the middle deltoid involvement. Higher loads preferentially activated the middle deltoid over the infraspinatus and may have effected unwanted humeral head superior translation, counteracting the presumed benefits of rotator cuff ER exercises. An individualized loading regimen and the use of surface electromyography may have significant implications during rotator cuff rehabilitation.

Relative contributions of infraspinatus and deltoid during external rotation in healthy shoulders.

Balanced forces around the shoulder are important for normal function; however, rehabilitation guidelines are not well defined because the muscle contributions and optimal exercise technique to recruit them are poorly understood. This study aimed to determine (1) the conditions of resisted isometric external rotation that optimized the contribution of infraspinatus and (2) the load of external rotation at which the adduction strategy was most effective at reducing deltoid contributions. Eighteen subjects with healthy shoulders (n = 36) performed resisted isometric external rotation at 3 increasing loads--10%, 40%, and 70% of their maximal resisted external rotation voluntary isometric contraction--with and without adduction. Surface electromyographic activity of the infraspinatus, posterior and middle deltoid, and pectoralis major was recorded and normalized against the average activity of all 4 muscles, representing each muscle's relative contribution to the task. To optimize the relative contribution of the infraspinatus with the least deltoid involvement during isometric external rotation, a load between 10% and 40% maximal voluntary isometric contraction is appropriate. At low loads, use of the adduction strategy during external rotation reduces middle deltoid involvement. In contrast, the posterior deltoid is activated in parallel with the infraspinatus at low loads and may even act as an adductor with the arm by the side. This study provides a useful guide to optimize rehabilitative exercises for rotator cuff dysfunction; in particular, highlighting that activation of the deltoid could be counterproductive to infraspinatus retraining.