Roger Emery

A review of the Constant score: Modifications and guidelines for its use

The requirement to assess surgical results and the means of quantifying them have always provoked intense debate. Since Codman’s introduction of ‘‘the end result idea,’’ the main aim in assessment has not changed, but our requirements are now more sophisticated and include observation of natural history, follow-up, and disability quantification. The Constant score was devised by Christopher Constant with the assistance of the late Alan Murley during the years 1981-1986. The score was first presented in a university thesis in 1986 and the methodology published in 1987. This functional assessment score was conceived as a system of assessing the overall value, or functional state, of a normal, a diseased, or a treated shoulder. If universally accepted, it would further progress in clinical research in shoulder surgery and enhance the value of multicenter trials. In this score, 35 points are allocated for subjective assessments of pain and activities of daily living and 65 points are available for objective measures of range of movement and shoulder strength. A young healthy patient can therefore have a maximum score of 100 points.

Dead Men and Radiologists Don't Lie: A Review of Cadaveric and Radiological Studies of Rotator Cuff Tear Prevalence

INTRODUCTION Rotator cuff tears are a common pathology, with a varied prevalence reported. PATIENTS AND METHODS A literature review was undertaken to determine the cadaveric and radiological (ultrasonography and magnetic resonance imaging [MRI]) prevalence of rotator cuff tear. The radiological studies were subdivided into symptomatic and asymptomatic subjects. RESULTS Cadaveric rotator cuff tears were found in 4629 shoulders of which only 2553 met the inclusion criteria. The prevalence of full-thickness tears was 11.75% and partial thickness 18.49% (total tears 30.24%). The total tear rate in ultrasound asymptomatic was 38.9% and ultrasound symptomatic 41.4%. The total rate in MRI asymptomatic was 26.2% whilst MRI symptomatic was 49.4%. DISCUSSION The unselected cadaveric population should contain both symptomatic and asymptomatic subjects. A prevalence of tears between the symptomatic and asymptomatic radiological groups would be expected. However, apart from the MRI asymptomatic group, the radiological prevalence of rotator cuff tears exceeds the cadaveric. CONCLUSIONS Rotator cuff tears are frequently asymptomatic. Tears demonstrated during radiological investigation of the shoulder may be asymptomatic. It is important to correlate radiological and clinical findings in the shoulder.

A BIOMECHANICAL EVALUATION OF SUTURE ANCHORS IN REPAIR OF THE ROTATOR CUFF

Repair of the rotator cuff requires secure reattachment, but large chronic defects cause osteoporosis of the greater tuberosity which may then have insufficient strength to allow proper fixation of the tendon. Recently, suture anchors have been introduced, but have not been fully evaluated. We have investigated the strength of suture-to-anchor attachment, and the use of suture anchors in repairs of the rotator cuff either to the greater tuberosity or the lateral cortex of the humerus. The second method gave a significant increase in the strength of the repair (p = 0.014). The repairs were loaded cyclically and failed at low loads by cutting into bone and tendon, casting doubt on the integrity of the repair in early mobilisation after surgery. Repairs with suture anchors did not perform better than those with conventional transosseous attachment.

Evaluation of VEGF-mediated signaling in primary human cells reveals a paracrine action for VEGF in osteoblast-mediated crosstalk to endothelial cells†

Communication between endothelial and bone cells is crucial for controlling vascular supply during bone growth, remodeling, and repair but the molecular mechanisms coordinating this intercellular crosstalk remain ill‐defined. We have used primary human and rat long bone‐derived osteoblast‐like cells (HOB and LOB) and human umbilical vein endothelial cells (HUVEC) to interrogate the potential autocrine/paracrine role of vascular endothelial cell growth factor (VEGF) in osteoblast:endothelial cell (OB:EC) communication and examined whether prostaglandins (PG), known modulators of both OB and EC behavior, modify VEGF production. We found that the stable metabolite of PGI2, 6‐keto‐PGF1α and PGE2, induced a concentration‐dependent increase in VEGF release by HOBs but not ECs. In ECs, VEGF promoted early ERK1/2 activation, late cyclooxygenase‐2 (COX‐2) protein induction, and release of 6‐keto‐PGF1α. In marked contrast, no significant modulation of these events was observed in HOBs exposed to VEGF, but LOBs clearly exhibited COX‐dependent prostanoid release (10‐fold less than EC) following VEGF treatment. A low level of osteoblast‐like cell responsiveness to exogenous VEGF was supported by VEGFR2/Flk‐1 immunolabelling and by blockade of VEGF‐mediated prostanoid generation by a VEGFR tyrosine kinase inhibitor (TKI). HOB alkaline phosphatase (ALP) activity was increased following long‐term non‐contact co‐culture with ECs and exposure of ECs to VEGF in this system further increased OB‐like cell differentiation and markedly enhanced prostanoid release. Our studies confirm a paracrine EC‐mediated effect of VEGF on OB‐like cell behavior and are the first supporting a model in which prostanoids may facilitate this unidirectional VEGF‐driven OB:EC communication. These findings may offer novel regimes for modulating pathological bone remodeling anomalies through the control of the closely coupled vascular supply. J. Cell. Physiol. 214: 537–544, 2008.

A standard method of shoulder strength measurement for the Constant score with a spring balance

The strength component of the Constant score has been criticized for its lack of a precisely defined measurement method. A series of experiments was performed to compare three different methods in normal and pathologic shoulders with the use of a standard test position. These were (1) the Isobex isometric dynamometer, (2) Constants unsecured spring balance, and (3) a new modification in which the spring balance is fixed at one end and the reading is taken after 5 seconds of maximum effort. The results suggest that this simple modification with a low-cost spring balance can give similar values to those from the Isobex. The need for precision of terms and a definition of the method is discussed, and recommendations for the standardization of the many variables in making this measurement are made.

Mechanical factors in the initiation and propagation of tears of the rotator cuff: QUANTIFICATION OF STRAINS OF THE SUPRASPINATUS TENDON IN VITRO

Differential strain has been proposed to be a causative factor in failure of the supraspinatus tendon. We quantified the strains on the joint and bursal sides of the supraspinatus tendon with increasing load (20 to 200 N) and during 120 degrees of glenohumeral abduction with a constant tensile load (20 to 100 N). We tested ten fresh frozen cadaver shoulders on a purpose-built rig. Differential variable reluctance extensometers allowed calculation of the strain. Static loading to 100 N or more increased strains on the joint side significantly more than on the bursal side. During glenohumeral abduction an increasing and significant difference in strain was measured between the joint and bursal sides of the supraspinatus tendon, which reached a maximum of 10.6% at abduction of 120 degrees. The joint side strain of 7.5% reached values which were previously reported to cause failure. Differential strain causes shearing between the layers of the supraspinatus tendon, which may contribute to the propagation of intratendinous defects that are initiated by high joint side strains.

Validation of orthopaedic bench models for trauma surgery

The aim of this study was to validate the use of three models of fracture fixation in the assessment of technical skills. We recruited 21 subjects (six experts, seven intermediates, and eight novices) to perform three procedures: application of a dynamic compression plate on a cadaver porcine model, insertion of an unreamed tibial intramedullary nail, and application of a forearm external fixator, both on synthetic bone models. The primary outcome measures were the Objective Structural Assessment of technical skills global rating scale on video recordings of the procedures which were scored by two independent expert observers, and the hand movements of the surgeons which were analysed using the Imperial College Surgical Assessment Device. The video scores were significantly different for the three groups in all three procedures (p < 0.05), with excellent inter-rater reliability (alpha = 0.88). The novice and intermediate groups specifically were significantly different in their performance with dynamic compression plate and intramedullary nails (p < 0.05). Movement analysis distinguished between the three groups in the dynamic compression plate model, but a ceiling effect was demonstrated in the intramedullary nail and external fixator procedures, where intermediates and experts performed to comparable standards (p > 0.6). A total of 85% (18 of 21) of the subjects found the dynamic compression model and 57% (12 of 21) found all the models acceptable tools of assessment. This study has validated a low-cost, high-fidelity porcine dynamic compression plate model using video rating scores for skills assessment and movement analysis. It has also demonstrated that Synbone models for the application of and intramedullary nail and an external fixator are less sensitive and should be improved for further assessment of surgical skills in trauma. The availability of valid objective tools of assessment of surgical skills allows further studies into improving methods of training.

Fixation of the reversed shoulder prosthesis

The last decade has seen an increased interest in reversed shoulder prostheses. Success rates with these designs have been varied, with initial performance marred by failures resulting from improper implant alignment and an emerging engineering understanding. Competitor products to the well-documented Grammont design have yielded increasingly high success rates. Understanding the relationships between implant design, surgical procedure, and clinical outcome is important so that current results can be improved upon. This study considers the performance of 3 different reversed shoulder designs from the perspective of osseointegration, with the results broadly validated through comparison with experimental data. Finite element modeling was used to clarify the relationships between lateral offset of the center of rotation, screw insertion angle, screw length, screw diameter, bone material quality, and the potential for interdigitation of the supporting bone onto the reversed prosthesis. The results indicate that screw length, insertion angle, and diameter, when maximized, allow the least relative motion between the implant and underlying bone. When the bone is stiffer, the relative motion of the implant is lower. In almost all scenarios modeled, the interface micromotion was small enough to suggest that the glenoid was stable enough to encourage bone ingrowth across the majority of the bone-implant interfaces.

Pioneers of shoulder replacement: Themistocles Gluck and Jules Emile Péan

Dr. Jules Emile Péan is widely credited with having performed the first total shoulder replacement March 11, 1893, at the Hôpital International in Paris. However, in his original report Péan refers to the work of Themistocles Gluck as being the inspiration for his shoulder prosthesis, a fact understated if not completely overlooked during the last hundred years. This article therefore attempts to reappraise the relative contributions of these two pioneering surgeons to shoulder arthroplasty.

Acromial spur formation in patients with rotator cuff tears.

In this study we analyzed the acromial spurs of 15 patients with impingement syndrome undergoing open rotator cuff repair. Mineral apposition analysis and quantitative cytochemical techniques for glucose-6-phosphate dehydrogenase (G6PD) activity (pentose phosphate pathway), alkaline phosphatase (ALP) activity (osteoblast activity), and tartrate-resistant acid phosphatase (TRAP) activity (osteoclast phenotype) were used to examine the distribution and level of activity of selected marker enzymes within the acromial spur insertion into the coracoacromial ligament in order to establish whether local behavior of bone cells is consistent with the proposed secondary development of the acromial spur. Our results indicate that G6PD and ALP activity was higher in osteoblasts on the inferior surface compared with the superior surface of the acromial spur in all patients (P <.001). This area correlated to the most intense area of mineral apposition shown by dual tetracycline labeling. TRAP activity revealed a heterogeneous distribution within the samples. A greater G6PD activity per cell (mean increase of 87%) was seen at the tip compared with that in post- and pre-tip zones within the coronal plane (P <.0002). The qualitative and quantitative enzyme analyses show that the acromial insertion of the coracoacromial ligament is actively involved in bone turnover. The spatial distribution patterns of metabolically active bone-forming osteoblastic cells compared with a heterogeneous distribution of TRAP-positive osteoclasts provide evidence of bone remodeling consistent with the morphologic contours of the acromial enthesis. The sites of oxytetracycline labeling appear to correlate with the sites of high ALP and G6PD activity, which supports the concept of spur formation being a secondary phenomenon in the presence of established rotator cuff tears.