Implication of bone morphology in degenerative rotator cuff lesions: A prospective comparative study between greater tuberosity angle and critical shoulder angle.

BACKGROUND: Degenerative rotator cuff tear is a frequent and multifactorial pathology. The role of bone morphology of the greater tuberosity and lateral acromion has been validated, and can be measured with two plain radiographic markers on true anteroposterior views: the greater tuberosity angle (GTA) and the critical shoulder angle (CSA). However, the interdependence of both markers remains unknown, as well as their relationship with the level of professional and sports activities involving the shoulder. The aim of this prospective comparative study was to describe the correlation between the GTA and CSA in patients with degenerative rotator cuff tears. HYPOTHESIS: GTA and CSA are independent factors from one another and from demographic factors, such as age, dominance, sports, or professional activities. PATIENT AND METHODS: All patients presenting to a shoulder specialized clinic were assigned to two groups. The first consisted of patients with a symptomatic degenerative rotator cuff tear visible on MRI and the control group consisted of patients with any other shoulder complaints and no history or visible imaging of any rotator cuff lesion. RESULTS: There were 51 shoulders in 49 patients in the rotator cuff tear group (RCT) and 53 shoulders in 50 patients in the control group. Patient demographics were similar in both groups. Mean GTA was 72.1°±3.7 (71.0-73.1) in the RCT group and 64.0°±3.3 (63.1-64.9) in the control group (p<0.001). Mean CSA was 36.7°±3.7 (35.7-37.8) in the RCT group, and 32.1°±3.7 (31.1-33.1) in the control group (p<0.001). A summation of GTA and CSA values over 103° increased the odds of having a rotator cuff tear by 97-fold (p<0.001). There was no correlation between GTA and CSA, nor between GTA or CSA and age, sex, tear size, or dominance. Patients with different levels of professional and sports activities did not have significantly different GTA or CSA values. CONCLUSION: GTA and CSA are independent radiologic markers that can reliably predict the presence of a degenerative rotator cuff tear. A sum of both values over 103° increases the odds of having a rotator cuff tear by 97-fold. These markers are not correlated with patient demographic or environmental factors, suggesting that the variability of the native acromion and greater tuberosity morphology may be individual risk factors for rotator cuff tear. LEVEL OF EVIDENCE: II; diagnostic study.

A single dose of tranexamic acid reduces blood loss after reverse and anatomic shoulder arthroplasty: a randomized controlled trial.

BACKGROUND: Hematoma formation and the need for blood transfusions are commonly reported complications after shoulder arthroplasty. Tranexamic acid (TXA) has been widely used in hip and knee arthroplasty to decrease perioperative blood loss. The role of TXA is still being established in shoulder arthroplasty. MATERIALS AND METHODS: We conducted a double-blind randomized controlled trial comparing intravenous TXA vs. placebo in 60 patients undergoing primary anatomic or reverse shoulder arthroplasty. Of these patients, 29 received a placebo whereas 31 received a single dose of 2 g of intravenous TXA. Patient demographic characteristics, as well as drain tube output, blood loss, hematoma formation, transfusion requirement, length of hospital stay, and pain score, were recorded. Patients were followed up for 12 weeks to assess for complications. RESULTS: Patients who received TXA had a lower drain tube output at all time points: 41 mL vs. 133 mL at 6 hours, 75 mL vs. 179 mL at 12 hours, and 94 mL vs. 226 mL at 24 hours (P < .001 for all). They also had a higher postoperative hemoglobin (Hb) level (12.3 g/dL vs. 11.4 g/dL, P = .009), lower change in Hb level (1.7 g/dL vs. 2.3 g/dL, P = .011), lower total Hb loss (0.078 g vs. 0.103 g, P = .042), lower blood volume loss (0.55 L vs. 0.74 L, P = .021), higher postoperative hematocrit level (36.7% vs. 34.6%, P = .020), and lower hematocrit change (5.4% vs. 7.6%, P = .022). There was no significant difference in pain score or length of hospital stay, and no patients required a transfusion. CONCLUSION: A single dose of 2 g of intravenous TXA decreases blood loss and drain tube output in primary anatomic and reverse arthroplasty of the shoulder. No differences were detected in the occurrence of complications, need for transfusion, pain score, or length of hospital stay. With the mounting evidence now available, patients undergoing elective primary shoulder arthroplasty should be given intravenous TXA to decrease perioperative blood loss.

Accuracy of arthroscopic fluid pump systems in shoulder surgery: a comparison of 3 different pump systems.

BACKGROUND: Extra-articular fluid extravasation is a known complication during shoulder arthroscopy. The risk and amount of extravasation to a large degree is dependent on the fluid pressure delivered to the surgical site. Accurate measurement, knowledge, and control of the pressure delivered is thus important to surgeons, anesthetists, and the patient. The purpose of this study was to compare the pressure measurement accuracy of 3 arthroscopic fluid pumps, with 2 of them having 2 different settings. METHODS: Twenty-five patients (n = 5 per group) undergoing shoulder arthroscopy were selected. Three different arthroscopic fluid pumps (ConMed 24K, Stryker Crossflow, Arthrex Dual Wave) were tested in 5 different operational settings (Stryker, standard and dynamic mode; ConMed, with and without TIPS; Arthrex Dual Wave). In each operation, the set pump pressures and the subsequently delivered intra-articular surgical site fluid pressures were measured by a spinal needle connected to an anesthetic standard pressure transducer attached to the anesthetic machine. Independent measures of the surgical site pressures were obtained before multiple portals were created or extravasation had occurred. Measurements were taken at the beginning of surgery. RESULTS: Measurements of the mean intra-articular pressure were found to not be significantly different from the set pressure for the ConMed 24K with TIPS (0.98 ± 0.02-fold) and Stryker Crossflow in standard mode (0.98 ± 0.02-fold). However, actual pressure was significantly greater than the set pressure for the ConMed 24K without TIPS (by 1.30 ± 0.13-fold), Stryker Crossflow in dynamic mode (by 1.82 ± 0.08-fold), and Arthrex Dual Wave (by 2.19 ± 0.06-fold). CONCLUSION: Independently measured intra-articular pressure can be more than double the set pressure for some arthroscopic pumps. Measuring intra-articular pressure can thus aid in adjusting the set pressure. This could minimize the risk of intraoperative complications.

A Biomechanical Comparison of Different Suture Materials Used for Arthroscopic Shoulder Procedures.

PURPOSE: To evaluate the viscoelastic properties of 4 commercially available cord-like sutures and 2 commercially available suture tapes when subjected to physiological loads, as well as to compare them with each other and to identify the clinically most desirable combination of suture material properties. METHODS: Six suture materials (Ethibond, FiberWire, FiberTape, Orthocord, Ultrabraid, and Ultratape) underwent creep testing (n = 7, 60 N, 10 minutes) to determine specimen stiffness, initial elongation at 60 N of load, static creep (during 10 minutes of loading), and relaxed elongation (material recovery 3 minutes after removal of load). Furthermore, cyclic testing (n = 7, 10-45 N, 0.5 Hz, 500 cycles) was carried out to determine dynamic creep, peak-to-peak displacement, and relaxed elongation. Mechanical testing was conducted on a material testing machine in 37°C phosphate-buffered saline solution. RESULTS: FiberTape showed the greatest stiffness (23.9 ± 3.2 N/mm, P < .001), the smallest amounts of static (0.38 ± 0.10 mm, P < .001) and dynamic (0.16 ± 0.09 mm, P = .003) creep, and the smallest peak-to-peak displacement (0.20 ± 0.02 mm, P < .001). FiberTape and FiberWire showed the smallest initial elongation (1.17 ± 0.17 mm and 1.63 ± 0.25 mm, respectively; P < .001). Ultrabraid showed the greatest relaxed elongation, both statically (4.73 ± 0.73 mm, P < .001) and dynamically (4.18 ± 0.83 mm, P = .002). CONCLUSIONS: FiberTape consistently displayed less creep, greater stiffness, and less extensibility than the other suture types. Ultrabraid showed the largest amount of relaxed elongation on both static and dynamic testing. CLINICAL RELEVANCE: When considering high stiffness in combination with low initial extension and low static creep to be ideal parameters to achieve optimal initial construct stability and considering low dynamic creep in combination with low peak-to-peak displacement to be ideal conditions for the repetitive loading of the construct during the healing process, tapes seem to be superior to cord-like sutures for performing rotator cuff repair.

Comparative analysis of 2 glenoid version measurement methods in variable axial slices on 3-dimensionally reconstructed computed tomography scans.

BACKGROUND: Most glenoid version measurement methods have been validated on 3-dimensionally corrected axial computed tomography (CT) slices at the mid glenoid. Variability of the vault according to slice height and angulation has not yet been studied and is crucial for proper surgical implant positioning. The aim of this study was to analyze the variation of the glenoid vault compared with the Friedman angle according to different CT slice heights and angulations. The hypothesis was that the Friedman angle would show less variability. MATERIALS AND METHODS: Sixty shoulder CT scans were retrieved from a hospital imaging database and were reconstructed in the plane of the scapula. Seven axial slices of different heights and coronal angulations were selected, and measurements were carried out by 3 observers. RESULTS: Mid-glenoid mean version was -8.0° (±4.9°; range, -19.6° to +7.0°) and -2.1° (±4.7°; range, -13.0° to +10.3°) using the vault method and Friedman angle, respectively. For both methods, decreasing slice height or angulation did not significantly alter version. Increasing slice height or angulation significantly increased anteversion for the vault method (P < .001). Both interobserver reliability and intraobserver reliability were significantly higher using the Friedman angle. CONCLUSION: Version at the mid and lower glenoid is similar using either method. The vault method shows less reliability and more variability according to slice height or angulation. Yet, as it significantly differs from the Friedman angle, it should still be used in situations where maximum bone purchase is sought with glenoid implants. For any other situation, the Friedman angle remains the method of choice.

The greater tuberosity angle: a new predictor for rotator cuff tear.

BACKGROUND: The implication of scapular morphology in rotator cuff tears has been extensively studied. However, the role of the greater tuberosity (GT) should be of equal importance. The aim of this study was to propose a new radiographic marker, the GT angle (GTA), which measures the position of the GT in relation to the center of rotation of the humeral head. The hypothesis was that a higher angle value would be associated with a higher likelihood in detecting a rotator cuff tear. METHODS: During 1 year, patients were prospectively recruited from a single institution specialized shoulder clinic in 2 different groups. The patient group consisted of individuals with a degenerative rotator cuff tear involving at least the supraspinatus. The control group consisted of individuals with no rotator cuff pathology. Individuals in both groups with congenital, post-traumatic, or degenerative alterations of the proximal humerus were excluded. The GTA was measured on an anteroposterior shoulder x-ray image with the arm in neutral rotation by 3 observers at 2 different times. RESULTS: The study recruited 71 patients (33 patients, 38 controls). Mean GTA value was 72.5° (range, 67.6°-79.2°) in patients and 65.2° (range, 55.8°-70.5°) for controls (P <.001). A value above 70° resulted in 93-fold higher odds of detecting a rotator cuff tear (P <.001). Interobserver and intraobserver reliability were high. CONCLUSIONS: GT morphology is implicated in rotator cuff tears. The GTA is a reliable radiographic marker, with more than 70° being highly predictive in detecting such lesions.

Contamination of the Surgical Field with Propionibacterium acnes in Primary Shoulder Arthroplasty.

BACKGROUND: Propionibacterium acnes is a common pathogen identified in postoperative shoulder infection. It has been shown to be present in culture specimens during primary shoulder arthroplasty; however, recent work has suggested that it is most likely to be a contaminant. Our aim was to identify the potential sources of contamination in shoulder arthroplasty. METHODS: Tissue swabs were obtained for microbiological analysis from consecutive patients undergoing primary shoulder arthroplasty. Routine surgical technique was maintained, and 5 specimens were taken from different sites: (1) the subdermal layer, (2) the tip of the surgeon's glove, (3) the inside scalpel blade (used for deeper incision), (4) the forceps, and (5) the outside scalpel blade (used for the skin incision). RESULTS: Forty patients (25 female patients and 15 male patients) were included. Thirteen (33%) of the 40 patients had at least 1 culture specimen positive for P. acnes. Two (8%) of the 25 female patients and 11 (73%) of the 15 male patients had ≥1 culture specimen positive for P. acnes. The most common site of growth of P. acnes was the subdermal layer (12 positive samples), followed by the forceps (7 positive samples), the tip of the surgeon's glove (7 positive samples), the outside scalpel blade (4 positive samples), and the inside scalpel blade (1 positive sample). There were 27 of 75 swabs that were positive on culture for P. acnes in male patients compared with 4 of 125 swabs in female patients. Male patients had 66 times (95% confidence interval, 6 to 680 times) higher odds of having a positive culture indicating subdermal colonization compared with female patients (p < 0.001). CONCLUSIONS: P. acnes is a common contaminant of the surgical field in primary shoulder arthroplasty. The subdermal layer may be the source of this contamination, and the prevalence of P. acnes in the surgical wound may be due to the surgeon's manipulation with gloves and instruments. Our findings are consistent with those regarding the increased rates of P. acnes bacterial load and intraoperative growth in male patients compared with female patients. CLINICAL RELEVANCE: P. acnes is likely to be spread throughout the surgical field from the subdermal layer via soft-tissue handling by the surgeon and instruments. Strategies need to be utilized to minimize this contact and to reduce the chance of colonization.

Low rate of Propionibacterium acnes in arthritic shoulders undergoing primary total shoulder replacement surgery using a strict specimen collection technique.

BACKGROUND: Propionibacterium acnes is a recognized pathogen in postoperative shoulder infections. A recent study reported growth of P acnes in 42% of glenohumeral joints in primary shoulder arthroplasty, concluding that P acnes may cause shoulder osteoarthritis. Whether these results reflect true bacterial infection or specimen contamination is unclear. Our prospective study aimed to determine the rate of P acnes infection in arthritic shoulders using a strict specimen collection technique. METHODS: We used modified Oxford protocol to collect tissue specimens from the glenohumeral joint of 32 consecutive patients undergoing primary shoulder arthroplasty. Specimens were cultured specifically for P acnes. Diagnosis of P acnes infection required 2 or more positive cultures and histopathology compatible with infection. RESULTS: Three of 32 patients had a positive culture for P acnes. Overall, 3.125% of specimens grew P acnes without histologic evidence of infection. There were no patients with P acnes infection. The difference in culture rates between patients with idiopathic osteoarthritis and those with a predisposing cause for osteoarthritis was not significant. CONCLUSIONS: We found a low rate of positive cultures for P acnes, but no P acnes infection and no difference between types of osteoarthritis. These results do not support a cause-and-effect relationship between P acnes and osteoarthritis. The differing results from previous studies are likely explained by our strict specimen collection technique, reflecting different rates of contamination rather than infection. That P acnes contamination occurs in primary shoulder arthroplasty is concerning. Further studies are needed to assess the rates of contamination in shoulder surgery, its clinical effect, and to determine optimal antibiotic prophylaxis.

The Latarjet-Patte procedure for recurrent anterior shoulder instability in contact athletes.

Recurrent anterior shoulder instability is common in contact athletes and the high-energy injuries seen in this group make them more prone to bone loss. Athletes with recurrent instability and associated bone loss have high failure rates when treated with a soft tissue reconstruction procedure. Therefore it is preferred to manage recurrent instability in contact athletes with the Latarjet-Patte procedure. In this article, the authors describe their technique. They have found this procedure to be safe and effective, with very low recurrence and early return to sport. A meticulous surgical technique is important to avoid intraoperative and postoperative complications.

The Latarjet-Patte procedure for recurrent anterior shoulder instability in contact athletes.

The Latarjet-Patte procedure satisfies all of the requirements for treating recurrent anterior instability in contact athletes and is therefore their preferred management in this patient group.

Coracoid graft dimensions after harvesting for the open Latarjet procedure.

BACKGROUND: Recent studies have reported the theoretic amount of coracoid graft available for harvesting with the Latarjet procedure. Our aim was to investigate the actual dimensions of coracoid grafts harvested using a standardized technique. We also hoped to confirm previous recommendations regarding placement of the inferior glenoid drill hole to avoid lateral overhang of the graft. MATERIALS AND METHODS: Intraoperative measurements were taken after coracoid graft harvesting and preparation during the Latarjet procedure. Specifically, we measured the length of coracoid, thickness of coracoid, distance from the inferior drill hole to the lateral margin of the graft, distance between drill holes, width at the level of the superior drill hole, and width at the level of the inferior drill hole. RESULTS: Data were collected from 76 Latarjet procedures (67 men, 9 women). Patients were an average age of 28.7 years (range 16-67 years). Mean measurements were length of coracoid graft, 26.4 ± 2.9 mm; thickness, 9.3 ± 1.4 mm; distance from the edge of the inferior drill hole to the lateral margin of the graft, 5.7 ± 1.1 mm; distance between drill holes, 7.8 ± 1.9 mm; width at the level of the superior drill hole, 14.1 ± 1.8 mm; and width at the level of the inferior drill hole, 13.3 ± 1.8 mm. CONCLUSIONS: Using a standardized surgical technique that does not violate the coracoclavicular ligaments, a coracoid graft greater than 25 mm can routinely be harvested for the Latarjet procedure. The inferior glenoid drill hole should typically be placed at least 7 mm from the glenoid margin to avoid lateral overhang.

Secondary rotator cuff dysfunction following total shoulder arthroplasty for primary glenohumeral osteoarthritis: results of a multicenter study with more than five years of follow-up.

BACKGROUND: Secondary rotator cuff dysfunction is a recognized complication following shoulder arthroplasty. We hypothesized that the rate of secondary rotator cuff dysfunction would increase with follow-up and result in less satisfactory clinical and radiographic outcomes. Our aim was to investigate the rate of secondary rotator cuff dysfunction following shoulder arthroplasty for primary osteoarthritis and identify factors associated with the dysfunction. METHODS: Between 1991 and 2003, in ten European centers, 704 total shoulder arthroplasties were performed for primary glenohumeral osteoarthritis. Complete radiographic and clinical follow-up of more than five years was available for 518 shoulders. The diagnosis of secondary rotator cuff dysfunction was made when moderate or severe superior subluxation of the prosthetic humeral head was present on radiographs. Multivariate logistic regression identified factors associated with the development of rotator cuff dysfunction. Kaplan-Meier survivorship analysis was performed, with the end point being secondary rotator cuff failure. Clinical outcome was assessed with use of the Constant score, a subjective assessment of the shoulder, and an evaluation of shoulder motion. RESULTS: At an average of 103.6 months (range, sixty to 219 months) after shoulder arthroplasty, the rate of secondary rotator cuff dysfunction was 16.8%. Survivorship free of secondary cuff dysfunction was 100% at five years, 84% at ten years, and 45% at fifteen years. Duration of follow-up (p < 0.0001), implantation of the glenoid implant with superior tilt (p < 0.001), and fatty infiltration of the infraspinatus muscle (p < 0.05) were risk factors for the development of secondary cuff dysfunction. Patients with secondary rotator cuff dysfunction had significantly worse clinical outcomes (Constant score, subjective assessment, and range of motion; p < 0.0001) and radiographic results (radiolucent line score, radiographic loosening, glenoid component migration; p < 0.0001). CONCLUSIONS: In this study, rates of secondary rotator cuff dysfunction with moderate or severe superior subluxation of the prosthetic humeral head increased with the duration of follow-up and significantly influenced the clinical and radiographic outcome of total shoulder arthroplasty performed for primary glenohumeral osteoarthritis. Preoperative fatty infiltration of the infraspinatus muscle and implantation of the glenoid component with superior tilt were prognostic factors.

Patterns of loosening of polyethylene keeled glenoid components after shoulder arthroplasty for primary osteoarthritis: results of a multicenter study with more than five years of follow-up.

BACKGROUND: The aim of this study was to radiographically analyze the long-term glenoid migration patterns following total shoulder arthroplasty to better understand the factors responsible for loosening. METHODS: Complete radiographic follow-up of more than five years was available for 518 total shoulder arthroplasties performed for primary glenohumeral osteoarthritis with use of an anatomically designed prosthesis with a cemented, all-polyethylene, keeled glenoid component. Radiographs were assessed for humeral head subluxation, periprosthetic radiolucent lines, and shifting of the position of the glenoid component. The type of migration of the glenoid was defined according to the direction of tilt, or as subsidence in the case of medial migration. RESULTS: Definite radiographic evidence of glenoid loosening was observed in 166 shoulders (32%) and was characterized by radiolucency of ≥2 mm over the entire bone-cement interface in thirty shoulders and by a migration of the glenoid component (shift or subsidence) in 136 shoulders. Three predominant patterns of migration of the glenoid component were observed: superior tilting in fifty-two shoulders (10%), subsidence in forty-one shoulders (7.9%), and posterior tilting in thirty-three shoulders (6.4%). Superior tilting of the glenoid was associated with three risk factors: low positioning of the glenoid component, superior tilt of the glenoid component on the immediate postoperative coronal plane radiographs, and superior subluxation of the humeral head (p < 0.05 for all). Subsidence of the glenoid component was associated with the use of reaming to optimize the seating and positioning of the glenoid component (p < 0.001). Posterior tilting of the glenoid component was associated with preoperative posterior subluxation (i.e., a Walch type-B glenoid) and with excessive reaming (p < 0.01 for both). CONCLUSIONS: The three patterns of migration observed in this study underscore the potential importance of the supporting bone beneath the glenoid component. In some shoulders, use of a keel or pegs to provide fixation of a polyethylene component in the absence of good support from subchondral bone may not be sufficient to resist compressive and eccentric forces, resulting in loosening. Preserving subchondral bone may be important for long-term longevity of the glenoid component.

Early results of reverse shoulder arthroplasty in patients with rheumatoid arthritis.

BACKGROUND: Rheumatoid arthritis affecting the shoulder is typically associated with rotator cuff compromise and can also result in severe glenoid erosion. Since reverse shoulder arthroplasty is capable of addressing both rotator cuff disorders and glenoid bone deficiencies, our aim was to evaluate the outcome of reverse shoulder arthroplasty in patients with rheumatoid arthritis and either or both of these associated conditions. METHODS: We performed eighteen primary reverse total shoulder arthroplasties in sixteen patients with rheumatoid arthritis involving the shoulder as well as associated rotator cuff compromise and/or severe erosion of the glenoid bone between 2002 and 2007. Patients were assessed with use of the Constant score, patient satisfaction score, subjective shoulder value, range of shoulder motion, and imaging studies. RESULTS: The mean Constant score improved from 22.5 to 64.9 points at a mean of 3.8 years (range, 2.1 to 7.0 years) postoperatively. The patients were either very satisfied or satisfied with the outcome of the surgery in seventeen of the eighteen shoulders. The mean subjective shoulder value was 68.6% postoperatively. Active forward elevation improved from 77.5° to 138.6°, and external rotation with the arm in 90° of abduction improved from 16.9° to 46.1°. The mean Constant score improved from 28.0 points to 74.3 points in shoulders in which the teres minor muscle was normal before the surgery, and it improved from 20.8 to 54.6 points in shoulders with an atrophic teres minor muscle. Scapular notching was observed in ten of the eighteen shoulders. A fracture involving the acromion, acromial spine, coracoid, or greater tuberosity was observed either intraoperatively or postoperatively in four of the eighteen shoulders. One case of transient axillary nerve injury was noted. There were no cases of dislocation, infection, or component loosening. None of the patients required revision surgery for any reason. CONCLUSIONS: Comparatively good outcomes were observed in the short to intermediate term after reverse shoulder arthroplasty in patients with rheumatoid arthritis. However, surgeons should be aware of the risk of intraoperative and postoperative fractures in this patient group.

Results of a convex-back cemented keeled glenoid component in primary osteoarthritis: multicenter study with a follow-up greater than 5 years.

PURPOSE: We assessed the clinical and radiologic results of a cemented all-polyethylene convex-back keeled glenoid component used with a third-generation prosthesis. METHODS: Between 1996 and 2003, in 4 European centers, 333 shoulder arthroplasties were performed for primary osteoarthritis by use of a cemented all-polyethylene convex-back keeled glenoid component. Kaplan-Meier survivorship analysis was performed, and clinical outcome was assessed with the Constant score, range of motion, and subjective evaluation. RESULTS: At a mean of 89.5 months' follow-up, the Constant score improved from 31.4 to 67.6 points (P < .0001). Active forward elevation improved from 94.9° to 146.6° (P < .0001) and external rotation from 9.0° to 35.3° (P < .0001). Of the patients, 93.5% were either satisfied or very satisfied. The rate of revision for glenoid loosening was 0.6%; however, the rate of radiologic glenoid loosening was 18.9%. Glenoid survival was 99.7% at 5 years and 98.3% at 10 years with endpoint defined as revision surgery for glenoid loosening and 99.7% at 5 years and 51.5% at 10 years with endpoint defined as radiologic loosening. CONCLUSIONS: We showed highly satisfactory clinical outcomes and extremely low rates of revision for glenoid loosening using a cemented convex-back keeled glenoid. There was a concerning rate of radiologic loosening, which only became apparent after 5 years, and this was associated with excessive glenoid reaming. Because radiologic changes are progressive and precede the need for revision, innovations in this field need to report radiologic and clinical results with follow-up of at least 5 to 10 years to prove any superiority.

Proteoglycan 4 downregulation in a sheep meniscectomy model of early osteoarthritis.

Osteoarthritis is a disease of multifactorial aetiology characterised by progressive breakdown of articular cartilage. In the early stages of the disease, changes become apparent in the superficial zone of articular cartilage, including fibrillation and fissuring. Normally, a monolayer of lubricating molecules is adsorbed on the surface of cartilage and contributes to the minimal friction and wear properties of synovial joints. Proteoglycan 4 is the lubricating glycoprotein believed to be primarily responsible for this boundary lubrication. Here we have used an established ovine meniscectomy model of osteoarthritis, in which typical degenerative changes are observed in the operated knee joints at three months after surgery, to evaluate alterations in proteoglycan 4 expression and localisation in the early phases of the disease. In normal control joints, proteoglycan 4 was immunolocalised in the superficial zone of cartilage, particularly in those regions of the knee joint covered by a meniscus. After the onset of early osteoarthritis, we demonstrated a loss of cellular proteoglycan 4 immunostaining in degenerative articular cartilage, accompanied by a significant (p < 0.01) decrease in corresponding mRNA levels. Early loss of proteoglycan 4 from the cartilage surface in association with a decrease in its expression by superficial-zone chondrocytes might have a role in the pathogenesis of osteoarthritis.