Prior mood disorder diagnoses do not relate to current mood disorder symptoms or patient-reported disease severity in rotator cuff patients.

BACKGROUND: Surgery for rotator cuff syndrome does not always produce symptom improvement. Biological factors may explain some symptoms, but mood disorder symptoms may also contribute. The purpose of this study is to examine the interaction between disease severity, prevalence of mood disorder diagnoses, and current mood disorder symptoms in preoperative rotator cuff patients. METHODS: A prospective cohort of patients aged 35-75 years with unilateral rotator cuff disease awaiting surgery participated. Demographics, psychiatric history, the Hospital Anxiety & Depression Scale, and the Western Ontario Rotator Cuff index were collected. Descriptive and univariate statistical testing was performed. RESULTS: Of 140 participants (75M:65W) aged 55 ± 8 years, 34 reported a prior diagnosis of a mood disorder. There was a moderate positive relationship between disease severity and current depression and anxiety scores. Women were more likely to carry a diagnosis of a mood disorder, but there were no differences in current symptom levels between genders. No differences were found in patient-reported outcome measure scores between patients with and without a mood disorder diagnosis. DISCUSSION: Current mood disorder symptoms were associated with greater disease severity, whereas the presence of a past mood disorder diagnosis was not. Awareness of this relationship may reduce bias about past mood disorder diagnoses during decision-making.

Patient gender and rotator cuff surgery: are there differences in outcome?

BACKGROUND: Although rotator cuff syndrome is common and extensively studied from the perspective of producing healed tendons, influence of gender on patient-reported outcomes is less well examined. As activity and role demands may vary widely between men and women, clarity on whether gender is an important factor in outcome would enhance patient education and expectation management. Our purpose was to determine if differences exist in patient-reported outcomes between men and women undergoing rotator cuff surgery. METHODS: One hundred forty-eight participants (76 W:72 M) aged 35-75 undergoing surgery for unilateral symptomatic rotator cuff syndrome were followed for 12 months after surgery. Demographics, surgical data, and the Western Ontario Rotator Cuff (WORC) scores were collected. Surgery was performed by two fellowship-trained shoulder surgeons at a single site. RESULTS: There were no gender-based differences in overall WORC score or subcategory scores by 12 months post-op. Pain scores were similar at all time points in men and women. Women were more likely to have dominant-arm surgery and had smaller rotator cuff tears than men. Complication rates were low, and satisfaction was high in both groups. CONCLUSION: Patient gender doesn't appear to exert an important effect on patient-reported rotator cuff outcomes in this prospective cohort. Further work examining other covariates as well as the qualitative experience of going through rotator cuff repair should provide greater insight into factors that influence patient-reported outcomes.

Management of patients with hip fracture receiving anticoagulation: What are we doing in Canada?

BACKGROUND: Direct oral anticoagulants (DOACs) are rapidly replacing warfarin for therapeutic anticoagulation; however, many DOACs are irreversible and may complicate bleeding in emergent situations such as hip fracture. In this setting, there is a lack of clear guidelines for the timing of surgery. The purpose of this study was to evaluate the current practices of Canadian orthopedic surgeons who manage patients with hip fracture receiving anticoagulation. METHODS: In January-March 2018, we administered a purpose-specific cross-sectional survey to all currently practising orthopedic surgeons in Canada who had performed hip fracture surgery in 2017. The survey evaluated approaches to decision-making and timing of surgery in patients with hip fracture receiving anticoagulation. RESULTS: A total of 280 surgeons representing a mix of academic and community practice, seniority and fellowship training responded. Nearly one-quarter of respondents (66 [23.4%]) were members of the Canadian Orthopaedic Trauma Society (COTS). Almost three-quarters (206 [73.6%]) felt that adequate clinical guidelines for patients with hip fracture receiving anticoagulation did not exist, and 177 (61.9%) indicated that anesthesiology or internal medicine had a greater influence on the timing of surgery than the attending surgeon. A total of 117/273 respondents (42.9%) indicated that patients taking warfarin should have immediate surgery (with or without reversal), compared to 63/270 (23.3%) for patients taking a DOAC (p < 0.001). Members of COTS were more likely than nonmembers to advocate for immediate surgery in all patients (p < 0.05). CONCLUSION: There is wide variability in Canada in the management of patients with hip fracture receiving anticoagulation. Improved multidisciplinary communication, prospectively evaluated treatment guidelines and focus on knowledge translation may add clarity to this issue. LEVEL OF EVIDENCE: IV.

Rotator cuff repair techniques: Current concepts.

Arthroscopic rotator cuff repair is being performed by an ever-increasing number of surgeons. With an ageing population and growing patient expectations it is crucial that clinical outcomes are optimised. Anatomical reduction of the tendon back to its footprint with minimal tension contributes to this, but this can only be achieved if key biomechanical factors are taken into consideration. In this review of the technical aspects of a rotator cuff repair, we focus on: (1) patient positioning, (2) biomechanical principles, (3) optimal visualisation, and (4) repair techniques for both anterior and postero-superior tears.

Intersection of catastrophizing, gender, and disease severity in preoperative rotator cuff surgical patients: a cross-sectional study.

HYPOTHESIS AND BACKGROUND: Surgical outcomes are dependent on multiple clinical and patient factors. One patient factor is pain catastrophizing, which is associated with poorer outcomes in other surgical populations. Our purpose was to examine relationships between gender, patient-reported disease severity, and catastrophizing in patients in whom rotator cuff surgery is planned. We hypothesized that patients with more catastrophizing would report greater disease severity. METHODS: Patients undergoing surgery for unilateral symptomatic rotator cuff disease aged 35 to 75 years were prospectively evaluated. Data collected included demographic characteristics; imaging characteristics; range of motion; and Western Ontario Rotator Cuff Index (WORC), Pain Catastrophizing Scale (PCS), and Short Form 36 scores. RESULTS: A total of 156 patients (87 men and 69 women) aged 54 ± 8 years participated. The mean WORC score was similar between men and women (1286 ± 343 vs. 1327 ± 370, P = .38). The mean PCS score was 14.7 ± 10.6 for men and 17.9 ± 12.4 for women (P = .08). A moderate positive correlation was found between the WORC and PCS scores (r = 0.59, P < .001). Women had poorer WORC-Lifestyle subscale scores (P = .012). Range of motion, Short Form 36 scores, and tear severity were not related to measures of either the WORC or PCS. DISCUSSION AND CONCLUSIONS: The direct relationship between the WORC and PCS scores is consistent with research in other patient populations. Contrary to other work, no gender-based PCS score differences were observed. Differences on the WORC-Lifestyle subscale suggest that women may experience greater functional impacts to specific lifestyle elements than men. Catastrophizing is related to patient-reported disease severity in preoperative rotator cuff patients. Further research will clarify whether this relationship leads to poorer outcomes following surgery.

Surgeon identification of pain catastrophizing versus the Pain Catastrophizing Scale in orthopedic patients after routine surgical consultation

Background: A high level of pain catastrophizing has negative influences on outcomes in many surgical disciplines. Our purpose was to determine whether surgeons are able to accurately identify high catastrophizing in orthopedic patients after routine clinical consultation. Methods: In this prospective study, English-literate patients aged 18 years or older were assessed by 1 of 11 orthopedic surgeons. Patients completed the Pain Catastrophizing Scale (PCS), and the surgeon rated each patient as having a high or low level of catastrophizing after the clinical encounter. We calculated accuracy and agreement of surgeon assessment with the PCS at a cut-off score of 30 (score ≥ 30 = high level of catastrophizing) and used multivariate testing to determine whether patient age or sex, surgeon experience or subscores of the PCS (rumination, magnification and helplessness) influenced surgeon accuracy. Results: Among 203 patients (109 women and 94 men), the mean PCS score was 18.4 (standard deviation 12.9), with no sex difference and no significant correlation to patient age. Of the 40 patients who scored 30 or more on the PCS, 22 (55%) were not identified as having high levels of catastrophizing by their surgeon. Accuracy was 0.72, and agreement was 0.2. Female patients were more likely than male patients to be identified as high catastrophizing regardless of PCS score (odds ratio 2.0, 95% confidence interval 1.04­4.0). Conclusion: Surgeons were not able to accurately identify patients with high levels of pain catastrophizing during routine initial consultation. In considering which patients may most benefit from interventions to improve coping and reduce catastrophizing, explicitly measuring pain catastrophizing will be required.

Contexte: Un niveau élevé de dramatisation face à la douleur a une influence négative sur les résultats dans plusieurs disciplines chirurgicales. Notre objectif était de déterminer si les chirurgiens orthopédistes sont capables d'identifier avec précision un niveau élevé de dramatisation de la douleur chez les patients après une consultation clinique de routine. Méthodes: Au cours de cette étude prospective, des patients capables de communiquer en anglais âgés de 18 ans ou plus ont été évalués par un de 11 chirurgiens orthopédistes. Les patients ont répondu au questionnaire PCS (Pain Catastrophizing Scale), une échelle de mesure de la dramatisation face à la douleur, et après la consultation clinique, le chirurgien assignait à chaque patient un niveau faible ou élevé de dramatisation. Nous avons calculé la justesse et la concordance de l'évaluation du chirurgien avec le score PCS, avec un score seuil de 30 (score ≥ 30 = niveau élevé de dramatisation) et utilisé un test multivarié pour déterminer si l'âge ou le sexe, l'expérience du chirurgien ou certaines sous-échelles de la PCS (rumination, amplification et sentiment d'impuissance) influaient sur le jugement du chirurgien. Résultats: Sur 203 patients (109 femmes et 94 hommes), le score PCS moyen a été de 18,4 (écart-type 12,9), sans différence liée au sexe ni corrélation significative avec l'âge des patients. Sur les 40 patients ayant obtenu un score de 30 ou plus à l'échelle PCS, 22 (55 %) n'ont pas été identifiés comme présentant des niveaux élevés de dramatisation par les chirurgiens. La précision a été de 0,72, et la concordance de 0,2. Les patientes étaient plus susceptibles que les patients d'être identifiées comme présentant un niveau élevé de dramatisation, indépendamment du score à l'échelle PCS (rapport des cotes 2,0, intervalle de confiance à 95 % 1,04­4,0). Conclusion: Les chirurgiens ont été incapables d'identifier avec précision les patients présentant des niveaux élevés de dramatisation face à la douleur durant la consultation initiale de routine. Pour savoir quels patients sont plus susceptibles de bénéficier d'interventions visant à améliorer leurs capacités d'adaptation et réduire la dramatisation, il faudra des mesures précises du niveau de dramatisation face à la douleur.

Can pain catastrophizing be changed in surgical patients? A scoping review

Background: Catastrophizing, a coping style characterized by an exaggerated negative affect when experiencing or anticipating pain, is an important factor that adversely affects surgical outcomes. Various interventions have been attempted with the goal of reducing catastrophizing and, by extension, improving treatment outcomes. We performed a systematic review to determine whether catastrophizing can be altered in surgical patients and to present evidence for interventions aimed at reducing catastrophizing in this population. Methods: Using a scoping design, we performed a systematic search of MEDLINE and Embase. Studies reporting original research measuring catastrophizing, before and after an intervention, on the Pain Catastrophizing Scale (PCS) or Coping Strategies Questionnaire (CSQ) were selected. Studies were assessed for quality, the nature of the intervention and the magnitude of the effect observed. Results: We identified 47 studies that measured the change in catastrophizing score following a broad range of interventions in surgical patients, including surgery, patient education, physiotherapy, cognitive behavioural therapy, psychologist-directed therapy, nursing-directed therapy and pharmacological treatments. The mean change in catastrophizing score as assessed with the PCS ranged from 0 to ­19, and that with the CSQ, from +0.07 to ­13. Clinically important changes in catastrophizing were observed in 7 studies (15%). Conclusion: Catastrophizing was observed to be modifiable with an intervention in a variety of surgical patient populations. Some interventions produced greater reductions than others, which will help direct future research in the improvement of surgical outcomes.

Contexte: Le catastrophisme est un mode d'adaptation caractérisé par un affect démesurément négatif chez la personne qui éprouve ou s'attend à éprouver de la douleur et c'est un facteur important qui peut influer négativement sur les résultats chirurgicaux. Diverses interventions ont été tentées pour atténuer le catastrophisme et par extension, améliorer les résultats des traitements. Nous avons procédé à une revue systématique afin de déterminer s'il est possible de modifier le catastrophisme chez les patients de chirurgie et présenter des données probantes concernant les interventions visant à atténuer le catastrophisme chez cette population. Méthodes: En utilisant un plan de délimitation de la portée, nous avons procédé à une interrogation systématique de bases de données MEDLINE et Embase. Les études portant sur des recherches originales d'évaluation du catastrophisme, avant et après une intervention, au moyen de l'échelle PCS (Pain Catastrophizing Scale) ou du questionnaire CSQ (Coping Strategies Questionnaire) ont été sélectionnées et elles ont été évaluées aux plans de la qualité, de la nature des interventions et de l'ampleur de l'effet observé. Résultats: Nous avons recensé 47 études qui ont mesuré un changement au score du catastrophisme après un vaste éventail d'interventions chez des patients de chirurgie, notamment : chirurgie, enseignement au patient, physiothérapie, thérapie cognitivocomportementales, thérapie sous la supervision d'un psychologue, thérapie sous la supervision du personnel infirmier et traitements pharmacologiques. Le changement moyen au score du catastrophisme évalué à l'aide de l'échelle PCS était de 0 à ­19, et à l'aide du questionnaire CSQ, de 0,07 à ­13. Des changements cliniquement importants du catastrophisme ont été observés dans 7 études (15 %). Conclusion: Le catastrophisme s'est révélé modifiable à l'aide d'interventions chez divers types de patients de chirurgie. Certaines interventions ont généré des réductions plus marquées, ce qui guidera la recherche future pour améliorer les résultats chirurgicaux.

Intermediate outcomes of ulnar head arthroplasty.

PURPOSE: To determine the survivorship and clinical outcomes of ulnar head arthroplasty. METHODS: The study design included a review of medical records and clinical assessment of all patients who had an ulnar head arthroplasty more than 2 years previously. Survivorship of 79 implants in 74 patients was determined. Forty-seven of these patients participated in a clinical review using the Patient Examination Measure, Patient-Related Wrist Examination, Wrightington Wrist Score, and EQ5D to measure outcomes. Analysis of outcomes was performed for diagnostic subgroups (inflammatory arthritis, posttraumatic, osteoarthritis/impingement, and other), primary versus revision surgery, and whether the procedure was performed for ulnar stump instability (related to either a previous Darrach or Sauvé-Kapandji procedure). RESULTS: The 5- and 15-year survival of the implants was 90% for both, with mean follow-up of 7 ± 4 years. Mean age at surgery was 50 ± 13 years (range, 24-76). Mean range of motion was within the functional range and grip strength was 67% that of the contralateral side. Patient satisfaction was generally high, but outcomes scores indicated substantial residual disability. Overall scores were 41 for the Patient Examination Measure, 52 for the Patient-Related Wrist Examination, and 70 for the WWS. Patients in the "other" category had the worst scores for all measures. Patients with prior wrist surgery had poorer outcomes than those for whom the arthroplasty was a primary procedure. Patients with posttraumatic diagnoses had worse EQ5D scores and were less likely to recommend the procedure to others. CONCLUSIONS: Ulnar head arthroplasty had good long-term survival and acceptable patient satisfaction. Substantial disability remained in all groups, with the posttraumatic, "other", and revision groups faring worse. Patients should be counseled about the expected outcomes of this specialized procedure as they pertain to the patient's specific situation. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

Reconstructing the interosseous membrane: a technique using synthetic graft and endobuttons.

Reconstruction of the interosseous membrane is an emerging procedure designed to help restore anatomic and biomechanical relationships within the forearm after a longitudinal instability injury. The indication for this reconstruction is proven acute or chronic longitudinal instability of the forearm. This technique uses a synthetic braided graft tied over endobuttons at radial and ulnar tunnels. It can also be combined with other procedures such as radial head replacement, wafer procedures, and even ulnar shortening osteotomies for comprehensive management of the condition. Early results indicate that this reconstruction can produce clinical improvement in some patients. Further follow-up is required to determine the long-term durability of the construct, but early results are encouraging in a complex patient population.

Landmarks for rotational alignment of the humeral component during elbow arthroplasty.

BACKGROUND: The reference points for rotational orientation of the humeral component during elbow arthroplasty typically are on the articular surface or the humeral epicondyles. With bone loss, these landmarks may be compromised. Our purpose was to assess whether the flat posterior humeral cortex proximal to the olecranon fossa is a reliable landmark with which to orient the humeral component during elbow arthroplasty. METHODS: Fifty cadaveric elbows (mean age [and standard deviation] at the time of death, 73 ± 12 years) underwent computed tomography (CT) scans. The flexion-extension axis (FEA) was determined by sphere-fitting the capitellar surface and circle-fitting the narrowest portion of the trochlea. The posterior humeral cortical line (PCL) was drawn on the flat posterior humeral cortex proximal to the olecranon fossa. The transepicondylar axis (TEA) was determined by a line between the most prominent points on the epicondyles. The angles between the PCL and FEA and the TEA and FEA were calculated and were compared by using two-tailed t tests. RESULTS: The PCL was externally rotated by a mean (and standard deviation) of 14.0° ± 4.2° (p < 0.001) relative to the FEA (males: 12.6° ± 3.6°, females: 16.4° ± 5.2°; p = 0.002). The TEA was externally rotated by a mean of 2.8° ± 3.5° (p < 0.001) relative to the FEA (males: 2.7° ± 3.4°, females: 2.6° ± 3.7°; p = 0.96). The intraobserver and interobserver reliability was >0.98 for the capitellar and trochlear centers, while the cumulative intraobserver and interobserver reliability was 0.8 and 0.5 for the FEA-PCL angle and 0.4 and 0.3 for the FEA-TEA angle. CONCLUSIONS: The posterior humeral cortex is a reproducible landmark that is externally rotated with respect to the flexion-extension axis of the distal part of the humerus. The surgeon must be aware of the need for an internal rotation correction factor and consider the influence of the patient's sex on this correction when using the posterior humeral cortex as a landmark to avoid humeral component malrotation. CLINICAL RELEVANCE: While the PCL is better than the TEA as a reference point, neither is able to accurately identify the FEA because of considerable normal variation. Future studies are needed to evaluate the effectiveness of computer-assisted techniques or a preoperative CT scan of the contralateral, unaffected elbow in identifying rotational landmarks for the elbow undergoing arthroplasty.

Capitellar excision and hemiarthroplasty affects elbow kinematics and stability.

INTRODUCTION: Capitellar hemiarthroplasty is proposed as a reconstructive option for isolated capitellar deficiency, but there is limited data on its effect on elbow biomechanics. This study assessed the effect of capitellar excision with and without replacement on elbow kinematics and stability, and evaluated 2 different implant surface shapes. MATERIALS AND METHODS: Ten cadaveric arms were tested with an upper extremity joint simulator. Each arm underwent computer tomography scanning for implant sizing and computer-assisted implantation. Kinematic data were obtained using an electromagnetic tracking system during elbow flexion, with the arm oriented in the valgus, varus, and vertical positions. Implants were placed through an extended lateral epicondylar osteotomy using computer-assisted techniques. A repeated-measures design compared 2 implants (anatomical and spherical) to the native capitellum control and capitellar excision states. Outcomes were maximum varus-valgus laxity and rotation of the ulna with respect to the humerus. RESULTS: Excision of the capitellum increased the varus-valgus laxity up to 3.1° in active elbow flexion, with the forearm in pronation but not in supination. Both capitellar implant designs maintained normal varus-valgus laxity in both active and passive elbow flexion. Excision of the capitellum increased external ulnar rotation during active flexion in the vertical and valgus positions up to 1.5°, while both implants restored normal ulnar rotation. The kinematics and stability of the elbows were similar for both implant designs. CONCLUSION: The capitellum appears to have a role as a valgus and external rotational stabilizer of the ulnohumeral joint. This instability was corrected by both designs of capitellar hemiarthroplasty.

A morphological analysis of the humeral capitellum with an interest in prosthesis design.

INTRODUCTION: Although interest in capitellar arthroplasty is increasing, the morphology of the capitellum has not been fully characterized. Our purpose was to quantify the anthropometric features of the capitellum with an interest in arthroplasty design. We hypothesized that the shape is more complex than originally believed, and cannot be accurately modeled as a spherical structure. METHODS: Fifty cadaveric human elbows underwent helical computer tomography scans. After reconstruction and establishment of a coordinate system for the distal humerus, circle-fits were applied to each of the 1-mm-thick slices. Sagittal radii of curvature were calculated every 10° of flexion around each circle (0-130° of flexion). A single transverse radius was calculated at 60° of flexion. The surface of the capitellum was described by sagittal and transverse radii of curvature and the footprint by height and width. These pairs of parameters were correlated to determine their strength of association. RESULTS: The average height was 23.2 ± 2.9 mm (range, 18.3-29.5), while the average width was 13.9 ± 2.3 (range, 9-19). The sagittal radius of curvature was 11.6 ± 1.4 mm (range, 8.7-14.8), and the transverse radius was 14.0 ± 3.0 mm (range, 9.6-20.9). Correlations of height and width and sagittal and transverse radii were significant (R = .547, .705) (P < .01). Sagittal and transverse radii and height and width were significantly different (P < .001 for each pair). CONCLUSION: The capitellum does not have a spherical surface or a circular footprint. There is substantial variability in the relationship between the height and width, and between the surface radii, that may be difficult to replicate with an off-the-shelf implant.

Osteochondral lesions of the capitellum do not affect elbow kinematics and stability with intact collateral ligaments: an in vitro biomechanical study.

PURPOSE: Osteochondritis dissecans (OCD) of the capitellum most commonly affects adolescent pitchers and gymnasts, who present with pain and mechanical symptoms. Patients with larger lesions have poorer outcomes, possibly related to increased contact pressures on the surrounding articular surface with or without instability. The purpose of this in vitro study was to determine whether displaced OCD lesions of the capitellum lead to altered kinematics and stability of the elbow. METHODS: We mounted 9 fresh-frozen cadaveric arms in an upper extremity joint testing system, with cables attaching the tendons of the major muscles to motors and pneumatic actuators. An electromagnetic receiver on the ulna enabled quantification of the kinematics of the radius and ulna with respect to the humerus. We used 3-dimensional computed tomography scans and computer-assisted techniques to navigate sequential osteochondral defects ranging in size from 12.5% to 100% of the capitellum. The arms were subjected to active and passive flexion in both the vertical and valgus positions with the forearm in both pronation and supination. RESULTS: We found no significant differences in valgus angulation or ulnar rotation between any of the OCD lesions and the intact elbow during flexion, regardless of arm position or forearm rotation. CONCLUSIONS: Osteochondritis dissecans lesions of the capitellum, both small and large, did not alter the ulnohumeral kinematics and stability with intact collateral ligaments. Therefore, excision of unfixable osteochondral fragments of the capitellum in the setting of intact collateral ligaments can be considered without the risk of creating instability.

Effect of coronal shear fractures of the distal humerus on elbow kinematics and stability.

BACKGROUND: Coronal shear fractures of the distal humerus can include some or all of the cartilaginous and bony surface. Fixation is preferred, but severe comminution, nonunion, and avascular necrosis may mandate excision. The amount of distal humerus that is safe to excise is unknown. This study examined the effect of excision of the capitellum and trochlea on elbow kinematics and stability with intact collateral ligaments. METHODS: Eight cadaveric arms were mounted in an upper extremity joint testing system. Electromagnetic receivers on the radius and ulna enabled quantification of ulnohumeral and radiocapitellar kinematics. The distal humeral articular surface was sequentially excised to replicate clinically relevant coronal shear fractures, leaving the collateral ligaments undisturbed. The arms underwent simulated active flexion in vertical and valgus-loaded positions, and passive forearm rotation in the vertical position. RESULTS: In the vertical position, sequential excision of the articular surface increased valgus angulation during active flexion (P < or = .04), and excision of the entire articular surface increased ulnar external rotation compared to the intact elbow (P < or = .02). In the valgus position, excisions involving the trochlea increased valgus angulation for active flexion (P < or = .04). The radial head moved distal, posterior, and medial on the capitellum with some or all of the trochlea excised (P < or = .02). DISCUSSION: While the capitellum alone does not contribute to elbow stability, the trochlea has an important role. Excision of the trochlea resulted in multiplanar instability of the ulnohumeral and radiocapitellar joints. Therefore, excision of an irreparable capitellum fracture may be considered if collateral ligaments are intact, while excision of some or all of the trochlea may not.

Comparing the fixation of a novel hollow screw versus a conventional solid screw in human sacra under cyclic loading.

STUDY DESIGN: The loosening rates of two monocortical pedicle screw designs (hollow and solid) were compared in a cadaveric sacrum model subjected to cyclic loading. OBJECTIVE: To determine if a hollow screw would be more resistant to loosening than a solid pedicle screw when placed into the pedicles of S1 and tested under stair-cased cyclic loading. SUMMARY OF BACKGROUND DATA: Screw loosening is a clinical problem for lumbosacral fusions. No previous literature has evaluated the use of a monocortical hollow screw within the sacrum; however, in other vertebral bodies, results of using this screw have been varied. METHODS: Seven fresh-frozen cadaveric sacra were thawed and stripped of soft tissues. Solid and hollow screws were inserted contralaterally into the pedicles of S1. A materials testing machine applied alternating flexion and extension bending moments at 1 Hz, to each screw independently, via a standard connecting rod. Flexion moments were applied starting at 0.5 Nm and increased by 0.5 Nm after every 1000 cycles until the screw had visibly failed. Extension moments were maintained at 0.5 Nm. Screw rotation (flexion) relative to the sacrum was recorded using a custom optical tracking system, and analyzed using 2-way repeated measures analyses of variances and post hoc Student-Newman-Keuls tests (alpha = 0.05). RESULTS: Screw rotation tended to gradually increase to six degrees, after which the screw was grossly loose. Overall, the hollow screw required fewer loading cycles (P = 0.004) and less applied moment (P = 0.003) to achieve the same magnitude of screw rotation as the solid screw. To achieve 6 degrees of screw rotation, the number of loading cycles were 6301 +/- 2161 and 11151 +/- 4221 for hollow and solid screws, respectively. The corresponding applied moments were 3.5 +/- 1.0 Nm and 5.8 +/- 2.0 Nm. CONCLUSION.: The novel hollow screw was less resistant to loosening when compared with a conventional solid pedicle screw in this sacral model under cyclic loading.