Factors Affecting the Second Complete Atypical Femoral Fracture after the First Atypical Fracture.

OBJECTIVES: Atypical femoral fracture (AFF) is an atypical low-energy subtrochanteric and diaphyseal femoral fracture. Even if bone fusion is achieved in patients with AFF, the risk of AFF in the contralateral femur must be considered. This study aimed to investigate the factors affecting complete AFF in the contralateral femur and conservatively treated incomplete AFF. SUBJECT AND METHODS: Radiographs of 111 femurs in 104 AFF cases were examined, and the femurs were classified as follows: 85 contralateral femurs with complete AFF; 18 contralateral femurs with incomplete AFF; 8 femurs with incomplete AFF without surgical treatment. Various patients' clinical data were collected, and we investigated the factors affecting the second complete AFF. RESULTS: Complete fractures occurred in 10 (9.7%) of 103 femurs without incomplete AFF at the first visit and in 3 (37.5%) of 8 femurs with incomplete AFF. The Kaplan-Meier curve revealed that lateral cortical bone thickening and thigh pain were associated with significantly poorer prognoses (p = 0.026 and p = 0.013, respectively). Multivariate analyses revealed that eldecalcitol usage after AFF onset (p = 0.0094) and previous use of bisphosphonate or denosumab (p = 0.0126) were protective factors for second complete AFF and that the presence of thigh pain (p = 0.0134) was a risk factor for second complete AFF. CONCLUSIONS: Eldecalcitol administration after bone union of first AFF may prevent AFF recurrence. In addition, painful incomplete AFF has a high risk of developing a complete fracture.

Comparison of the Continuation Rate of Twice-Weekly and Weekly Teriparatide Administration in a Rural Area.

Teriparatide plays an important role in the treatment of patients with severe osteoporosis; however, it is meaningless if patients cannot continue. In recent years, the use of a twice-weekly auto-injector teriparatide preparation has become possible. However, its continuation rate and the factors affecting it have not been adequately investigated. Therefore, this study aimed to examine the continuation rate of twice-weekly teriparatide and the factors affecting it. This retrospective study included 143 patients who were administered teriparatide weekly (65 patients) or twice-weekly (78 patients) in a rural hospital. Patient information, such as age, the distance between the hospital and home, family structure, past osteoporosis treatment and fracture, adverse events, and period of teriparatide continuation, were collected. We compared the differences in continuation rates between the twice-weekly and the weekly groups using the Kaplan-Meier curves, and we examined factors influencing teriparatide discontinuation using multivariate analyses. The 12- and 24-month continuation rates of twice-weekly administration of teriparatide were 79.5% and 61%, respectively. The twice-weekly group showed a significantly higher continuation rate (P < 0.0001). The multivariate analyses showed that older age and adverse events were identified as risk factors negatively influencing teriparatide continuation (P = 0.0237 and P < 0.0001, respectively). On the other hand, twice-weekly teriparatide was shown to reduce the risk of discontinuation (P = 0.0043). The twice-weekly teriparatide has a considerably higher continuation rate than the weekly teriparatide. Weekly preparation, older age, and adverse event were identified as risk factors negatively influencing teriparatide continuation.

Evaluation of the Nature and Etiologies of Risk Factors for Diaphyseal Atypical Femoral Fractures.

OBJECTIVES: Differences in mechanisms of subtrochanteric and diaphyseal atypical femoral fractures (AFFs) are speculated in studies that analyzed differences in the patients' background. However, the etiologies of each type of AFF have not been studied in detail. This study aimed to investigate the nature and etiologies of the risk factors for diaphyseal AFFs. MATERIALS AND METHODS: Eighty consecutive Japanese patients with 91 diaphyseal AFFs (AFF group) and 110 age-matched women with osteoporosis (non-AFF control group) were included. Their clinical data were compared; factors affecting AFFs were investigated, and the etiologies of the risk factors for diaphyseal AFFs were examined. RESULTS: Multivariate analysis revealed that femoral serrated changes, bisphosphonate or denosumab usage, and lateral and anterior femoral curvatures were risk factors for diaphyseal AFFs (p < 0.0011, p = 0.0137, and p < 0.0001, respectively). Multivariate analyses revealed that serrated changes and low serum 25(OH)D levels affected the lateral curvature (p = 0.0088 and 0.0205, respectively), while serrated changes affected the anterior curvature (p = 0.0006), each significantly affected the femoral curvature. High serum calcium (Ca) levels, lateral femoral curvature, and anterior femoral curvature were predictors of serrated changes (p = 0.0146, 0.0002, and 0.0098, respectively). CONCLUSION: Risk factors for diaphyseal AFFs were bone resorption inhibitor usage, a strong femoral curvature, and serrated changes. Low serum 25(OH)D levels and serrated changes are risk factors for lateral curvature, while a high serum Ca level is a risk factor for serrated changes.

Evaluation of factors affecting the occurrence of second atypical fracture after bone union of the first atypical fracture.

PURPOSE: Teriparatide is sometimes used in the treatment of atypical femoral fracture (AFF). Even if bone union is achieved, orthopedic physicians must consider the risk of relapse. This study aimed to investigate the factors affecting AFF recurrence, and to determine the appropriate treatment for osteoporosis after bone union. METHODS: One hundred thirty-one consecutive AFFs in 113 Japanese patients were included. Eleven patients had AFF in the unaffected limb (9 patients) after the first AFF or re-fracture at the original fracture site (2 patients) after bone union of the first AFF was confirmed. We divided all patients into two groups: the second fracture group (22 AFFs in 11 patients) and non-second fracture group (109 AFFs in 102 patients). We compared clinical information between the 2 groups and investigated the factors affecting AFF recurrence using the Student t-, Welch t-, and chi-square tests. RESULTS: Although there was no significant difference in clinical characteristics between the 2 groups, multivariate analysis of factors associated with AFF recurrence identified short duration of treatment with teriparatide and active vitamin D3 (p = 0.0408 and 0.0366, respectively) as risk factors. Even in the analysis excluding subtrochanteric AFF, short periods of teriparatide and active vitamin D3 administration were observed as risk factors (p = 0.0484 and 0.0346, respectively). CONCLUSION: The administration of teriparatide for as long as possible after occurrence first AFF and the use of active vitamin D3 after completion of teriparatide therapy may be the most effective strategy to prevent the recurrence of AFF.

Factors affecting continuation of weekly teriparatide administration in rural areas.

INTRODUCTION: Although teriparatide plays an important role in the treatment of patients with severe osteoporosis, it is meaningless if patients cannot continue. There have been few reports of studies evaluating factors affecting the continuation rate of weekly teriparatide; moreover, no study has investigated the relationship between the distance to travel to the hospital and continuation rate. Therefore, we examined the continuation rate of weekly teriparatide and factors that affect this rate. MATERIALS AND METHODS: This retrospective study included 73 patients who were administered weekly teriparatide in a rural hospital. Patient information, including the age, sex, distance between the hospital and home, family structure, place of introduction, reason for the start of teriparatide administration, past osteoporosis treatment and fracture, side effects, and period of teriparatide continuation, was collected. We examined factors influencing weekly teriparatide continuation. RESULTS: The continuation rate of weekly teriparatide was 22.7%. The Kaplan-Meier curves for the two groups regarding the place of introduction and side effects showed significant differences (P = 0.0158 and P = 0.0309, respectively). In the multivariate analyses to investigate factors associated with teriparatide continuation, an older age, starting administration while hospitalized, and side effects were identified as risk factors negatively influencing continuation (P = 0.0280, P = 0.0222, and P = 0.0095, respectively). On the other hand, the number of family members and distance between our hospital and home did not affect teriparatide continuation. CONCLUSION: An older age, starting administration while hospitalized, and side effects were identified as risk factors negatively influencing teriparatide continuation.

Foot pressure pattern, hindfoot deformities, and their associations with foot pain in individuals with advanced medial knee osteoarthritis.

This survey clarified foot pressure patterns and hindfoot deformities in individuals with advanced knee osteoarthritis (OA) and analyzed their associations with foot pain. Sixty-four individuals with unilateral knee OA who underwent total knee arthroplasty (TKA) were divided into the following groups: no foot pain (n=26; men:women, 4:22; mean age, 73.7 years), foot pain resolved after TKA (12; 2:10; 75.8), and foot pain remaining after TKA (26; 4:22; 74.7). Elderly individuals without pain or deformity in either knee (54; 10:44; 74.3) were controls. Navicular height ratio of the medial longitudinal arch, leg-heel angle, and partial foot pressure as the percentage of body weight (%PFP) were calculated.%PFPs of the medial and lateral heel regions before TKA were significantly lower for the no foot pain group than for controls. One year after TKA, %PFP improved significantly. In the foot pain resolved group, before TKA, the leg-heel angle was significantly higher, and%PFPs of the medial and lateral heel regions and navicular height ratio before TKA were significantly lower than those of controls. One year after TKA, all parameters improved significantly. In the foot pain remaining group, similar abnormalities were observed before TKA; however, significant improvement was only observed for%PFP of the medial heel region 1year after TKA. More than half of the patients with advanced knee OA had foot pain. This improved in approximately one-third, 1year after TKA. Hindfoot deformities are probably associated with foot pain in individuals with advanced knee OA.

The effect of teriparatide to alleviate pain and to prevent vertebral collapse after fresh osteoporotic vertebral fracture.

Vertebral fracture is often seen in osteoporotic patients. Teriparatide is expected to promote bone union. Therefore, we evaluated the action of vertebral collapse prevention by administering teriparatide to vertebral fracture patients. Thirty-four patients with fresh vertebral fracture (48 vertebrae) participated in this study. They were administered either teriparatide (daily 20 µg/day or weekly 56.5 µg/week) or risedronate (17.5 mg/week): ten patients (20 vertebrae) received teriparatide daily (Daily group), 11 patients (15 vertebrae) received teriparatide weekly (Weekly group), and 13 patients (14 vertebrae) received risedronate (RIS group). We compared some laboratory examination items, visual analogue scale (VAS) of low back pain, vertebral collapse rate and local kyphotic angle, and the cleft frequency. In addition, we evaluated 22 vertebral fracture patients (24 vertebrae) who did not take any osteoporotic medicines (Control group). There was no significant difference in any of the scores at the start of treatment. At 8 and 12 weeks after the initial visit, VAS scores in the Daily and Weekly groups were significantly lower than in the RIS group (p < 0.05). At 8 and 12 weeks, the vertebral collapse rate and local kyphotic angle in the Daily group were significantly lower than in the RIS and Control groups (p < 0.01 and p < 0.05, respectively), and those in the Weekly group were significantly lower than in the Control group (p < 0.05). The cleft frequency in the Daily group was significantly lower than in the RIS group (p < 0.05). Teriparatide is promising for the prevention of vertebral collapse progression after vertebral fracture.

Occurrence of vertebral fracture more closely associated with decreased anteroposterior than lateral lumbar bone mineral density.

OBJECTIVES: While it has been pointed out that an anteroposterior (AP) view of the lumbar spine may lead to overestimation of the bone mineral density (BMD), a lateral view is expected lead to the early detection of BMD loss on scanning cancellous bone. Vertebral fracture is often seen in aged osteoporotic patients, and it is important to prevent this fracture. Therefore, we aimed to identify the optimal site for BMD measurement to assess the risk of vertebral fracture. METHODS: Forty-seven female patients with fresh osteoporotic vertebral fracture and BMD measurements were included in this study (Fracture group). As a non-fractured control group, 218 female patients with BMD measurements were enrolled (Control group). We compared BMD values based on AP and lateral views of the lumbar spine from L2 to L4 and the femoral neck. With a lateral view of the lumbar spine, we measured both the total vertebral body and vertebral body center, mainly composed of cancellous bone. RESULTS: BMD of the AP lumbar spine in the Fracture group was significantly lower than in the Control group (P < 0.05). In the subanalyses for comparisons between age-matched fracture and control groups, BMD of only the AP lumbar spine in the Fracture group was significantly lower than in the Control group (P < 0.01). CONCLUSIONS: AP lumbar spine BMD is optimal for assessing vertebral fracture occurrence.

Combined Effect of a Locking Plate and Teriparatide for Incomplete Atypical Femoral Fracture: Two Case Reports of Curved Femurs.

In surgical treatment for atypical femoral fractures (AFFs), reconstruction nail fixation is recommended for both complete and incomplete fractures. Although it has been reported that AFF is affected by many factors, The ASBMR Task Force 2013 Revised Case Definition of AFFs states that a curved femur is often seen in Asian patients. It is sometimes difficult to insert a nail into a femur in incomplete AFF patients with severely curved femurs. We report two incomplete bisphosphonate-related AFF patients with marked femoral curvatures treated by locking plates and teriparatide, showing early bone unions and favorable long-term outcomes.

A case of incomplete atypical femoral fracture with histomorphometrical evidence of osteomalacia.

Roughly half of the femoral fracture patients diagnosed with AFF according to the criteria suggested by a task force of the American Society for Bone and Mineral Research (ASBMR) have not undergone bisphosphonate (BP) therapy. One suspected cause of such fractures is severe bone loss due to osteomalacia, but the pathogenesis remains unknown. We report a case of an 84-year-old woman with AFF not treated by BP therapy, in whom underlying osteomalacia was histologically diagnosed. The involvement of femoral curvature and spino-pelvic malaligment in the fracture in the present case was considered.

Adhesion of gels by silica particle.

In this study, a method for achieving adhesion between two positively charged gels with high mechanical strength was developed. By utilizing a silica particle dispersion as a binder, the gels easily adhered to each other and remained stable for up to 11 days when immersed in aqueous solution. The adhesion force between the two positively charged semi-interpenetrating network gels with the silica particle was measured to be up to approximately 20 kPa, which is around 10 times larger than that with a charged polymer-rich liquid as a cross-linker (approximately 1.5 kPa). It was demonstrated that the adhesion force was a result of two types of interactions: an electrostatic attractive force between the cationic gel surface and hydrogen bonding among the silica particles. In addition, it was shown that the adhesion force was dependent on solution pH, which was attributed to changes in the charge of the silica particles.

High prevalence of abdominal aortic aneurysm in patients with chronic low back pain.

Low back pain (LBP) is one of the most common symptoms in outpatient clinics, and abdominal aortic aneurysm (AAA) is one of the causes of LBP. In the present study, we examined the prevalence of chronic LBP in patients with aortic aneurysm. The study included 23 patients with AAA and 23 patients with thoracic aortic aneurysm (TAA); all of them visited a regional center hospital in Akita, Japan. A total of 207 hypertension patients were also enrolled as a control. Chronic LBP was defined in patients who visited the orthopedic outpatient clinic for the LBP treatment for more than three months. The prevalence of chronic LBP in the AAA group (52.2%) was significantly higher than that in the TAA (17.4%, P < 0.05) or hypertension patients (11.6%, P < 0.01). The rate of a trigger point (TP) injection was significantly higher in the AAA group or the TAA group than that in hypertension patients (P < 0.01, P < 0.05), but there was no significant difference between the AAA and TAA groups. The TP injection represents an injection of local anesthesia to the low back muscles. We also evaluated the involvement of various factors in LBP caused by AAA, such as age, gender, blood pressure, the existence of dissection, and the maximum diameter of AAA, but none of them showed significant relationship to LBP. The prevalence of LBP is high in AAA patients, and doctors who treat chronic LBP should be aware of AAA as a potential cause of LBP.

Trigger finger appearing as gradually increasing digital nerve disorder after surgical treatment.

Trigger finger is a common disease, and operative treatments are often applied for it. Digital nerve injury is one of the complications of this surgical treatment, and paresthesia and sensory disturbance occur early after the operation. This paper presents a case of trigger finger appearing gradually as increasing digital nerve disorder after surgical treatment. In the second surgery, scar tissue covered the palmar MP joint where the A1 pulley had existed before, and palmar digital neurovascular tissue of the ulnar side was found on the inside of the scar. The ulnar digital nerve showed swelling like a neuroma, and bilateral digital nerves existed nearer to the center of the flexor pollicis longus tendon than normal digital nerves. Even when we operate on trigger finger by open release, we should create an appropriate surgical space for observation and be careful of digital nerve injury.

Prevalence of symptomatic and asymptomatic rotator cuff tears in the general population: From mass-screening in one village.

PURPOSE: Rotator cuff tear is the most common shoulder disease in patients with shoulder problems, but its prevalence is not well known. METHODS: We performed a health care check-up of locomotive organs in 664 residents (21.3% of the population) in one village. Ultrasonography on bilateral shoulders was performed in all the participants. RESULTS: One hundred and forty seven out of 664 subjects (22.1%) had full-thickness rotator cuff tears. The prevalence of tear in each decade was 0% in the 20s to 40s, 10.7% in the 50s, 15.2% in the 60s, 26.5% in the 70s, and 36.6% in the 80s. Symptomatic rotator cuff tears accounted for 34.7% of all tears and asymptomatic tears for 65.3%. The prevalence of asymptomatic rotator cuff tears was one-half of all tears in the 50s, whereas it accounted for two-thirds of those over the age of 60. The prevalence of tear was significantly greater in male than in female in the 50s and 60s, but not in the 70s and 80s. CONCLUSION: The prevalence of rotator cuff tear in the general population was 22.1%, which increased with age. Asymptomatic tear was twice as common as symptomatic tear.

Healing processes of the glenoid labral lesion in a rabbit model of shoulder dislocation.

Traumatic dislocation most commonly occurs at the shoulder joint. After an initial dislocation of the shoulder, the labrum is usually detached from the glenoid (Bankart lesion). If this lesion fails to heal, surgical repair is necessary. The purpose of this study was to determine the histological and biomechanical healing process of a simulated Bankart lesion created in rabbits. A labral injury was surgically created in 40 Japanese White rabbits. The labrum was sharply dissected from the glenoid rim simulating a Bankart lesion, and was repositioned without sutures. The joint capsule, the supraspinatus and infraspinatus tendons, and the deltoid were anatomically repaired with sutures. Eight rabbits each were sacrificed at 1, 2, 3, 4, and 5 weeks after the surgery for histological and biomechanical examinations (4 animals each). The histology and biomechanical properties of the normal capsulolabral structure was examined in 8 control rabbits. Inflammatory cell infiltration into the gap between the glenoid and the labrum was noted from 1 week. The gap was covered with fibrous connective tissue accompanied by the collagen fibers by 3 weeks. The healing process was completed histologically by 3 weeks. Biomechanically, the tensile load, which decreased significantly at 1 week, gradually increased and returned to the level of intact shoulder at 4 weeks. At least four weeks are necessary for the healing of the labral injury in rabbits. Considering the difference between humans and rabbits, it seems reasonable to let the patients go back to sports 2 to 3 months after dislocation or surgical repair.

Sarcomere length of torn rotator cuff muscle.

BACKGROUND: Sarcomere length is one of the factors related to the contractile ability of muscle. There is no report about sarcomere length of torn rotator cuff muscles. The purpose of this study was to clarify sarcomere length of torn rotator cuff muscles. MATERIALS AND METHODS: Twenty-eight embalmed cadaver shoulders (14 shoulders with intact rotator cuff and 14 shoulders with full-thickness rotator cuff tears: an isolated tear of the supraspinatus in 3, a combined tear of the supraspinatus and infraspinatus in 4, and a combined tear of the supraspinatus, infraspinatus and subscapularis in 7) were used in this study. Muscle fiber length was measured using a digital caliper. Sarcomere length was measured by laser diffraction method. RESULTS: Muscle fiber lengths of the supraspinatus and infraspinatus (33.0 +/- 6.5 mm and 61.5 +/- 14.0 mm, respectively) in the cuff tear group were significantly shorter than those in the intact cuff group (56.9 +/- 10.1 mm and 74.2 +/- 10.0 mm: P < .001 and P = .010). The sarcomere lengths of these muscles were 3.00 +/- 0.44 microm and 3.12 +/- 0.45 microm in the intact cuff group and 2.90 +/- 0.34 microm and 3.01 +/- 0.34 microm in the cuff tear group. The sarcomere lengths showed no significant difference (P = 0.46 and P = .37). CONCLUSION: The sarcomere lengths of the supraspinatus and infraspinatus with torn tendons were not significantly different from those with intact tendons, although the muscle fiber lengths were significantly shorter with torn tendons.

Effect of an anterior glenoid defect on anterior shoulder stability: a cadaveric study.

BACKGROUND: There have been few biomechanical studies to clarify which size of a glenoid defect is critical. However, those studies have assumed that the defect occurred anteroinferiorly. Recent studies have reported that the defect is located anteriorly rather than anteroinferiorly. Therefore, the effect of the anterior, not anteroinferior, glenoid defect on shoulder stability needs to be investigated. HYPOTHESIS: The anterior glenoid defect would have a similar effect on anterior shoulder stability as that of the anteroinferior glenoid defect. STUDY DESIGN: Controlled laboratory study. METHODS: Eight fresh-frozen cadaveric shoulders were used (mean age, 74 years). The specimen was attached to a shoulder-testing device with the arm in abduction and external rotation. An osseous defect was created stepwise with a 2-mm increment of the defect width. The stability ratio was used to evaluate joint stability. With a 50-N axial force, the translational force applied to the humeral head was measured by a force transducer. RESULTS: The stability ratio without a defect (32% +/- 6%) significantly decreased after creating a 6-mm defect (17% +/- 5%; P = .0001), which was equivalent to 20% of the glenoid length. CONCLUSION: An osseous defect at 3 o'clock with a width that was equal to or greater than 20% of the glenoid length significantly decreased anterior stability. CLINICAL RELEVANCE: The results suggest that reconstruction of the glenoid concavity might be necessary in shoulders with an anterior glenoid defect of at least 20% of the glenoid length.

Three-dimensional ultrasonography of shoulders with rotator cuff tears.

BACKGROUND: It is possible to evaluate the size of rotator cuff tears by ultrasonography (US) or magnetic resonance imaging. However, there are only a few reports on the imaging assessment of the configuration of cuff tears, which could provide important preoperative information that assists performing an optimal anatomical repair. The purpose of this study was to determine quantitatively the reproducibility of three-dimensional US in the assessment of rotator cuff tear configuration. METHODS: Ten embalmed cadaveric shoulders with rotator cuff tears were examined. After resecting the proximal humerus with the rotator cuff, we put it in water and scanned it using high-resolution US with a three-dimensional linear probe. Actual tear lengths and widths were compared with sonographic measurements (Pearson correlation coefficient). By superimposing the real photographic image on the reconstructed three-dimensional image, we calculated the concordance rate (ratio of the concordance area to the tear area). RESULTS: The actual tear length (16.6 +/- 7.1 mm; mean +/- SD) and width (8.4 +/- 4.4 mm) were correlated with the tear length (16.4 +/- 7.5 mm) and width (8.2 +/- 4.4 mm) measured from reconstructed three-dimensional ultrasonograms (r = 0.998 and 0.994, respectively). The mean concordance rate was 91.4%, indicating that almost exactly the same configuration was reconstructed by US. CONCLUSIONS: Three-dimensional US is useful for evaluating the configuration of rotator cuff tears. This is the first report to quantify the similarity between the configuration evaluated by US and the actual configuration. Using this method, we can visualize the configuration of rotator cuff tears preoperatively, facilitating optimal repair design.

Mechanical environment of the supraspinatus tendon: three-dimensional finite element model analysis.

BACKGROUND: We analyzed the mechanical environment of the supraspinatus tendon using a three-dimensional finite element model with the software programs MENTAT and MARC. METHODS: The supraspinatus tendon that attaches to the superior facet was extracted and modeled. The geometric shape of the humeral head was determined from computed tomography images, and the shape of the supraspinatus tendon was determined from magnetic resonance images of the shoulder at 0 degrees of abduction in a healthy 27-year-old man. The distal portion of the humeral head was fixed, and 10 N of tensile force was applied to the proximal end of the tendon. The tensile stress was calculated. RESULTS: The tensile stress was 1.8 MPa for the bursal side and 15.0 MPa for the articular side of the anterior portion of the supraspinatus tendon. The intensity was 0 MPa for the bursal side and 4.5 MPa for the articular side of the middle portion of the tendon. The intensity was 0.1 MPa for the bursal side and 5.2 MPa for the posterior edge of the tendon. CONCLUSIONS: Based on the three-dimensional finite element method, the maximal tensile stress was observed on the articular side of the anterior edge of the supraspinatus tendon. Our result may explain the frequent occurrence of rotator cuff tears at this site.

Scapular inclination and glenohumeral joint stability: a cadaveric study.

BACKGROUND: In shoulders with multidirectional instability, translation of the humeral head on the glenoid is increased in the midrange because of the following three reasons: the increased retroversion, a hypoplastic posteroinferior rim, and decreased scapular abduction during arm elevation. This study aimed to clarify the relationship between glenoid inclination and glenohumeral joint stability. METHODS: Nine fresh-frozen cadaveric shoulders were tested. With a 50-N compressive load, the translation force was measured in the 3-o'clock, 6-o'clock, 9-o'clock, and 12-o'clock directions by using a tilt of 0 degrees , 5 degrees , 10 degrees , 15 degrees , and 20 degrees . When the glenoid was tilted in one direction, the translation force was measured in the direction of inclination and in the opposite direction. The stability ratio was then calculated. RESULTS: The stability ratio in the 3-o'clock direction significantly decreased with a tilt of more than 5 degrees in the 3-o'clock direction. The stability ratio in the 9-o'clock direction significantly decreased with a tilt of more than 15 degrees in the 9-o'clock direction and significantly increased with a tilt of more than 5 degrees in the 3-o'clock direction. The stability ratio in the 6-o'clock direction significantly increased with a tilt of more than 10 degrees in the 6-o'clock direction. CONCLUSIONS: The posterior and inferior stability increased with an anterior tilt of more than 5 degrees and with a superior tilt of 10 degrees , respectively. The anterior and posterior stability decreased with an anterior tilt of 5 degrees and with a posterior tilt of 15 degrees , respectively.