Purpose
The purpose of this study was to evaluate whether the presence of an off-track Hill–Sachs lesion has an impact on the recurrence rate after nonoperative management of first-time anterior ...shoulder dislocations.
Methods
A retrospective cohort study was planned with a follow-up via questionnaire after a minimum of 24 months. Fifty four patients were included in the study (mean age: 29.5 years; 16 female, 38 male). All of these patients opted for primary nonoperative management after first-time traumatic anterior shoulder dislocation, in some cases even against the clinician’s advice. The glenoid track and the Hill–Sachs interval were evaluated in the MRI scans. The clinical outcome was evaluated via a shoulder-specific questionnaire, ASES-Score and Constant Score. Further, patients were asked to report on recurrent dislocation (yes/no), time to recurrent dislocation, pain, feeling of instability and satisfaction with nonoperative management.
Results
In 7 (13%) patients, an off-track Hill–Sachs lesion was present, while in 36 (67%) the lesion was on-track and 11 (20%) did not have a structural Hill–Sachs lesion at all. In total, 31 (57%) patients suffered recurrent dislocations. In the off-track group, all shoulders dislocated again (100%), while 21 (58%) in the on-track group and 3 (27%) in the no structural Hill-–Sachs lesion group had a recurrent dislocation,
p
= 0.008. The mean age in the group with a recurrence was 23.7 ± 10.1 years, while those patients without recurrent dislocation were 37.4 ± 13.1 years old,
p
< 0.01. The risk for recurrence in patients under 30 years of age was higher than in those older than 30 years (OR = 12.66,
p
< 0.001).
There were no significant differences between patients with on- and off-track lesions regarding patients’ sex, height, weight and time to reduction and glenoid diameter. Off-track patients were younger than on-track patients (24.9 ± 7.3 years vs. 29.6 ± 13.6 years). However, this difference was not statistically significant.
Conclusion
The presence of an off-track Hill–Sachs lesion leads to significantly higher recurrence rates compared to on-track or no structural Hill–-Sachs lesions in patients with nonoperative management and should be considered when choosing the right treatment option. Therefore, surgical intervention should be considered in patients with off-track Hill–Sachs lesions.
Level of evidence
IV
Background:
The acromioclavicular (AC) capsule is an important stabilizer against horizontal translation and also contributes to the strut function of the clavicle, which guides rotation of the ...scapula. To best reproduce the biomechanical properties and the complex 3-dimensional (3D) guidance of the AC joint, detailed knowledge of the contribution of each of the distinctive capsular structures is needed.
Purpose/Hypothesis:
To perform a detailed biomechanical evaluation of the specific capsular structures of the AC joint and their contribution to translational and rotational stability. The hypothesis was that successive cutting of each quadrant of the AC capsule would result in increased instability and increased amplitude of the clavicle’s motion in relation to the acromion.
Study Design:
Controlled laboratory study.
Methods:
Thirty-two fresh-frozen human cadaveric shoulders were used. Each scapula was fixed to a swivel fixture of a servohydraulic materials testing system. The AC capsule was dissected in serial steps with immediate rotational and horizontal testing after each cut. A 3D optical measuring system was used to evaluate 3D movement. Posterior translation, rotation, and displacement of the lateral clavicle in relation to the center of rotation were measured. Torques and axial forces required to rotate and translate the clavicle were recorded.
Results:
When posterior translational force was applied, all specimens with a completely cut AC capsule demonstrated a significant loss of resistance force against the translational motion when compared with the native state (P < .05). The resistance force against posterior translation was reduced to less than 27% of the native state for all specimens. Sequential cutting of the AC capsule resulted in a significant reduction of resistance torque against anterior rotation for all specimens with less than 22% of resistance force compared with the native state. Cutting 50% of the capsule reduced the resistance torque for all segments and all testing modalities (posterior translation as well as anterior and posterior rotation) significantly compared with the native state (P < .05). Cutting the entire AC capsule resulted in a significant increase in motion within the joint as a sign of decentering of the AC joint when torque was applied. All groups demonstrated a significant increase of motion in all directions when the AC capsule was cut by 50%.
Conclusion:
Cutting the entire capsule (with intact coracoclavicular CC ligaments) reduced the resistance force to less than 25% compared with the native state during translational testing and less than 10% compared with the native state during rotational testing. However, the anterior segments of the capsule provided the greatest stability under rotational loading. Second, the amplitude of the joint’s motion significantly increased under rotational stress, indicating increased amplitude of the clavicle’s motion in relation to the acromion when the ligamentous structures of the AC capsule are dissected.
Clinical Relevance:
To best restore stability to the AC joint, the relevance and function of each section of the circumferential AC capsule need to be understood. Our findings support the synergistic contribution of the CC ligaments and AC capsular structures to AC joint stability. This synergy supports the need to address both structures to achieve anatomic reconstruction.
Purpose
Increased femoral antetorsion influences patellofemoral joint kinematics. The aim of this study was to retrospectively evaluate the clinical outcome after derotational osteotomies and ...combined procedures in patients with patellofemoral instability.
Methods
All patients with derotational osteotomies and combined procedures in patients with patellofemoral instability and increased femoral antetorsion performed between 2007 and 2016 were retrospectively analyzed. Exclusion criteria were open growth plates, posttraumatic deformities, and a follow-up period less than 12 months. Simple radiography and magnetic resonance imaging to evaluate cartilage lesions, trochlear dysplasia, tubercle distance, and osseous malalignment as frontal axis and torsion were performed on every patient. Patients were evaluated pre- and postoperatively using the visual analog scale (VAS) for pain, the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, the subjective IKDC evaluation form, the Lysholm score, and the Tegner activity score.
Results
Out of 222 femoral osteotomies, a total of 42 patients (44 knees) met the inclusion criteria. Mean preoperative femoral antetorsion of 31° (SD ± 9°) and mean valgus malalignment of 1° (SD ± 3°) were observed. An intended derotation of 12° (SD ± 5°) was set overall. The additional procedures included correction of valgus in 50% (
n
= 22), MPFL reconstruction in 64% (
n
= 28), patellofemoral arthroplasty in 18% (
n
= 8), trochleoplasty in 14% (
n
= 6), tibial tubercle transfer in 14% (
n
= 6). During the mean follow-up period of 44 months (SD ± 27, range 12–88), a total of five patients were lost to follow-up, resulting in a follow-up rate of 89% (
n
= 39). A significant pain relief from VAS 4 (SD ± 3) to VAS 2 (SD ± 2) (
p
= 0.006) as well as improved scores, WOMAC: from 80 (SD ± 14) to 88 (SD ± 16) (
p
= 0.007), Lysholm: from 46 (SD ± 21) to 71 (SD ± 24) (
p
< 0.001), IKDC: from 54 (SD ± 13) to 65 (SD ± 17) (
p
< 0.001), were observed postoperatively. During the follow-up period, no patellar re-dislocation was observed.
Conclusion
Combined derotational osteotomy is a suitable treatment for patellar instability due to torsional malformity, as it leads to a significant reduction of pain, and a significant increase of knee function with good-to- excellent results in the short-term follow-up.
Level of evidence
IV.
Purpose
Glenoid retroversion is a known independent risk factor for recurrent posterior instability. The purpose was to investigate progressive angles of glenoid retroversion and their influence on ...humeral head centration and posterior translation with intact, detached, and repaired posterior labrum in a cadaveric human shoulder model.
Methods
A total of 10 fresh-frozen human cadaveric shoulders were investigated for this study. After CT- canning, the glenoids were aligned parallel to the floor, with the capsule intact, and the humerus was fixed in 60° of abduction and neutral rotation. Version of the glenoid was created after wedge resection from posterior and fixed with an external fixator throughout the testing. Specimens underwent three conditions: intact, detached, and repaired posterior labrum, while version of the glenoid was set from + 5° anteversion to − 25° retroversion by 5° increments. Within the biomechanical setup, the glenohumeral joint was axially loaded (22 N) to center the joint. At 0° of glenoid version and intact labrum, the initial position was used as baseline and served as point zero of centerization. After cyclic preloading, posterior translation force (20 N) was then applied by a material testing machine, while start and endpoints of the scapula placed on an
X
–
Y
table were measured.
Results
The decentralization of the humeral head at glenoid version angles of 5°, 10°, 15°, and 20° of retroversion and 5° of anteversion was significantly different (
P
< 0.001). Every increment of 5° of retroversion led to an additional decentralization of the humeral head overall by (average ± SD) 2.0 mm ± 0.3 in the intact and 2.0 mm ± 0.7 in the detached labrum condition. The repaired showed significantly lower posterior translation compared to the intact condition at 10° (
P
= 0.012) and 15° (
P
< 0.01) of retroversion. In addition, CT measured parameters (depth, diameter, and native version) of the glenoid showed no correlation with angle of dislocation of each specimen.
Conclusion
Bony alignment in terms of glenoid retroversion angle plays an important role in joint centration and posterior translation, especially in retroversion angles greater than 10°. Isolated posterior labrum repair has a significant effect on posterior translation in glenoid retroversion angles of 5° and 10°. Bony correction of glenoid version may be considered to address posterior shoulder instability with retroversion > 15°.
Metacarpal shaft fractures are common and can be treated nonoperatively. Shortening, angulation, and rotational deformity are indications for surgical treatment. Various forms of treatment with ...advantages and disadvantages have been documented. The purpose of the study was to determine the stability of fracture fixation with intramedullary headless compression screws in two types of metacarpal shaft fractures and compare them to other common forms of rigid fixation: dorsal plating and lag screw fixation. It was hypothesized that headless compression screws would demonstrate a biomechanical stronger construct.
Five matched paired hands (age 60.9 ± 4.6 years), utilizing non-thumb metacarpals, were used for comparative fixation in two fracture types created by an osteotomy. In transverse diaphyseal fractures, fixation by headless compression screws (n = 7) and plating (n = 8) were compared. In long oblique diaphyseal fractures, headless compression screws (n = 8) were compared with plating (n = 8) and lag screws (n = 7). Testing was performed using an MTS frame producing an apex dorsal, three point bending force. Peak load to failure and stiffness were calculated from the load-displacement curve generated.
For transverse fractures, headless compression screws had a significantly higher stiffness and peak load to failure, means 249.4 N/mm and 584.8 N, than plates, means 129.02 N/mm and 303.9 N (both p < 0.001). For long oblique fractures, stiffness and peak load to failure for headless compression screws were means 209 N/mm and 758.4 N, for plates 258.7 N/mm and 518.5 N, and for lag screws 172.18 N/mm and 234.11 N. There was significance in peak load to failure for headless compression screws vs plates (p = 0.023), headless compression screws vs lag screws (p < 0.001), and plates vs lag screws (p = 0.009). There was no significant difference in stiffness between groups.
Intramedullary fixation of diaphyseal metacarpal fractures with a headless compression screw provides excellent biomechanical stability. Coupled with lower risks for adverse effects, headless compression screws may be a preferable option for those requiring rapid return to sport or work.
Basic Science Study, Biomechanics.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Background:
The synergistic effect of the acromioclavicular (AC) capsule and coracoclavicular (CC) ligaments on AC joint stability has gained recent recognition for its importance. Biomechanical and ...clinical studies have shown the benefit of combined reconstruction with multiple variations of surgical techniques for AC capsule augmentation. The ideal configuration remains unknown for such capsular repair aimed at achieving optimal stability with anatomic reconstruction.
Hypothesis:
Primary AC joint stability can be restored by AC capsule augmentation, while position of the additional suture construct is critical. It was hypothesized that techniques that reconstruct the anterior capsular structures would restore native stability against rotations and translations.
Study Design:
Controlled laboratory study.
Methods:
Thirty fresh-frozen human cadaveric shoulders were used. Each sample was tested in the native state and served as its own control. After complete capsulotomy, 1 of 5 AC capsular repair configurations was performed: anterior, superior, posterior, O-frame, and X-frame. After testing of the AC capsular repair configurations, the tests were repeated after dissection of the CC ligaments and after CC ligament reconstruction with a suture button system. AC joint stability was immediately tested after each step under rotation and horizontal translation. To accomplish this, the AC joints were anatomically positioned on a custom fixture linked to a servohydraulic testing system. A 3-dimensional optical measuring system was used to evaluate the 3-dimensional joint motion. Clavicle posterior translation in relation to the acromion, rotation around the long axis of the clavicle, and displacement of the lateral clavicle in relation to the center of rotation were measured. The torques and forces required to rotate and translate the clavicle were recorded.
Results:
In terms of translational testing, after the complete capsulotomy, a significant reduction of resistance force was found across all groups, with a mean 13% to 20% remaining (P < .05). All AC suture augmentations were able to significantly increase the average resistance force as compared with the native (P = .01) against posterior translation. Subsequent cutting of the CC ligaments did not result in a significant change in any of the groups (P = .23). The synergistic effect of AC capsule augmentation and CC ligament reconstruction could be demonstrated without exception. In terms of rotational testing, the complete capsulotomy resulted in a significant reduction of resistance torque in all groups (P < .05), with a remaining torque ranging between 2% and 11% across the groups. However, all AC suture constructs significantly increased the resistance torque as compared with the capsulotomy (P = .01). The subsequent cutting of the CC ligaments resulted in a significant change in 2 of the 5 groups (O-frame, P = .01; X-frame, P = .02) and an overall remaining torque reduction ranging from 3% and 42%. The combined reconstruction of the AC capsule and CC ligaments achieved the highest percentage of regained resistance torque but remained significantly weaker than the native specimen (P = .01).
Conclusion:
Native translational stability could be restored by the addition of AC capsule augmentation, while partial rotational instability remained. The tested constructs revealed no significant individual differences.
Clinical Relevance:
Combined stabilization of the AC capsule and CC ligaments demonstrated the greatest capacity to restore the native stability against translational and rotational loads, with the specific configuration of the AC capsule repair to be chosen according to the personal preferences of the surgeon.
Purpose
The purpose of the study was to evaluate the frontal gait patterns in patients with chronic patellofemoral instability compared to healthy controls. The hypothesis was that ...internal-rotation–adduction moment of the knee as altered dynamic Q-angle is evident in patients and correlates positively with increased femoral torsion.
Methods
Thirty-five patients with symptomatic recurrent patellofemoral instability requiring surgical treatment were matched for average age, sex, and body mass index with 15 healthy controls (30 knees). Several clinical and radiographic measurements were taken from each participant: internal and external rotation (hipIR, hipER), Q-angle, tubercle sulcus angle (TS-angle), femoral antetorsion (femAT), tibial tubercle–trochlear groove (TT-TG) distance, and frontal leg axis. Additionally, three frontal gait patterns were defined and recorded: (1) internal-rotation–adduction moment of the knee during normal walking, (2) dynamic valgus of the knee, and (3) Trendelenburg’s sign in a single-leg squat. Randomized videography was evaluated by three independent blinded observers. Statistical analysis was performed using regression models and comparisons of gait patterns and clinical and radiological measurements. Furthermore, observer reliability was correlated to gradings of radiological parameters.
Results
Patients showed altered dynamic Q-angle gait pattern during normal walking (
p
< 0.001) compared to healthy controls (interrater kappa = 0.61), whereas highest observer agreement was reported if femAT was greater than 20° (kappa = 0.85). Logistic regression model revealed higher femAT (18.2° ± 12.5 versus 11.9° ± 7.0 (
p
= 0.004) as a significant variable, as well as lower TT–TG distance (23.6 mm ± 2.8 vs. 16.6 mm ± 4.9,
p
= 0.004) on evident dynamic Q-angle gait pattern. Dynamic valgus in a single-leg squat was observed significantly more often in patients (
p
< 0.001) compared to controls (interrater kappa = 0.7). However, besides the static measured Q-angle as the only significant variable on evident dynamic valgus pattern (13.6° ± 4.6 vs. 10.3° ± 5.2,
p
= 0.003), no radiological parameter was detected to correlate significantly with dynamic valgus and Trendelenburg's sign (n.s.).
Conclusions
Clinical detection of pathologic torsion and bony alignment may be difficult in patients with patellofemoral instability. The present study demonstrated that dynamic Q-angle gait pattern is significantly altered in patients with chronic patellofemoral instability compared to healthy controls. Moreover, dynamic Q-angle correlates positively with higher femoral torsion and negatively with higher TT–TG distance. Therefore, clinical and radiological assessment of maltorsion should be added to the standard diagnostic workup in cases of patellofemoral instability.
Level of evidence
Level II.
Background:
Bone marrow aspirate is a primary source for cell-based therapies with increasing value in the world of orthopaedic surgery, especially in revision cases of tendon and ligament repairs. ...However, cells within peritendinous structures, such as the paratenon and surrounding bursa, contribute to the native tendon-healing response and offer promising cell populations for cell-based repair strategies. Therefore, the purpose of this study is to investigate the efficacy of cells derived from human subacromial bursa as compared with the current gold standard, bone marrow stromal cells (BMSCs), for tendon repairs in an established in vivo immunodeficient murine patellar tendon defect model.
Hypothesis:
Subacromial bursal cells will show superior survival and engraftment into the host tissue as compared with BMSCs.
Study Design:
Controlled laboratory study.
Methods:
Human subacromial bursal and bone marrow aspirate were harvested from the same donor undergoing rotator cuff repair. Cells were transfected with a fluorescent lentiviral vector to permanently label the cells, encapsulated into fibrin gel, and implanted into bilateral full-length central-width patellar tendon defects of immunodeficient mice. Additional surgery was performed on control mice comparing fibrin without cells and natural healing. At the time of sacrifice, all limbs were scanned on a multiphoton microscope to monitor the engraftment of the human donor cells. Afterward, limbs were assigned to either immunohistochemical or biomechanical analysis.
Results:
As compared with BMSCs, implanted subacromial bursal cells displayed superior tissue engraftment and survival. The main healing response in this defect model was the creation of new healing tissue over the anterior surface of the defect space. The implantation of cells significantly increased the thickness of the anterior healing tissue as compared with control limbs that did not receive cells. Cell proliferation was also increased in limbs that received implanted cells, suggesting that the donor cells stimulated a more robust healing response. Finally, these changes in the healing response did not lead to significant changes in mechanical properties.
Conclusion:
The subacromial bursa, while often removed during rotator cuff repair, may harbor a more suitable cell source for tendon repair than BMSCs, as bursal cells display superior engraftment and survival in tendon tissue. In addition, the subacromial bursa may be a more accessible cell source than bone marrow aspirate.
Clinical Relevance:
The subacromial bursa contains a cell population that responds to tendon injury and may provide a more optimal cell source for tendon repair and regeneration strategies. Therefore, cells could be harvested from this tissue in the future, as opposed to the current practice of bursectomy and debridement.
Background:
Previous biomechanical studies regarding deltoid function during glenohumeral abduction have primarily used static testing protocols.
Hypotheses:
(1) Deltoid forces required for scapular ...plane abduction increase as simulated rotator cuff tears become larger, and (2) maximal abduction decreases despite increased deltoid forces.
Study Design:
Controlled laboratory study.
Methods:
Twelve fresh-frozen cadaveric shoulders with a mean age of 67 years (range, 64-74 years) were used. The supraspinatus and anterior, middle, and posterior deltoid tendons were attached to individual shoulder simulator actuators. Deltoid forces and maximum abduction were recorded for the following tear patterns: intact, isolated subscapularis (SSC), isolated supraspinatus (SSP), anterosuperior (SSP + SSC), posterosuperior (infraspinatus ISP + SSP), and massive (SSC + SSP + ISP). Optical triads tracked 3-dimensional motion during dynamic testing. Fluoroscopy and computed tomography were used to measure critical shoulder angle, acromial index, and superior humeral head migration with massive tears. Mean values for maximum glenohumeral abduction and deltoid forces were determined. Linear mixed-effects regression examined changes in motion and forces over time. Pearson product-moment correlation coefficients (r) among deltoid forces, critical shoulder angles, and acromial indices were calculated.
Results:
Shoulders with an intact cuff required 193.8 N (95% CI, 125.5 to 262.1) total deltoid force to achieve 79.8° (95% CI, 66.4° to 93.2°) of maximum glenohumeral abduction. Compared with native shoulders, abduction decreased after simulated SSP (–27.2%; 95% CI, –43.3% to –11.1%, P = .04), anterosuperior (–51.5%; 95% CI, –70.2% to –32.8%, P < .01), and massive (–48.4%; 95% CI, –65.2% to –31.5%, P < .01) cuff tears. Increased total deltoid forces were required for simulated anterosuperior (+108.1%; 95% CI, 68.7% to 147.5%, P < .01) and massive (+57.2%; 95% CI, 19.6% to 94.7%, P = .05) cuff tears. Anterior deltoid forces were significantly greater in anterosuperior (P < .01) and massive (P = .03) tears. Middle deltoid forces were greater with anterosuperior tears (P = .03). Posterior deltoid forces were greater with anterosuperior (P = .02) and posterosuperior (P = .04) tears. Anterior deltoid force was negatively correlated (r = −0.89, P = .01) with critical shoulder angle (34.3°; 95% CI, 32.0° to 36.6°). Deltoid forces had no statistical correlation with acromial index (0.55; 95% CI, 0.48 to 0.61). Superior migration was 8.3 mm (95% CI, 5.5 to 11.1 mm) during testing of massive rotator cuff tears.
Conclusion:
Shoulders with rotator cuff tears require considerable compensatory deltoid function to prevent abduction motion loss. Anterosuperior tears resulted in the largest motion loss despite the greatest increase in deltoid force.
Clinical Relevance:
Rotator cuff tears place more strain on the deltoid to prevent abduction motion loss. Fatigue or injury to the deltoid may result in a precipitous decline in abduction, regardless of tear size.
Background:
In the past decade, superior capsular reconstruction has emerged as a potential surgical approach in young patients with irreparable posterosuperior rotator cuff tears (RCT) and absence ...of severe degenerative changes. Recently, the use of locally available and biological viable autografts, such as the long head of the biceps tendon (LHBT) for SCR has emerged, with promising early results.
Purpose/Hypothesis:
The purpose of this study was to investigate the effect of using the LHBT for reconstruction of the superior capsule on shoulder kinematics, along with different fixation constructs in a dynamic biomechanical model. The authors hypothesized that each of the 3 proposed fixation techniques would restore native joint kinematics, including glenohumeral superior translation (ghST), maximum abduction angle (MAA), maximum cumulative deltoid force (cDF), and subacromial peak contact pressure (sCP).
Study Design:
Controlled laboratory study.
Methods:
Eight fresh-frozen cadaveric shoulders (mean age, 53.4 ± 14.2 years) were tested using a dynamic shoulder simulator. Each specimen underwent the following 5 conditions: (1) intact, (2) irreparable posterosuperior rotator cuff tear (psRCT), (3) V-shaped LHBT reconstruction, (4) box-shaped LHBT reconstruction, and (5) single-stranded LHBT reconstruction. MAA, ghST, cDF and sCP were assessed in each tested condition.
Results:
Each of the 3 LHBT techniques for reconstruction of the superior capsule significantly increased MAA while significantly decreasing ghST and cDF compared with the psRCT (P < .001 and P < .001, respectively). Additionally, the V-shaped and box-shaped techniques significantly decreased sCP (P = .009 and P = .016, respectively) compared with the psRCT. The V-shaped technique further showed a significantly increased MAA (P < .001, respectively) and decreased cDF (P = .042 and P = .039, respectively) when compared with the box-shaped and single-stranded techniques, as well as a significantly decreased ghST (P = .027) when compared with the box-shaped technique.
Conclusion:
In a dynamic biomechanical cadaveric model, using the LHBT for reconstruction of the superior capsule improved shoulder function by preventing superior humeral migration, decreasing deltoid forces and sCP. As such, the development of rotator cuff tear arthropathy in patients with irreparable psRCTs could potentially be delayed.
Clinical Relevance:
Using a biologically viable and locally available LHBT autograft is a cost-effective, potentially time-saving, and technically feasible alternative for reconstruction of the superior capsule, which may result in favorable outcomes in irreparable psRCTs. Moreover, each of the 3 techniques restored native shoulder biomechanics, which may help improve shoulder function by preventing superior humeral head migration and the development of rotator cuff tear arthropathy in young patients with irreparable rotator cuff tears.
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