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Background@#Technical aspects of the correct placement of medial support locking screws in the locking plate for proximal humerus fractures remain incompletely understood. This study was to evaluate the clinical relationship between the number of medial support screws and the maintenance of fracture reduction after locked plating of proximal humerus fractures.@*Methods@#We retrospectively evaluated 181 patients who had been surgically treated for proximal humeral fractures (PHFs) with a locking plate between September 2007 and June 2013. All cases were then subdivided into one of four groups as follows: 75 patients in the medial cortical support (MCS) group, 26 patients in the medial multiscrew support (MMSS) group, 29 patients in the medial single screw support (MSSS) group, and 51 patients in the no medial support (NMS) group. Clinical and radiographic evaluations included the Constant-Murley score (CM), visual analogue scale (VAS), complications, and revision surgeries. The neck-shaft angle (NSA) was measured in a true anteroposterior radiograph immediately postoperation and at final follow-up. One-way analysis of variance or Kruskal-Wallis test was used for statistical analysis of measurement data, and Chi-square test or Fisher's exact test was used for categorical data.@*Results@#The mean postoperative NSAs were 133.46° ± 6.01°, 132.39° ± 7.77°, 135.17° ± 10.15°, and 132.41° ± 7.16° in the MCS, MMSS, MSSS, and NMS groups, respectively, and no significant differences were found (F = 1.02, P = 0.387). In the final follow-up, the NSAs were 132.79° ± 6.02°, 130.19° ± 9.25°, 131.28° ± 12.85°, and 127.35° ± 8.50° in the MCS, MMSS, MSSS, and NMS groups, respectively (F = 4.40, P = 0.008). There were marked differences in the NSA at the final follow-up between the MCS and NMS groups (P = 0.004). The median (interquartile range [IQR]) NSA losses were 0.0° (0.0-1.0)°, 1.3° (0.0-3.1)°, 1.5° (1.0-5.2)°, and 4.0° (1.2-7.1)° in the MCS, MMSS, MSSS, and NMS groups, respectively (H = 60.66, P < 0.001). There were marked differences in NSA loss between the MCS and the other three groups (MCS vs. MMSS, Z = 3.16, P = 0.002; MCS vs. MSSS, Z = 4.78, P < 0.001; and MCS vs. NMS, Z = 7.34, P < 0.001). There was also significantly less NSA loss observed in the MMSS group compared to the NMS group (Z = -3.16, P = 0.002). However, there were no significant differences between the MMSS and MSSS groups (Z = -1.65, P = 0.225) or the MSSS and NMS groups (Z = -1.21, P = 0.099). The average CM scores were 81.35 ± 9.79, 78.04 ± 8.97, 72.76 ± 10.98, and 67.33 ± 12.31 points in the MCS, MMSS, MSSS, and NMS groups, respectively (F = 18.68, P < 0.001). The rates of excellent and good CM scores were 86.67%, 80.77%, 65.52%, and 43.14% in the MCS, MMSS, MSSS, and NMS groups, respectively (χ = 29.25, P < 0.001). The median (IQR) VAS scores were 1 (0-2), 1 (0-2), 2 (1-3), and 3 (1-5) points in the MCS, MMSS, MSSS, and NMS groups, respectively (H = 27.80, P < 0.001). Functional recovery was markedly better and VAS values were lower in the MCS and MMSS groups (for CM scores: MCS vs. MSSS, P < 0.001; MCS vs. NMS, P < 0.001; MMSS vs. MSSS, P = 0.031; and MMSS vs. NMS, P < 0.001 and for VAS values: MCS vs. MSSS, Z = 3.31, P = 0.001; MCS vs. NMS, Z = 4.64, P < 0.001; MMSS vs. MSSS, Z = -2.09, P = 0.037; and MMSS vs. NMS, Z = -3.16, P = 0.003).@*Conclusions@#Medial support screws might help enhance mechanical stability and maintain fracture reduction when used to treat PHFs with medial metaphyseal comminution or malreduction.
Subject(s)
Aged , Female , Humans , Male , Middle Aged , Bone Plates , Bone Screws , Fracture Fixation, Internal , Methods , Humerus , Retrospective Studies , Shoulder Fractures , General Surgery , Treatment OutcomeABSTRACT
Objective To design a novel double-leaf proximal humeral locking plate for fixing greater and lesser tuberosities in complex proximal humeral fractures, and evaluate its fixing stability by biomechanical tests. Methods Twelve fresh-frozen humerus specimens with intact rotator cuff were randomly divided into two groups (Group A and Group B) to establish the same greater and lesser tuberosities fracture models. Specimens in Group A were fixed with the double-leaf proximal humeral locking plate, while specimens in Group B were fixed with the proximal humeral internal locking system (PHILOS) and tension band suture, and a 3.5-mm cannulated screw was added to stabilize the lesser tuberosity. The tensile test on subscapularis, infraspinatus and teres, supraspinatus as well as the load-to-failure test on greater and lesser tuberosities were performed on specimens in two groups. Results For subscapularis tensile tests, displacements under 150 N tensile stretch and after fatigue test in Group A were both significantly smaller than those in Group B (P0.05). For supraspinatus tensile tests, there were no statistical differences between Group A and B in displacements under 90 N tensile stretch and after fatigue test (P>0.05). For load-to-failure tests on lesser tuberosity, the failure load in Group A was significantly greater than that in Group B (P0.05). Conclusions Compared with the ordinary tension band suture plus cannulated screw for fixing lesser tuberosity, the novel double-leaf proximal humeral locking plate shows more obvious biomechanical stability, with the advantage of simultaneously fixing greater and lesser tuberosities. The research findings provide a new choice for the clinical treatment of complex proximal humeral fractures.
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Objective To design a novel double-leaf proximal humeral locking plate for fixing greater and lesser tuberosities in complex proximal humeral fractures,and evaluate its fixing stability by biomechanical tests.Methods Twelve fresh-frozen humerus specimens with intact rotator cuff were randomly divided into two groups (Group A and Group B) to establish the same greater and lesser tuberosities fracture models.Specimens in Group A were fixed with the double-leaf proximal humeral locking plate,while specimens in Group B were fixed with the proximal humeral internal locking system (PHILOS) and tension band suture,and a 3.5-mm cannulated screw was added to stabilize the lesser tuberosity.The tensile test on subscapularis,infraspinatus and teres,supraspi natus as well as the load-to-failure test on greater and lesser tuberosities were performed on specimens in two groups.Results For subscapularis tensile tests,displacements under 150 N tensile stretch and after fatigue test in Group A were both significantly smaller than those in Group B (P ＜ 0.05).For infraspinatus and teres tensile tests,there were no statistical differences between Group A and B in displacements under 150 N tensile stretch and after fatigue test (P ＞ 0.05).For supraspinatus tensile tests,there were no statistical differences between Group A and B in displacements under 90 N tensile stretch and after fatigue test (P ＞ 0.05).For load-to-failure tests on lesser tuberosity,the failure load in Group A was significantly greater than that in Group B (P ＜ 0.05),and the failure displacement in Group A was significantly smaller than that in Group B (P ＜ 0.05).For load-to-failure tests on greater tuberosity,there were no statistical differences between Group A and B in both the failure load and failure displacement (P ＞ 0.05).Conclusions Compared with the ordinary tension band suture plus cannulated screw for fixing lesser tuberosity,the novel double-leaf proximal humeral locking plate shows more obvious biomechanical stability,with the advantage of simultaneously fixing greater and lesser tuberosities.The research findings provide a new choice for the clinical treatment of complex proximal humeral fractures.
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Objective To evaluate the biomechanical advantages of medial support screws (MSSs) in locking proximal humeral plate for treating proximal humerus fractures. Methods Thirty synthetic left humeri were randomly divided into 3 groups to establish the fracture models. Group A was fixed with a locking proximal humerus plate with medial cortical support, but without MSSs; group B was fixed with 3 MSSs, but without medial cortical support; group C was fixed with neither medial cortical support nor MSSs. Axial compression, torsion, shear stiffness and failure tests were applied on the specimens of the three groups. Results For axial compression tests, the maximum load of group A, B, C was (240.88±19.13), (169.04±19.26), (128.58±17.53) N, respectively; the axial stiffness of group A, B, C was (424.4±101.2), (230.7±40.54), (147.0±29.2) N/mm, respectively, showing significant differences (P0.05). For shear stiffness tests, the maximum load of group A, B, C was (444.71±20.87), (228.79±28.95), (188.73±26.15) N, respectively; the shear stiffness of group A, B, C was (70.0± 54.4), (183.89±29.64), (140.2±32.1) N/mm, respectively, showing significant differences (P0.05). Conclusions Using three MSSs in locking plate for proximal humerus fractures shows optimal biomechanical properties, as compared to the situation without restoration of the medial column support. The reconstruction of the medial cortical support or MSSs for proximal humerus fractures helps to enhance the mechanical stability of the humeral head and prevent failure after internal fixation.
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Objective To analyze the stress distribution and peak stress on midshaft clavicular fractures fixed by titanium elastic nail (TEN) or reconstruction plate, respectively. Methods CT data of the clavicle was adopted to reconstruct the intact clavicle model and the midshaft clavicular fracture models with the TEN and reconstruction plate fixation by using Mimics software. All the three dimensional finite element models were analyzed using Abaqus 6.9 software. The distal displacement, the peak stress and stress distribution on the distal clavicle under the axial load (250 N) and vertical load (250 N) were calculated for the three models. Results The axial displacement of the distal clavicle under the axial load showed TEN (0.23 mm)>intact clavicle (0.14 mm)>reconstruction plate (0.11 mm), respectively. While the vertical displacement of the distal clavicle under the vertical load was 5.12 mm for TEN, 3.71 mm for intact clavicle and 2.25 mm for reconstruction plate, respectively. But the peak stress of the clavicle under the axial load was 33.1 MPa for TEN, 18.7 MPa for reconstruction plate, and 15.5 MPa for intact clavicle model, respectively. And the peak stress under the vertical load was 146.3, 64.1, 56.1 MPa in the TEN, intact clavicle model, and reconstruction plate model, respectively. The stress distribution in TEN model under both kinds of loads was similar to that in intact clavicle model, while under the vertical load, the stress distribution in reconstruction plate model was clearly different with that in intact clavicle model. For the implants under the axial load, the peak stresses were 191.5, 52.3 MPa in the TEN model and reconstruction plate model, respectively, and the peak stress on implants under the vertical load was 1 248.0, 421.7 MPa in the TEN model and reconstruction plate model, respectively. Conclusions The TEN for treating midshaft clavicular fractures showed a stress distribution similar to the intact clavicle, with a higher peak stress and a higher peak implant stress at the fracture site. The reconstruction plate fixation for midshaft clavicular fractures was shown to be more stable, but with obvious stress shielding. Therefore, TEN is generally preferable for treating the simple displaced fractures of midshaft clavicle. However, the ipsilateral shoulder should avoid excessive exercise and weight bearing in the early postoperative period.
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Objective To compare the stability of greater tuberosity fractures of humerus treated by three different fixation techniques (screws, tension band, locking plate, respectively) through biomechanical testing, so as to provide the biomechanics basis for choosing a better fixation in the clinical treatment for greater tuberosity fractures of humerus. Methods Standardized fracture models of the greater tuberosity from 18 fresh-frozen proximal humeri with intact rotator cuffs were created. The specimens were randomly assigned to 3 groups and treated by screws, tension band and locking plates, respectively. An increasing force was applied to the supraspinatus tendon. The force displacement curve and two parameters: LtYP(Load to 5 mm yield point) and Ltf(load to failure) were recorded. Results LtYP from the screw group, tension band group and locking plate group was (377±86), (499±90), (793±52) N, respectively, with significant differences among the three groups (P0.05). Conclusions Locking plates show more obvious biomechanical stability than screws and tension band, which provides a new and better choice for treatment of isolated greater tuberosity fractures of humerus.
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Objective To compare the biomechanical behavior of a triple Endobutton technique for anatomic reconstruction of coracoclavicular ligament and with a modified Weaver-Dunn procedure. Methods Twelve fresh frozen cadaveric shoulders were applied with 70 N in superior, anterior and posterior direction, respectively, to measure displacement of the acromioclavicular joint. The failure test with the load at the rate of 25 mm/min was conducted to record the failure load and failure mode. The specimens were then randomly assigned to 2 groups: the triple Endobutton technique group and the modified Weaver-Dunn procedure group for reconstruction and to conduct displacement test and failure test again. The stability and mechanical strength of acromioclavicular joints after reconstruction under different states were then compared. Results The triple Endobutton technique group had significantly less anterior ((8.72±1.41) mm vs (37.03±5.05) mm) and posterior ((8.03±3.68) mm vs (14.85±1.89) mm) displacement than that in the modified Weaver-Dunn procedure group after reconstruction (P<0.05), and the former had similar displacement ((7.81±2.22) mm anterior and (7.16±1.95) mm posterior) as compared to the intact state. There were no significant differences in superior displacement among the groups. The modified Weaver-Dunn procedure group had significantly smaller failure loads ((172±9) N) than that in the triple Endobutton technique group ((687±115) N) and the intact ligament group ((685±234) N) (P<0.05). Conclusions The triple Endobutton technique has less anterior and posterior displacement and its stability is more closely approximate to the intact ligament; meanwhile, it has similar strength as coracoclavicular ligaments, which can better restore the function of coracoclavicular ligaments.