Bone properties of the humeral head and resistance to screw cutout

Surgical treatment of fractures involving the proximal humeral head is hampered by complications. Screw cutout is the major pitfall seen in connection with rigid plating. We have exploited a bony explanation for this phenomenon.

Materials and Methods:

We examined the convex surface of the humeral head looking at the density and the topographical strength of the subchondral bone using mechanical testing of bone cylinders harvested from the humeral head. We also studied the osseous architecture of the subchondral bone and thickness of the boneplate of the humeral head using a 3-dimensional serial sectioning technique.

Results:

The bone strength and bone density correlated well and revealed large regional variations across the humeral head. Bone strength and stiffness of the trabecular bone came to a maximum in the most medial anterior and central parts of the humeral head, where strong textural anisotropy was also found. We found in particular a lower bone strength and density in the posterior and inferior regions of the humeral head. A rapid decline in bone strength within a few mm below a relatively thin subchondral plate was also reported.

Clinical Relevance:

We have in this paper explored some of the most important factors connected with screw stability at the cancellous bone level. We discovered large variations in bone density and bone strength across the joint surface rendering certain areas of the humeral head less suitable for screw placement. The use of rigid plate constructs with divergent screw directions will predictably place screws in areas of the humeral head comprising low density and low strength cancellous bone. New concepts of plates and plating techniques for the surgical treatment of complex fractures of the proximal humerus should take bone distribution, strength, and architecture into account.     

Risk factors for humeral head necrosis and non-union after plating in proximal humeral fractures

AimThe aim of this study was to evaluate risk factors for the development of humeral head necrosis and non-union after proximal humeral fractures—in particular, general risk factors that exist independent of fracture type.Materials and methodsThis study included patients (n = 154) treated for proximal humeral fracture by means of open reduction and internal fixation (ORIF) using the Philos^® plate at a single level I trauma centre between January 2005 and December 2013. Follow-up monitoring included radiographic examination before hospital discharge, and again at 6 weeks, 12 weeks, and 6 months after surgery. At a minimum follow-up time of 6 months, radiographs taken in the anteroposterior and axial projection were evaluated in regard to the development of humeral head necrosis, non-union, and secondary screw cut out.ResultsA total of 154 patients (61 males, 93 females) were available for radiological checkup. Mean age was 55.8 years (range: 19–91 years). There were statistically significant correlations between the development of avascular necrosis (AVN) and fracture type, non-union and smoking, and screw cut out – as well as overall complication rate – and age. The time to surgery did not influence the risk for AVN or non-union, independent of fracture type. In this study population, the risk of developing non-union after ORIF was 3.9-fold higher in heavy smokers (i.e., >20 cigarettes per day). The risk for screw cut out was 4.1-fold higher in patients over 60 years of age, and the overall risk for complications was 3.3-fold higher.ConclusionThe older the patient, the more carefully one must consider the decision between conservative and operative treatments. If surgical treatment is performed, screw length should be selected depending on the patient's age. Heavy smokers must be informed preoperatively of the increased risk for bony non-union after ORIF.     

Surgical treatment of proximal humerus fractures using PHILOS plate

Objective：To evaluate functional outcome and complications of open reduction and internal fixation with proximal humeral internal locking system （PHILOS） plate for proximal humerus fractures.Methods：We reviewed 51 patients who underwent open reduction and internal fixation with PHILOS plate between the years 2007 to 2012.There were 35 men and 16 women with a mean age of 38 years （range 24-68）.There were 41 patients in the age group of ＜60 years and 10 patients in the age group of ＞60 years.According to Neer classification system,8,15 and 23 patients had 2-part,3-part,and 4-part fractures,respectively and 5 patients had 4-part fracture dislocation.All surgeries were carried out at our tertiary care trauma centre.Functional evaluation of the shoulder at final follow-up was done using Constant-Murley score.Results：The mean follow-up period was 30 months （range 12-44 months）.Two patients were lost to followup.Of the remaining 49 patients,all fractures were united clinically and radiologically.The mean time for radiological union was 12 weeks （range 8-20 weeks）.At the final follow-up the mean Constant-Murley score was 79 （range 50-100）.The results were excellent in 25 patients,good in 13 patients,fair in 6 patients and poor in 5 patients.During the follow-up,four cases of varus malunion,one case of subacromial impingement,one case of deep infection,one case of intraarticular screw penetration and one case of failure of fixation were noted.No cases of avascular necrosis,hardware failure,locking screw loosening or nonunion were noted.Conclusion：PHILOS provides stable fixation in proximal humerus fractures.To prevent potential complications like avascular necrosis,meticulous surgical dissection to preserve vascularity of humeral head is necessary.     

Functional outcome following proximal humeral interlocking system plating for displaced proximal humeral fractures

Aim:

To assess the functional outcome following internal fixation with the PHILOS (proximal humeral interlocking system) for displaced proximal humeral fractures.

Patients and Methods:

We reviewed 30 consecutive patients treated surgically with the proximal humeral locking plate for a displaced proximal humeral fracture. Functional outcome was determined using the American Shoulder and Elbow Society (ASES) score and Constant Murley score.

Results:

Average age of the patients was 58 years (range, 19-92 years). The average overall ASES score was 66.5. The average overall Constant score was 57.5.

Conclusion:

Our results show that good fracture stability was achieved, and the functional outcome was very good in younger patients and it declined with increasing age. Early mobilization of the shoulder can be achieved without compromising fracture union.     

人工肱骨头置换治疗肱骨近端骨折18例

目的探讨人工肱骨头置换术治疗肱骨近端骨折的手术疗效。方法对18例肱骨近端骨折行人工肱骨头置换,三部分骨折2例,肱骨头劈裂性骨折1例,四部分骨折11例,四部分骨折伴肩关节脱位4例。全部采用骨水泥型假体。结果手术时间60~90min,平均75min,出血量300~400ml,平均350ml。18例随访6~24个月,平均14个月,疼痛明显解除,按半关节成形改良评分系统SSMH综合评分,优6例,良8例,可4例,优良率78%(14/18)。肩关节活动度平均前屈上举99°(62°~164°),外旋40°(24°~50°),内旋至L2水平。1例大结节上移,1例异位骨化,1例假体松动。结论人工肱骨头置换术是治疗肱骨近端骨折有效的办法,能获得满意的关节活动度,并发症发生率低。     

Influence of plate material and screw design on stiffness and ultimate load of locked plating in osteoporotic proximal humeral fractures

IntroductionThe main purpose was to compare the biomechanical properties of a carbon-fibre reinforced polyetheretherketone (CF-PEEK) composite locking plate with pre-existing data of a titanium-alloy plate when used for fixation of an unstable 2-part fracture of the surgical neck of the humerus. The secondary purpose was to compare the mechanical behaviour of locking bolts and conventional locking cancellous screws.Methods7 pairs of fresh frozen human humeri were allocated to two equal groups. All specimens were fixed with the CF-PEEK plate. Cancellous screws (PEEK/screw) were compared to locking bolts (PEEK/bolt) for humeral head fixation. Stiffness, fracture gap deflection and ultimate load as well as load before screw perforation of the articular surface were assessed. Results were compared between groups and with pre-existing biomechanical data of a titanium-alloy plate.ResultsThe CF-PEEK plate featured significantly lower stiffness compared to the titanium-alloy plate (P < 0.001). In ultimate load testing, 6 out of 14 CF-PEEK plates failed due to irreversible deformation and cracking. No significant difference was observed between results of groups PEEK/screw and PEEK/bolt (P > 0.05).DiscussionThe CF-PEEK plate has more elastic properties and significantly increases movement at the fracture site of an unstable proximal humeral fracture model compared to the commonly used titanium-alloy plate. The screw design however does neither affect the constructs primary mechanical behaviour in the constellation tested nor the load before screw perforation.     

肱骨近端骨折手术与非手术治疗方法疗效分析

目的分析肱骨近端骨折手术及非手术治疗方法的疗效。方法2002～2003年对43例肱骨近端骨折分别采用切开复位解剖钢板、拉力螺钉、克氏针固定及手法复位夹板固定治疗。采用Constant-murley评分方法评定疗效。结果所有患者随访10～19个月,平均11.5个月。24例手术患者中优11例,良8例,可4例,差1例,优良率为79.2%;19例非手术患者中优6例,良7例,可6例,优良率为68.4%;手术疗效明显优于非手术疗效,差异有显著性意义(P<0.05)。X线片示无骨折不愈合及肱骨头坏死发生。结论对Neer分型中Ⅰ型和Ⅱ型中部分患者应采用非手术手法复位夹板固定治疗。而Ⅲ、Ⅳ型应采用手术方法治疗,主要采用解剖钢板固定。拉力螺钉、克氏针作为一种辅助手段,在手术中不宜过多使用。     

应用肱骨近端锁定钢板治疗肱骨近端骨折

目的观察、评价肱骨近端锁定钢板（LPHP）治疗肱骨近端骨折的疗效。方法通过分析自2008—01—2012—10收治并随访的52例肱骨近端二部分以上骨折。采用有限切开、透视复位、肱骨近端锁定钢板内固定的方法治疗,骨缺损患者采用自体髂骨及人工骨植骨。结果本组获得随访8—25个月（平均15个月）,肱骨近端骨折均得到了愈合,按Neer肩关节功能评分标准：优25例,良18例,可6例,差3例,优良率82．7％。未发生断板、断钉,无肱骨头缺血坏死及肩峰撞击综合征。结论应用肱骨近端锁定钢板治疗肱骨近端骨折,骨缺损者取髂骨、人工骨植骨,根据骨折类型及稳定性等指导功能锻炼,骨折愈合良好、并发症少、关节功能恢复好。     

Biomechanical in vitro assessment of screw augmentation in locked plating of proximal humerus fractures

Introduction

Proximal humerus fracture fixation can be difficult because of osteoporosis making it difficult to achieve stable implant anchorage in the weak bone stock even when using locking plates. This may cause implant failure requiring revision surgery. Cement augmentation has, in principle, been shown to improve stability. The aim of this study was to investigate whether augmentation of particular screws of a locking plate aimed at a region of low bone quality is effective in improving stability in a proximal humerus fracture model.

Materials and methods

Twelve paired human humerus specimens were included. Quantitative computed tomography was performed to determine bone mineral density (BMD). Local bone quality in the direction of the six proximal screws of a standard locking plate (PHILOS, Synthes) was assessed using mechanical means (DensiProbe™). A three-part fracture model with a metaphyseal defect was simulated and fixed with the plate. Within each pair of humeri the two screws aimed at the region of the lowest bone quality according to the DensiProbe™ were augmented in a randomised manner. For augmentation, 0.5 ml of bone cement was injected in a screw with multiple outlets at its tip under fluoroscopic control. A cyclic varus-bending test with increasing upper load magnitude was performed until failure of the screw–bone fixation.

Results

The augmented group withstood significantly more load cycles. The correlation of BMD with load cycles until failure and BMD with paired difference in load cycles to failure showed that augmentation could compensate for a low BMD.

Discussion and conclusion

The results demonstrate that augmentation of screws in locked plating in a proximal humerus fracture model is effective in improving primary stability in a cyclic varus-bending test. The augmentation of two particular screws aimed at a region of low bone quality within the humeral head was almost as effective as four screws with twice the amount of bone cement. Screw augmentation combined with a knowledge of the local bone quality could be more effective in enhancing the primary stability of a proximal humerus locking plate because the effect of augmentation can be exploited more effectively limiting it to the degree required.     

锁定接骨板治疗老年肱骨近端骨折

目的探讨肱骨近端锁定接骨板内固定治疗老年肱骨近端骨折的疗效。方法2002年1月～2004年1月对35例老年肱骨近端骨折予以锁定接骨板内固定治疗,术后早期功能锻炼。结果术后所有患者平均随访13.2个月,骨折愈合时间平均8.3周(7～12周),1例肱骨头缺血性坏死。按Constant评分标准,平均81.4分(39～95分),其中优22例,良8例,中4例,差1例,优良率85.7%。结论肱骨近端锁定接骨板对于骨质疏松的老年肱骨近端骨折是一种安全有效的治疗方法。     

Internal fixation of proximal humeral fractures with a Polarus humeral nail

Background  Proximal humeral fractures occur frequently. Displaced or unstable fractures require open reduction and internal fixation. Our objective was to investigate the clinical and radiographic results of the internal fixation using Polarus humeral nails for fractures of the proximal humerus. Materials and methods  From January 2001 to April 2006, 54 shoulders of 54 patients (44 females, 10 males) underwent the intramedullary fixation using Polarus humeral nail. Mean age of the patients was 66-year-old (39–89) at the time of the surgery. Fracture-type by Neer classification was 2-part (29 shoulders), 3-part (22 shoulders) and 4-part (3 shoulders). The clinical and radiological outcomes were evaluated. Results  All the shoulders after osteosynthesis obtained bone-union. There was no osteonecrosis of the humeral head. Functional outcome measured by JOA score averaged 81 points. Totally 43 patients (79%) had satisfactory to excellent results. Varus deformity was seen in 4 shoulders (8%) and the deformity of the greater tuberosity in 4 (8%). Conclusion  The Polarus intramedullary humeral nail is effective for the treatment of proximal humeral fractures.     

肱骨近端锁定钢板治疗肱骨近端粉碎性骨折

目的评价肱骨近端锁定钢板（LPHP）治疗肱骨粉碎性骨折的治疗效果。方法2004年6月～2007年12月应用肱骨近端锁定钢板治疗肱骨近端骨折32例,男14例、女18例,年龄23～85岁,平均57．1±5．8岁。根据Neer分型：二部分骨折6例,三部分骨折21例,四部分骨折5例。术后利用Constant评分评价其治疗效果。结果随诊10个月～3．5年,平均2．1±0．8年,4例失访,随访期末均顺利愈合。1例出现肱骨头部分坏死,但不影响功能;3例出现肩关节半脱位;2例保守治疗缓解;1例出现肩关节撞击征。根据Constant评分为优良率89．2％（25／28）。结论肱骨近端锁定钢板（LPHP）是治疗肱骨近端粉碎性骨折的首选方法之一．可取得较好的临床治疗结果。     

人工肱骨头置换术治疗复杂性肱骨近端骨折

[目的]探讨人工肱骨头置换术治疗肱骨近端复杂性骨折的临床疗效.[方法]35例肱骨近端复杂性骨折患者施行人工肱骨头置换术,手术全部采用骨水泥型人工肱骨头假体.手术前后均对患者的肩关节功能进行UCLA评分.[结果]35例患者随访31～63个月(平均52个月),UCLA评分优(34～35分)10例,良(28～33分)21例,中(21～27分)4例,无差病例.术后肩关节活动范围上举(90.6±8.3)°,外旋(64.5±6.5)°,内旋(72.5±5.3)°.病人主观均较满意.所有病例大小结节均愈合,未发现假体松动、感染、脱位等并发症.[结论]严格掌握手术适应证,重建肱骨近端正常解剖和实现大、小结节骨折块的坚强固定,规范的肩关节功能康复锻炼,是人工肱骨头置换术获得满意疗效的关键.     

肱骨近端骨折术中内侧柱支撑与其术后放射学参数变化及功能相关性

目的观察肱骨近端骨折解剖锁定钢板内固定术中有无内侧柱支撑与其术后放射学参数变化及肩关节功能之间的关系。方法回顾性分析自2012-01—2014-12获得完整随访的59例肱骨近端骨折,所有患者均采用肱骨近端解剖锁定钢板内固定,根据术中肱骨近端有无内侧柱支撑分为内侧柱支撑组(31例)及非内侧柱支撑组(28例)。观察2组术后肱骨头高度丢失、内翻角度及Constant肩关节功能评分。结果 59例术后均获得随访,随访时间平均12.5(6~24)个月。末次随访时,内侧柱支撑组肱骨头高度丢失0.149~4.761(1.527±1.042)mm,内翻角度0.046°~6.772°(2.150±1.802)°,Constant肩关节功能评分(78.129±7.527)分。非内侧柱支撑组肱骨头高度丢失0.343~5.317(2.501±1.290)mm,内翻角度1.429°~22.978°(10.870±4.217)°,Constant肩关节功能评分(65.250±7.801)分。非内侧柱支撑组肱骨头高度丢失(t=3.206,P=0.002)及内翻角度(t=9.962,P0.001)明显高于内侧柱支撑组,内侧柱支撑组Constant肩关节功能评分明显高于非内侧柱支撑组(t=6.451,P0.001)。结论肱骨近端骨折解剖锁定钢板内固定术中内侧柱支撑对于维持术后肱骨头高度及颈干角、改善肩关节功能具有重要的意义。     

手术治疗移位肱骨近端骨折

2000年3月～2005年1月,我科采用手术治疗移位肱骨近端骨折51例,临床疗效满意。     

Humeral head necrosis rate at mid-term follow-up after open reduction and angular stable plate fixation for proximal humeral fractures

Introduction

Short-term follow-up of angular stable fixation for proximal humeral fractures has been well documented in the literature. Longer follow-up series are difficult to find. However, especially regarding the risk of avascular humeral head necrosis longer follow-up series are high of clinical relevance.

Methods

Forty-eight patients with a mean age of 66 years and treated with open reduction and angular stable internal fixation for proximal humeral fractures were followed up for a mean of 45 months. The clinical and radiographic follow-up (Constant Score (CS), age and gender related Constant Score (agCS), Constant Score in comparison to the contralateral side (%CS) and shoulder anterior-posterior and lateral view and axial view X-rays) was performed postoperatively.

Results

Clinical results after 45 months showed a mean CS of 66.2 ± 15.4 points with a mean agCS of 90.0 ± 23.1%. Evaluation of the %CS showed 77.7 ± 17.8%. %CS results showed no significant differences after 45 months in comparison to those obtained after 12 months. However, incidence of avascular necrosis of the humeral head doubled over the follow-up period from 4 cases at 12 months follow-up to 9 cases at final follow-up.

Conclusion

Results of open reduction and internal fixation with angular stable implants for proximal humeral fractures are reliable, however long-term complications such as avascular necrosis of the humeral head need to be evaluated further on since its incidence increases over the time.     

应用肱骨近端锁定型钢板治疗肱骨近端骨折的回顾性研究

目的 探讨AO Philos钢板治疗肱骨近端骨折手术体会.方法 回顾性分析2006年7月-2009年5月应用AO Philos钢板治疗肱骨近端骨折29例,按Neer分型2部分骨折11例,3部分骨折16例,4部分骨折2例.结果 29例患者均获得随访,时间9～16个月,平均11.3个月,功能评定采用肩关节Neer功能评分标准:优13例,良12例,可4例,优良率86.2%.结论 AO Philos钢板治疗肱骨近端骨折具有手术创伤小,固定有效可靠,允许早期功能锻炼,疗效确切.