What is the risk of stress risers for interprosthetic fractures of the femur? A biomechanical analysis

Purpose

Due to increasing life expectancy we see a rising number of joint replacements. Along with the proximal prosthesis in the femur, more and more people have a second implant on the distal ipsilateral side. This might be a retrograde nail or a locking plate to treat distal femur fractures or a constrained knee prosthesis in the case of severe arthrosis. All these constructs can lead to fractures between the implants. The goal of this study was to evaluate the risk of stress risers for interprosthetic fractures of the femur.

Methods

Thirty human cadaveric femurs were divided into five groups: (1) femurs with a prosthesis on the proximal side only, (2) hip prosthesis on the proximal end and a distal femur nail, (3) femurs with both a hip prosthesis and a constrained knee prosthesis, (4) femurs with a hip prosthesis on the proximal side and a 4.5-mm distal femur locking plate; the locking plate was 230 mm in length, with ten holes in the shaft, and (5) femurs with a proximal hip prosthesis and a 4.5-mm distal femur locking plate; the locking plate was 342 mm in length, with 16 holes in the shaft.

Results

Femurs with a hip prosthesis and knee prosthesis showed significantly higher required fracture force compared to femurs with a hip prosthesis and a distal retrograde nail. Femurs with a distal locking plate of either length showed a higher required fracture force than those with the retrograde nail.

Conclusions

The highest risk for a fracture in the femur with an existing hip prosthesis comes with a retrograde nail. A distal locking plate for the treatment of supracondylar fractures leads to a higher required fracture force. The implantation of a constrained knee prosthesis that is not loosened on the ipsilateral side does not increase the risk for a fracture.     

Comparison of a sliding hip screw with a trochanteric lateral support plate to an intramedullary hip screw for fixation of unstable intertrochanteric hip fractures: a cadaver study

BACKGROUND: The lateral trochanteric support plate (LSP) was developed to prevent excessive sliding of unstable intertrochanteric femur fractures fixed with a sliding hip screw (SHS). This study compared the fracture stability and screw sliding characteristics of unstable intertrochanteric femur fractures fixed with either an SHS and LSP or an Intramedullary Hip Screw (IMHS). METHODS: Six matched pairs of cadaveric human femurs with simulated, unstable intertrochanteric femur fractures were stabilized with either an IMHS or a 135-degree SHS with an attached LSP. Inferior and lateral head displacements and lag screw sliding distances were measured for applied static loads of 750 N, before and after cycling. RESULTS: Four-part unstable intertrochanteric femur fractures showed comparable screw sliding characteristics and stability whether instrumented with an SHS and LSP or an IMHS. CONCLUSION: A sliding hip screw with an attached lateral support plate provides stability and ability to resist medial displacement of the femoral shaft similar to that seen with the IMHS.     

Locking plates increase the strength of dynamic hip screws

INTRODUCTION: Failure of a dynamic hip screw (DHS) fixation leads to decreased mobility of the patient and frequently to a decrease in general health. The most common mode of failure of a DHS is cut out of the lag screw from the femoral head. The second most common mode of failure is lift-off of the plate from the femur. The aim of this laboratory-based experimental study was to determine whether a DHS secured to an osteoporotic femur with a locking screw plate would provide a stronger construct than the standard DHS plate. METHOD: The standard DHS design was compared to a DHS with fixed angle locking screws holding the DHS plate to the femur. Standard dynamic compression plates (DCP) and locking compression plates (LCP) were attached to synthetic, osteoporotic bone. A load was applied to replicate the forces occurring following the fixation of unstable, intertrochanteric hip fractures. A bracket on the proximal end of the plate replicated the lag screw in the femoral head. The constructs were cyclically loaded by a screw-driven material-testing machine and the number of cycles before failure occurred was determined. RESULTS: The mean number of cycles to failure for the locking plate construct was 2.6 times greater than for the standard screw construct (285 versus 108 cycles, respectively p=0.016). CONCLUSION: A dynamic hip screw with fixed angle locking screws would reduce the risk of DHS failure. A locking screw DHS would be particularly useful in patients with osteoporotic bone, and in patients with less stable fracture configurations.     

Changes and progress in the treatment of fractures of the coxal end of the femur

Consideration of technical developments, a review of the literature and of our own experience with 535 patients compared with nearly 20,000 patients of an ASIF population treated during the same period show that the indications for treatment of extra- and intracapsular fractures of the proximal femur have become much simpler. (1) Extracapsular fractures of the proximal femur fall into two groups: pertrochanteric fractures are fixed by means of the dynamic hip screw and intratrochanteric unstable fractures by means of either the dynamic hip screw (valgus type) or a 95 degrees condylar plate. (2) Intracapsular fractures are treated according to the patient's age group. In patients younger than 70 years femoral head preservation is achieved by compressing screw osteosyntheses, while in patients over 70 years head resection is performed an a total endoprothesis inserted. In patients with life expectation shorter than 3-5 years a femoral head prothesis is inserted.     

保留股骨颈型髋关节假体置换治疗晚期青壮年股骨头坏死中期随访研究

目的 观察保留股骨颈型人工髋关节假体治疗晚期青壮年股骨头坏死的中期疗效.方法 对2002年8月至2009年11月接受置换5年以上的21例28髋青壮年股骨头坏死骨关节炎并接受保留股骨颈型髋关节置换的患者资料进行回顾性分析.患者年龄26～51岁,平均36岁;其中男性16例22髋,女性5例6髋.对随访患者行Harris髋关节评分,拍摄X线片了解假体的位置以及有无松动、远端有无骨质吸收情况.术前Harris评分平均48.5分.结果 2例患者失访,19例26髋获得随访,随访时间63～85个月,平均67个月.3例患者出现下肢不等长,但长度差异＜2 cm.无大腿疼痛发生,无一例患者行髋关节翻修.末次随访时Harris评分平均90.2分.结论 保留股骨颈型髋关节假体置换治疗晚期青壮年股骨头坏死中期疗效满意.     

Differentiated procedure in fractures of the coxal femur end in adults

After own clinical observations a choice of surgical treatment in coxofemoral fractures is pointed out: Femoral neck fractures of stage Garden I will be stabilized by lag screws. For the rest of subcapital fractures we use lag screws or Smith-Peterson nailing for stabilization; only old patients without the possibility of mobilisation without weight-bearing after operation are treated by endoprosthesis of the hip. In Garden-IV-fractures and fracture-type Pauwels III indication for endoprosthesis is conditioned in most elderly patients. In basocervical and pertrochanteric fractures of younger patients a dynamic hip screw will be performed; in older patients we use elastic nails described by Simon-Weidner and Ender with good success. For stabilization of subtrochanteric fractures different operations dependent on type of fracture, bone-structure and general condition are used: elastic nails with or without wire-loops, interlocking nailing, Y-nail, dynamic hip screw, angled plate and compound internal fixation.     

Surgical therapy of medial femoral neck fracture

During 1986 to 1988 64 patients with the diagnosis acute medial hip fracture have been operated in the University Hospital (Charité) by hip endoprosthesis. Patients up to the age of 75 years have been treated by total hip endoprosthesis. Patients older than 75 years got a femoral head prosthesis. In 92.3% of the patients with femoral head prosthesis no complications were observed. In our hospital we prefer the implantation of the femoral head prosthesis in patients older than 75 years.     

Prosthetic care of proximal femur fractures

The endoprosthetic replacement of the hip joint or its components in fractures of the proximal femur is a standard method. Indications for replacement are strongly dislocated intracapsular femoral neck fractures in elderly patients, fractures with an existing arthritis of the hip joint, and profound osteoporosis. Improved perioperative management and more gentle anesthetic techniques have helped to reduce perioperative mortality from nearly 50% to 11.5% over the last 40 years. As routine treatment options, the bipolar endoprosthesis without replacement of the acetabular joint surface and total hip replacement in case of degenerative arthritis of the acetabular joint surface are commonly used. The mere replacement of the femoral head with a simple femoral head prosthesis should be reserved for exceptional cases. For the implantation of a hip joint prosthesis and its uncomplicated post-treatment and long-term durability, careful preoperative planning is essential together with the selection of a suitable implant, its optimal bony fixation, avoidance of intra-operative complications and restoration of the anatomical landmarks such as the centre of rotation of the hip joint, the offset of the prosthetic shaft as well as leg length. Despite the high standard of endoprosthetics in Germany, the results are still improvable in comparison to other countries. Measures which preserve the joint as well as the bone will be increasingly important in prophylaxis of further complications. In addition, more attention should be paid to the prophylaxis of falls and a sufficiently guide-lined therapy of osteoporosis for the prophylaxis of fractures of the elderly.     

The effect of an attachable lateral support plate on the stability of intertrochanteric fracture fixation with a sliding hip screw

BACKGROUND: Use of a sliding hip screw (SHS) alone for some unstable intertrochanteric femur fractures can allow excessive medial shaft displacement during impaction. This study evaluated the effect of an attachable lateral support plate on these fractures after loading. METHODS: Unstable, three-part intertrochanteric fractures were created in 10 matched pairs of embalmed femurs that were instrumented with 135-degree SHSs with or without an attachable lateral support plate. Under physiologic loading, inferior and lateral head displacements and lag screw sliding distances were measured. RESULTS: After 10,000 cycles at 750 N, all measurements for femurs with the lateral support plate were significantly less than for the femurs with the SHS alone: mean lateral difference was 1.7 mm (34%) (p < 0.05), mean inferior difference was 3.0 mm (38%) (p < 0.05), and mean lag screw sliding difference was 4.5 mm (58%) (p < 0.05). CONCLUSION: The addition of an attachable lateral support plate to an SHS significantly decreased displacement of the femoral head after cyclic loading.     

Prothetische Versorgung der proximalen Femurfrakturen

The endoprosthetic replacement of the hip joint or its components in fractures of the proximal femur is a standard method. Indications for replacement are strongly dislocated intracapsular femoral neck fractures in elderly patients, fractures with an existing arthritis of the hip joint, and profound osteoporosis. Improved perioperative management and more gentle anesthetic techniques have helped to reduce perioperative mortality from nearly 50% to 11.5% over the last 40 years. As routine treatment options, the bipolar endoprosthesis without replacement of the acetabular joint surface and total hip replacement in case of degenerative arthritis of the acetabular joint surface are commonly used. The mere replacement of the femoral head with a simple femoral head prosthesis should be reserved for exceptional cases. For the implantation of a hip joint prosthesis and its uncomplicated post-treatment and long-term durability, careful preoperative planning is essential together with the selection of a suitable implant, its optimal bony fixation, avoidance of intra-operative complications and restoration of the anatomical landmarks such as the centre of rotation of the hip joint, the offset of the prosthetic shaft as well as leg length. Despite the high standard of endoprosthetics in Germany, the results are still improvable in comparison to other countries. Measures which preserve the joint as well as the bone will be increasingly important in prophylaxis of further complications. In addition, more attention should be paid to the prophylaxis of falls and a sufficiently guide-lined therapy of osteoporosis for the prophylaxis of fractures of the elderly.     

Spongiosa plug for closing the medullary cavity. A technical variation in the implanting of total hip prosthesis

A modification and the technical details for the implantation of total hip prosthesis is reported. In order to improve stabilisation of the femoral shaft component of the endoprosthesis and to prevent the progress of bone cement also in the distal femoral part of the marrow cavity, the intramedullary cavity is blocked with a bone cylinder prepared from the resected femoral head. Using a special instrument, this bone block is introduced into the intramedullary cavity before filling up the proximal femur with bone cement. Bone cylinders can be prepared and preserved in a bone bank for use whenever necessary.     

Solution for extraarticular hip fractures using the “sliding-screw-nail”-principle. Results of two different systems (classic nail and gamma nail)

Summary Between January 1993 and December 1995 we treated 109 patients (median age: 75 years) with 112 extraarticular hip fractures including combined trochanteric and shaft fractures using two different “sliding-screw-nail implants” (intramedullary hip screw = classic nail: n = 61; gamma nail: n = 51). Comparing the two systems in detail certain advantages and disadvantages were seen, with both being equivalent. We encountered the following complications: secondary varus malalignment of the collum femoris with “cut out” of the sliding-screw (1.8 %) and without “cut out” (1.8 %), fissure of the femoral shaft occuring intraoperatively and being treated conservatively (1.8 %), femoral perforation by the nail (0.9 %), infection (2.7 %). Thus, 5 reoperations (4.5 %) were necessary. None of these complications were attributable to the principle itself or to the different implants used. Each patient was followed-up for a minimum of 12 months postoperatively. In 59 % of all patients the pre-trauma range of mobility could be fully restored. Intramedullary hip screw and gamma nail are excellent and equivalent systems, which fully satisfy the biomechanical needs of above mentioned fractures.      

DHS osteosynthesis for stable pertrochanteric femur fractures with a two-hole side plate

The sliding hip screw is the implant of choice for the operative treatment of stable pertrochanteric femur fractures (AO classification 31-A.1). For this indication, a four-hole side plate with four bicortical screws is widely used to allow full weight bearing immediately after operation, but scientific support for the need of such a long side plate is not available. A shorter side plate is potentially less invasive. Therefore, we retrospectively evaluated all 148 consecutive patients (median age 80 years) with a stable pertrochanteric femur fracture who were treated between 1995 and 2001 with a dynamic hip screw (DHS) and a short (two-hole) side plate and immediate full weight bearing mobilisation. Although two wound hematomas and four wound infections occurred, 145 fractures healed radiologically without implant-related complications within 6 months. Two hip screws cut out of the femoral head due to a poor position. In one patient, the side plate broke out after a fall out of bed on the fifth postoperative day. Pull off of any two-hole side plate during early full weight bearing mobilisation without further trauma was not observed. We conclude that fixation of stable pertrochanteric femur fractures with a two-hole DHS is safe. The traditional use of a four-hole DHS plate for this indication is therefore 'over-treatment' since it is more invasive.     

One-way compression along the femoral shaft with the Medoff sliding plate:The first European experience of 104 intertrochanteric fractures with a 1-year follow-up

This is an assessment of a new device for treatment of intertrochanteric and subtrochanteric fractures. The Medoff sliding plate (MSP) allows compression in 3 different modes: along the femoral shaft, along the femoral neck or a combination of both. In this prospective series of 104 consecutive intertrochanteric fractures, dynamic compression was allowed only along the femoral shaft. Simple undislocated intertrochanteric 2-part fractures were excluded. The patients were followed clinically and radio-graphically for 1 year. 21 patients died within 1 year after the operation. 7 technical failures including 2 non-unions occurred. All were lag screw penetrations, 4 of which were considered to be due to unforced errors by the surgeons.

The technical failure rate in this preliminary evaluation of the MSP is similar to that of the dynamic hip screw. Randomized trials comparing the MSP with other hip screw systems should follow to ascertain possible advantages of the MSP, with its various sliding modes in different types of fractures of the proximal femur.     

采用长解剖型锁定钢板插入技术内固定治疗同侧股骨干骺端及骨干骨折21例

目的探讨采用长干骺端解剖型锁定钢板插入技术内固定治疗同侧股骨干骺端及骨干骨折的特点及疗效。方法自2007—06--2012—06采用长干骺端解剖型锁定钢板内固定治疗21例同侧股骨干骺端及骨干骨折。其中股骨近端合并股骨干骨折14例,股骨远端合并股骨干骨折7例。术中根据骨折部位选择干骺端切口。在股骨干骺端切口放置长干骺端解剖型锁定钢板,固定好干骺端骨折后,再作有限切口复位股骨干骨折。结果本组均获得随访1～3年,平均1．7年。股骨近端合并股骨干骨折骨愈合时间平均（27．21±7．58）周,股骨远端合并股骨干骨折愈合时间平均（24．71±7．64）周,均无钢板、螺钉断裂。1例开放性股骨远端合并股骨干骨折因感染延迟愈合,出现膝关节强直畸形。14例髋关节功能根据Majeed功能评分标准评定：优9例,平均（89．78±2．73）分;良3例,平均（79．00±4．36）分;可2例,平均（63．00±1．41）分。7例膝关节功能按Kolmert标准评定：优4例,良2例,可1例。结论采用较长的解剖型锁定钢板作为内固定材料手术治疗同侧股骨干骺端及骨干骨折是较好的选择。其特点有：①用1种内固定材料固定2个部位骨折,不剥离骨膜,有利于骨折愈合;②锁定螺钉固定后,成为一种角度固定的钢板,集合了钢板内固定和外固定架的优点;③采用有限切口可减少创伤、降低出血量、缩短住院时间。     

Dynamic hip screws that fail

A series of 87 trochanteric fractures of the femur treated by dynamic hip screw, was reviewed. The relationship between the position of the fracture fragments and the position of the hip screw in the femoral head was investigated. Hip screws inserted into some parts of the femoral head were more likely to cut out than others. Some fractures were undisplaced or had been perfectly reduced. A lateral radiograph of some of the others showed that the femoral head and neck were aligned with the shaft. Only among these fractures was the number of good screw placements as great as among those that were undisplaced or perfectly reduced.     

Dall-miles cable-grip system for periprosthetic fractures of femur

Periprosthetic femur fractures are one of the most serious complications in hip surgery. Treatment of femoral shaft fractures complicating endoprosthesis remains controversial.Twenty-one such fractures were treated with Dall-Miles cable grip system. This modified plate allows for fixation using heavy duty circlage cable wire in conjugation with unicortical and bicortical screws throughout the length of the plate. 3 patients with type II transverse periprosthetic fracture with medial communution had primary bone grafting. 20 of the 21 fractures healed in an average of 5.5 months. One patient developed deep infection and died postoperatively. Use of Dall-Miles cable grip system provides immediate rigid fixation allowing early mobilisation.     

PFLCP与PFNA治疗股骨粗隆间骨折的临床疗效比较

目的回顾总结应用股骨近端锁定加压接骨板(proximal femur locking compression plate,PFLCP)与股骨近端螺旋刀片抗旋髓内钉(proximal femoral nail antirotation blade,PFNA)两种手术内固定治疗股骨粗隆间骨折的临床疗效并进行对比分析。方法从2008年7月至2011年10月,收治股骨粗隆间骨折56例,随机分为两组,一组采用PFLCP内固定,另一组采用PFNA内固定。术后分析手术时间、伤口大小、失血量、完全负重时间、骨折愈合时间及内固定位置情况,并通过Harris功能评分评价下肢功能。结果两组顺利完成手术,术后均定期完成随访,平均随访12个月(8～18个月)。PFNA组在切口长度、术后负重时间均优于PFLCP组(P<0.05),两组在手术时间、术中失血量、骨折愈合时间方面比较差异无统计学意义(P>0.05)。PFLCP组出现2例髋内翻、螺钉松动退出、股骨大粗隆滑囊炎,PFNA组2例分别出现颈干角丢失、螺钉切出股骨头和下肢轻度短缩、螺钉稍退出。结论 PFNA和PFLCP两种内固定在股骨粗隆间骨折治疗中均具有较好疗效,PFNA固定允许患者早期负重,两种内固定均具有自己的优势。     

Femoral neck fracture: sliding screw plate versus sliding nail plate--a randomized trial

In a randomized trial 49 patients with fracture of the neck of the femur and an age of less than 70 years or a high level of physical activity were allocated to treatment with a sliding screw plate or a sliding nail plate fixation. The patients were followed for 2-5 years. At follow-up the union rate was found to be 86.2 per cent of the fractures in the screw plate group and 73.7 per cent in the nail plate group (P less than 0.3). Necrosis of the femoral head was encountered in respectively 10 and 21 per cent. Hip replacement was necessary in respectively 23.3 and 31.6 per cent. The nail slid out of the femoral head, resulting in recurrence of the fracture's displacement in three fractures with a sliding nail plate, and in none with a sliding screw plate (P = 0.053). Secondary loss of the femoral neck's angle was more frequently seen in the sliding nail plate group (P less than 0.01). In conclusion, the sliding screw plate gives better fixation of fractures of the neck of the femur and was followed by a lower frequency of reoperation than after an unthreaded device.     

Dynamic internal fixation of the periprosthetic femoral fractures after total hip arthroplasty

Periprosthetic fractures of the femur after total hip arthroplasty are a big orthopaedic problem, particularly in elderly patients and quite a challenge for orthopaedic surgeons. There is no universal method in treating these fractures. Rigid plates fixation can be limited and aggravated especially in the proximal part of the femur where the endoprosthesis stem does not allow for an undisturbed fixation of both femur cortexes by means of screws. Mitkovic's dynamic internal fixator is an original implant allowing for an undisturbed fixation of both femur cortexes regardless of the presence of the endoprosthesis stem. Fixation is made possible by means of movable clamps and a convergent possibility to place screws. A dynamic internal fixator can fix all types of periprosthetic femoral fractures. The paper shows the early experience in fixating periprosthetic femoral fractures after total hip arthroplasty in 14 patients, average age 69.7. According to Vancouver classification, 3 patients had the type A fracture, 9 patients had the type B fracture, and 2 patients had the type C fracture. All fractures were fixed by Mitkovic's dynamic internal fixator. The fracture occurred 2-12 years after primary total hip arthroplasty. The follow-up of the operated patients was 12 months. The method is less invasive than the methods described in books. Mechanical complications are not likely to appear due to the fracture dynamics along the femoral shaft axis, which is made possible by this implant. Our initial experience in femur fracture fixation after hip arthroplasty ahows that it is modern and effective dynamic implant which will contribute significantly to the improving of the treatment of these often very complicated fractures.