Abstract

BACKGROUND: Bone and exact reduction and internal fixation should be kept to fully repair the function of patella in comminuted patellar fracture operation. Currently, comminuted patellar fracture without a unified therapeutic standard has been a difficulty in clinic.

OBJECTIVE: To compare the effects of modified AO tension band, titanium cable cerclage and nickel-titanium (Ni-Ti) patellar concentrator fixation in the treatment of comminuted patellar fracture.

DESIGN: Prospective comparative observation.

PARTICIPANTS: Totally 60 patients with simple unilateral closed comminuted patellar fracture were enrolled at Department of Orthopaedics of Changzheng Hospital from November 2004 to November 2006, including 32 males and 28 females aged 28-59 years. Inclusive criteria contained diagnosis of having simple unilateral closed comminuted patellar fracture and injury timing of less than 7 days. The patients all signed the informed consent.

METHODS: The patients were assigned into modified AO tension band group (n =22), titanium cable cerclage group (n = 21) and Ni-Ti patellar concentrator group (n =17) according to their will. Twelve patients in the modified AO tension band group received simple modified AO tension band internal fixation, and ten received modified AO tension band internal fixation and extraction. Patients in the titanium cable cerclage group received titanium cable cerclage. Ten patients in the Ni-Ti patellar concentrator group received simple Ni-Ti patellar concentrator internal fixation, and seven received internal fixation and extraction.

MAIN OUTCOME MEASURES: ①Postoperative host and material reaction, intraoperative blood loss, medical cost and workday loss, and ②active range of knee motion at month 3 after operation and functional recovery and curative effect at month 6 after operation.

RESULTS: Totally 60 patients were involved in the result analysis. ①Host and material reaction was not found in all patients. Blood loss was significantly more in the patients of simple Ni-Ti patellar concentrator internal fixation group than patients of simple modified AO tension band internal fixation group and titanium cable cerclage group, whereas workday loss was less than that of the simple modified AO tension band internal fixation group (P < 0.05). Medical cost was obviously more in the titanium cable cerclage group than the simple Ni-Ti patellar concentrator internal fixation group and the simple modified AO tension band internal fixation group (P < 0.05). ②Active range of knee motion was the largest, about mean 108°, and long-term functional score of injured knee was the highest, about mean 21.3 points, with the excellent and good rate of 95.2%, and no sever complication appeared in the titanium cable cerclage group. These were much better than those of the other groups (P < 0.05).

CONCLUSION: Modified AO tension band fixation and patellar concentrator fixation in the treatment of comminuted patellar fracture have excellent effects in some patients. Titanium cable cerclage fits for the treatment of comminuted patellar fracture and has better recovery of knee joint function.

INTRODUCTION

Totally or partial patellar excision would result in complete uneven contact patellofemoral joint [1]. Bone and exact reduction and internal fixation should be kept to fully repair the function of patella in comminuted patellar fracture operation [2]. Totally or partial patellar excision as a redeem measure could be utilized when fracture could not be reset [3-5]. Modified AO tension band for simple comminuted fracture had good effects [6]. Nickel-titanium (Ni-Ti) patellar concentrator fixation for comminuted patellar fracture had good effects [7, 8]. Thick silk/steel-wire cerclage fixation was fitted for various patellar fracture on the theory, but the effect was not clear, with many complications, short-term and long-term functional recovery was poor [9]. In this study titanium cable cerclage was used for treating comminuted patellar fracture, and the curative effect was compared with using modified AO tension band and patellar concentrator.

SUBJECTS AND METHODS

Subjects
A total of 60 patients with simple unilateral closed comminuted patellar fracture were enrolled at Department of Orthopaedics of Changzheng Hospital from November 2004 to November 2006, containing 32 males and 28 females aged 28-59 years. Inclusive criteria contained diagnosis of having simple unilateral closed comminuted patellar fracture and injury timing of less than 7 days. Exclusive criteria included ①patients with multiple wound, combined injury, preoperative diabetes, autoimmune disease (AID), metabolic bone disease (MBD), significant osteoporosis, and ②patients with degeneration, osteoarthritis and dynamic instability of knee joint who had bad compliance and could not finish follow-up. The patients knew the experimental aim and operational methods. The patients were assigned into modified AO tension band group (n =22), titanium cable cerclage group (n =21) and Ni-Ti patellar concentrator group (n =17) according to their will. Twelve patients in the modified AO tension band group received simple modified AO tension band internal fixation, and ten received modified AO tension band internal fixation and extraction. Patients in the titanium cable cerclage group received titanium cable cerclage. Ten patients in the Ni-Ti patellar concentrator group received simple Ni-Ti patellar concentrator internal fixation,
and seven received internal fixation and extraction.

Methods
Therapeutic process:Anterior median knee joint was incised under subarachnoid anesthesia. Under straight sight we made the fracture diaplasis after the management of bone surface. After diagnosing articular surface was even with C arm equipment, fracture blocks were fixed temporarily with towel forceps by different methods.
Modified AO tension band group: Patients bent their knees at 10°-20°. Two horizontal Kirschner wires of 2 mm diameter were penetrated from inferior margin of patella to superior margin longitudinally, traversed through quadriceps femoris of patellar superior margin, and then the No. 20 steel-wire was tensed and tied by four needle end in the form of "8". Patients bent their knees at 90° when articular surface was even. Separation was not found among fracture blocks. Unnecessary Kirschner wire was sheared at 0.5 cm from patella, and the caudal end of Kirschner wire was bent backwards to tightly close to upper patella. Broken quadriceps femoris's tendon or patellar ligament was sutured in the form of "8". Titanium cable cerclage group: One titanium cable was selected, and sheared into two titanium cables along middle point. Cerclage was performed at the anterior 1/3 and posterior 1/3 sagittal plane of patella. Titanium cable was tensed with ratchet tie down strap at "30" pound and fixed with temporal fixator. When the joint surface was even, the patients bent their knee at 90° to identify no divergence phenomenon among fracture blocks. Lock catch was tensed with caging clamp, and then titanium cable was cut with cable scissor along lock catch. Broken quadriceps femoris's tendon or patellar ligament was sutured in the form of "8". Ni-Ti patellar concentrator group: two and three 0.5 cm incisions were respectively made at superior patella and patellar ligament. Five claws of suitable Ni-Ti patellar concentrator was unfolded in ice salt water, respectively inserted in the five incisions mentioned above, closely to the patella. The patellar concentrator was heated in 40 ℃-50 ℃ salt water, namely memory patellar concentration. When the joint surface was even, the patients bent their knee at 90° to define no divergence phenomenon among fracture blocks. Broken quadriceps femoris's tendon or patellar ligament was sutured in the form of "8". Injured limbs were elevated after operation in the three groups. According to fracture degree and stability of internal fixation, stretch-flexion exercise or long leg splint fixation were performed with Continuous Passive Motion machine.
Postoperative general data: Postoperative host and material reaction, operation timing, intraoperative blood loss, time of postoperative stretch-flexion exercise, hospitalization day, medical cost and workday loss are recorded. Data mentioned above of the two internal fixation and extraction groups were the sum of the two operations. Workday loss refers to from the beginning of simple patellar fracture to return to work for patients having a job, and from the beginning of injury to live by themselves basically for patients having no jobs, who go into early retirement or honorary retirement caused by this injury. Self-care standard was based on the activities of daily living (ADL) without external fixation or orthosis. Barthel ADL Index Scale (0-100 points) was utilized[10], and those with over 60 points as basic self-care.
Range of knee motion: Active range of knee motion was measured at month 3 after operation.
Long-term function: The patients were asked for more information on disease, and bodies were examined 6 months or longer after operation. Symptom and Sign Comprehensive Scoring Criteria was utilized [11], and mean score was obtained. Criteria included joint pain, walking, abilities of upstairs, downstairs and squatting, extension lag degree of knee joint, flexion degree of knee joint, muscle force of quadriceps femoris, thigh circumference at the site 15 cm superior to head of fibula and patellofemoral joint surface. Each item was scored by excellent, good, fair and poor, respectively as 4 points, 3 points, 2 points and 1 point, totally 24 points. Curative effect was assessed by total score, and excellent as 22-24 points, good as 17-21 points, fair as 11-16 points and poor as 5-10 points.
Statistical analysis: These data were analyzed by the first author with SPSS 13.0 software. The t test or variance analysis was used for statistical analysis. Measurement data were expressed as Mean±SD. Enumeration data were expressed by Chi-square. P < 0.05 expressed statistical significance.

RESULTS

Quantitative analysis of participants
Totally 60 patients were involved in the result analysis.

Relevant therapeutic indexes of patients in the three groups (Table 1)

Knee joint range of motion (Table 2)

Excellent and good rate of long-term function (Table 3)

General condition and long-term effect of patients (Table 4)

Postoperative complications and management
In the modified AO tension band group, Kirschner wire or steel-wire pierced the skin in 3 cases; suture part was split in 1 case; stab wound in skin appeared with loose Kirschner wire in 10 cases; bursitis with pain occurred in 8 cases; steel-wire was prolapsed from Kirschner wire in 4 cases; bony spur was found in 1 case, and osteoarthritis was seen in 2 cases. These were debrided and sutured, and genuflex was restricted. Internal fixation was removed after fracture union. Symptomatic treatment was performed.
In the titanium cable cerclage group, titanium wire pierced the skin in 4 cases, and treated with drugs. These symptoms disappeared after chipping the embedding region under local anesthesia. Four weeks after injured knee could move, a strand of titanium cable was broken in 1 case, but no special intervention was conducted, besides, normal knee functional exercise was performed. In the Ni-Ti patellar concentrator group, stab wound in skin appeared with internal fixation in 1 case, and osteoarthritis in 1 case. Activity was restrained. Internal fixation was removed after fracture union. Symptomatic treatment was performed.

Biocompatibility of materials with hosts
Late healing, disunion or side effects resulted from biocompatibility was not found in the three groups.

DISCUSSION

Some patients with excellent long-term function of the modified AO tension band group began to do extension-flexion exercise in 7 days after operation, the earliest at day 2. These cases were characterized by mild fracture, 3 fracture blocks, big block and fitting for fixation with Kirschner wire. In the 3-month recheck, ROM of injured knee was averagely 102°, maximally 115°; long-term score was averagely over 18 points. Most patients received long leg splint or long leg brace for 3 weeks or longer. Fracture was complicated, line of fracture was irregular, block was small and irregular, and the two Kirschner wires could not once stabilize fracture block. These would cause more workday loss, late injured knee exercise and small active range of motion. Fixation with tension band can cause many complications, which are mainly induced by stab wound in skin following knee activity with loose Kirschner wire, including infection, bursitis and steel-wire slippage. Slippage is resulted from: firstly, tension from tension band fixator on patella when flexion of knee joint is done after operation. Secondly, compressive stress on patella from condyles of femur affects steel-wire and Kirschner wire. Thirdly, the end of Kirschner wire scrapes with quadriceps femoris's tendon when doing exercise, resulting in up and down movement of the Kirschner wire, even breakage or slippage of steel-wire. Tension band cannot fix every block, so bony spur is formed by tiny block exfoliation when doing exercise. Thus, patellar fracture blocks are big, and fit for Kirschner wire fixation. Modified AO tension band can be utilized if the patients can accept the secondary operation. The Kirschner wire should be fixed tightly to avoid complications caused by loose.
Ni-Ti patellar concentrator fixation with the shape memory effect had the ability of exerting concentration press to extremities from multiple directions, centripetally, successively, and automatically[12]. However, the moulding time was short, which would result in fixation failure in short time or uneven fracture surface after fixation, and then readjustment or re-fixation was deserved. This was the cause of longer operation timing in the Ni-Ti patellar concentrator group. Patients with excellent long-term function received extension-flexion exercise in a week; so most patients began to do the functional exercise before discharge. Long-term functional score was over 19 points. Fracture was characterized by large block, big lateral wedge fracture block and fitting for patellar concentrator fixation. Patellar concentrator can produce longitudinal stress. For patients with severe comminuted fracture or small lateral wedge fracture block, fixation press is not enough and can lead to displacement or exfoliation fracture, so external fixation is necessary after operation. These cause postoperative small ROM and low long-term functional score. Ni with definite carcinogenesis is the most common contact metallic allergen[13-15], so internal fixation should be removed after fracture healing. Because moulding time was short and bone grew around concentrator. claws after healing, time of removing concentrator was significantly longer and bleeding amount were significantly more than the tension band extraction group Pain induced by stab wound in skin with internal fixator was found in 1 case of the Ni-Ti patellar concentrator group. It was associated with large patellar concentrator and thin body of the patient. Osteoarthritis was seen in 1 case, because of displacement of lateral small wedge fracture and forming over 2 mm echelon on joint surface, beside the destruction of articular cartilage. Patellar concentrator was used when fracture block was large, no small lateral wedge fracture block was seen, the angle was big between fracture line and longitudinal axis, as well as the patient could accept the secondary operation. Soft tissue should cover the patellar concentrator during operation, and internal fixation should be extracted after operation in time.

Titanium cable not only has the advantages of thick silk and steel-wire, but also can overcome the disadvantages, so it can play an important role in the treatment of comminuted patellar fracture. Each titanium cable composed of multiple (7×7) titanium wires is easy to bend. When bending, the titanium cable is very tenacious like cord; when tensing, it will be closely near to bone. Compared with the traditional steel-wire, titanium cable has great tensile strength, high anti-fatigue wear-resistance abilities, and its rigidity is close to cortical bone. No change of titanium cable was found in 24 hours under stress, but steel-wire was intended to straighten after twist, so perceptible elongation was seen in early phase[16]. Titanium cable can develop but does not produce obvious artifacts with which that of other kinds of material are not compared. With special instrument, we can precisely control tensile strength, which will keep a better effect and avoid cutting bone by high tensile strength. Special lock can keep it stable when cable is broken. It with small volume and good histocompatibility and without toxic or adverse effect has a little effect on function and little on MRI recheck. Titanium cable cerclage not only had the traditional characteristics such as drawing fracture block together, simple operation, but also could overcome some disadvantages such as unclear press, small tensile force, no early functional exercise, poor long-term functional recovery[10]. Elastic modulus is equal to human skeleton, cannot result in stress dodge, and with good histocompatibility the secondary operation is not deserved. The force of cerclage can be precisely adjusted, so a unified standard is easy to be established to further exclude the difference from the patients. The findings of this experiment showed that titanium cable cerclage for comminuted patellar fracture can stabilize fracture block and fits for various comminuted fracture, no matter the type, shape or place of fracture. Titanium cable cerclage can lead to early extension-flexion functional exercise (mean 5.7 days), shorten workday loss (mean 43.7 days), and have better long-term functional recovery and higher long-term excellent and good rate. The only shortage is high price. In the titanium cable cerclage group, titanium wire pierced the skin in 4 cases, but these symptoms disappeared after chipping the lock catch and embedding it in lateral patellar soft tissues. A strand of titanium cable was broken in 1 case after extension-flexion exercise, which was caused by great tightening strength. Thus, tightening strength should be read exactly, but not exceed 30 pound. In a word, titanium cable cerclage can be utilized for comminuted patellar fracture to obtain better short-term and long-term functional recovery, especially when other methods cannot effectively fix the bone.

REFERENCES

1 Wang YC. Bone and Joint Injury. 3rd ed. Beijing: People's Medical Publishing House 2001:1024
2 Pritchett JW. Nonoperative treatment of widely displaced patella fractures. Am J Knee Surg 1997;10(3):145-147
3 Veselko M, Smrkolj V, Tonin M. Comminuted avulsion fractures of the inferior pole of the patella. Unfallchirurg 1996;99(1):71-72
4 Cantin S, Laroche C, Lavallee P, et al. Patellectomy: results of a long-term follow-up. JMCan J Surg 1993;36(5):461-463
5 Gunal I, Taymaz A, Kose N, et al. Patellectomy with vastus medialis obliquus advancement for comminuted patellar fractures: a prospective randomised trial. J Bone Joint Surg Br 1997;79(1):13-16
6 Wang YC, Bi WC, Gao JZ, et al, Practical evidence of the therapeutic principal of the patella fracture. Zhonghua Chuangshang Guke Zazhi 1990;6(3):133-136
7 Milankov M, Miljkovic N, Stankovic M. Treatment of the knee stiffness caused by partial patellectomy--technical tricks. Indian J Med Sci 2005; 59(12):534-537
8 Catalano JB, Iannacone WM, Marczyk S, et al. Open fractures of the patella: long-term functional outcome. J Trauma 1995;39(3):439-444
9 Kolndorfer G, Boszotta H, Prunner K, et al. Long-term results of surgical management of patellar fractures. Conservative versus resection procedures. Unfallchirurgie 1994;20(1):37-41
10 Gu M, Yao YH, Gu XD. The affection of early rehabilitative exercise to the Barthel index of the post-operation patients of femoral neck fracture. Zhonghua Wuli Yixue yu Kangfu Zazhi 2002;24 (1):59
11 Xu ST, Ge BF, Xu YK. Practical orthopeadics. 2nd ed. Beijing: People's Military Medical Publishing House 1999:702
12 Zhang CC, Wang JL, Xiao J, et al. Treatment of the patella fractures with Nickel Titanium-Patella Catcher and it's biomechanics characters. Gu yu Guanjie Sunshang Zazhi 1996;11(2):78-80
13 Yu W. Allergy infects people's health. Yiyao Baojian Zazhi 2003;10:18
14 Cavani A. Breaking tolerance to nickel. Toxicology 2005;209(2):119-121
15 Costa M, Davidson TL, Chen H, et al. Nickel carcinogenesis: epigenetics and hypoxia signaling. Mutat Res 2005;592(1-2):79-88
16 Dickman CA，Papadopoulos SM，Crawford NR，et al. Comparative mechanical properties of spinal cable and wire fixation systems. Spine 1997;22(6):596-604

三种不同内固定植入物治疗髌骨粉碎性骨折的效果比较★

李 阳，欧阳跃平，苟三怀，袁 文，刘 岩，孙 巍
解放军第二军医大学长征医院骨科，上海市 200003
李 阳★，男，1980年生，四川省成都市人，汉族，2007年解放军第二军医大学毕业，硕士，医师，主要从事创伤骨科研究。
通讯作者：欧阳跃平，硕士生导师，副主任医师，副教授，解放军第二军医大学长征医院骨科，上海市 200003
摘要
背景：髌骨粉碎性骨折的手术治疗应尽量保留骨质及精确的复位内固定，充分恢复髌骨的功能，目前髌骨粉碎性骨折尚无统一的治疗标准，仍是临床上的难点。
目的：比较AO改良张力带、钛缆环扎及镍钛聚髌器固定法治疗髌骨粉碎性骨折的效果。
设计：前瞻性对比观察。
对象：选择2004-11/2006-11解放军第二军医大学长征医院骨科收治的60例单纯单侧闭合性髌骨粉碎性骨折患者，男32例，女28例，年龄28~59岁。纳入标准：明确诊断为单纯单侧闭合性髌骨粉碎性骨折，受伤时间< 7 d。患者均对手术项目知情同意。
方法：根据患者意愿选择手术方式，将患者分为AO改良张力带固定组(n =22)、钛缆组(n =21)、聚髌器组(n=17)。AO改良张力带组中12例行AO改良张力带单纯内固定，10例行AO改良张力带内固定取出术；钛缆组均行钛缆环扎术；聚髌器组中10例行聚髌器单纯内固定术，7例行内固定取出术。
主要观察指标：①观察术后有无宿主及材料反应，比较术中出血量、住院医疗费用以及工作日损耗。②比较术后3个月患膝主动活动范围及术后6个月术后功能恢复情况及疗效。
结果：纳入患者60例均进入结果分析。①所有病例均未发生宿主或材料反应，聚髌器组患者术中出血量明显多于AO改良张力带单纯内固定组和钛缆组，工作日损耗少于AO改良张力带单纯内固定组，差异均有统计学意义（P < 0.05）；钛缆组住院医疗费用明显多于聚髌器及AO改良张力带单纯内固定组，差异有统计学意义（P < 0.05）。②钛缆组患者患膝活动度最大，平均108°左右，远期患膝功能评分最高，平均21.3分，优良率达95.2%，且没有明显严重并发症，均明显优于其它组别，差异有统计学意义（P < 0.05）。
结论：AO改良张力带固定与聚髌器固定治疗某些髌骨粉碎性骨折能达到优良效果。钛缆环扎法适合髌骨粉碎性骨折的治疗并可取得更好的膝关节功能恢复。
关键词：髌骨骨折；粉碎性骨折；内固定术
中图分类号: R318 文献标识码: A 文章编号: 1673-8225(2008)04-00760-05
李阳，欧阳跃平，苟三怀，袁文，刘岩，孙巍.三种不同内固定植入物治疗髌骨粉碎性骨折的效果比较[J].中国组织工程研究与临床康复, 2008，12(4):760-764
[www.zglckf.com/zglckf/ejournal/upfiles/07-4/4k-760(ps).pdf]
(Edited by Li Q/Qiu Y/Wang L)