CC Wu, WJ Chen Department of Orthopaedic Surgery, Chang Gung Memorial Hospital, Taoyuan, Taiwan

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1 Journal of Orthopaedic Surgery 2003: 11(2): inimally displaced intra-capsular femoral neck fractures in the elderly comparison of multiple threaded pins and sliding compression screws surgical techniques CC Wu, WJ Chen Department of Orthopaedic Surgery, Chang Gung emorial Hospital, Taoyuan, Taiwan ABSTRACT Purpose. To determine the outcome of treatment for minimally displaced femoral neck fractures using multiple threaded pins versus sliding compression screws for internal fixation. ethods. The medical records of 62 consecutive elderly patients with minimally displaced intra-capsular femoral neck fractures who underwent internal fixation of the fracture (37 with multiple threaded pins, and 25 with sliding compression screws) were reviewed. Clinical and radiological assessment of fracture healing at follow-up visits were noted. Results. In the 55 patients seen for follow-up at 3 months, 21.9% (n=7) of those treated by pinning demonstrated non-union of the fracture, and 0% of fractures treated with sliding compression screws (p=0.02). 46 patients were seen for follow-up at 1 year, with 10% (n=2) of those treated with sliding compression screws found to have osteonecrosis of the femoral head. The 2 fractures in the group treated by pinning demonstrating non-union at 3 months failed to unite by 1 year (p=0.11). 34 patients were seen for follow-up for at least 2 years, with no additional complications noted. Conclusion. Using sliding compression screws to treat minimally displaced femoral neck fractures can achieve a higher union rate than using pinning. The reason may be the better stability in the osteoporotic bone. However, osteonecrosis of the femoral head may occur with use of sliding compression screws because of greater intramedullary vascular damage as a result of wider reaming. Key words: bone screws; femoral neck fractures; pins, bone INTRODUCTION emoral neck fractures may be caused by either highenergy or low-energy injury, and are not uncommon. ost fractures are due to low-energy injury, such as from sliding down, and usually occur in elderly Address correspondence and reprint requests to: Dr Chi-Chuan Wu, Department of Orthopaedic Surgery, Chang Gung emorial Hospital, 5 u-hsin Street, 333, Kweishan, Taoyuan, Taiwan. ccwu@mail.cgu.edu.tw

2 130 CC Wu and WJ Chen Journal of Orthopaedic Surgery patients. ractures caused by high-energy injury (e.g. from motor vehicle accidents), usually occur in young patients and are relatively rare. 1 A femoral neck fracture may be intra-capsular (subcapital or transcervical) or extra-capsular (basal neck). Treatment and outcome for intra-capsular and extra-capsular lesions differ. 2 Although treatment of the latter is well defined, treatment of the former remains controversial. 1 Treatment of intra-capsular neck fractures in young patients by stable internal fixation as early as possible is favoured. 1,2 However, for elderly patients the fracture is not uncommon, and treatment depends on fracture type and either nonoperative or operative methods may be used. 3 5 Incomplete or impacted (Garden type I) fractures can be treated by non-operative methods, 4 and the favoured treatment for greatly displaced (Garden type III or IV) fractures is arthroplasty. 6 or minimally displaced (Garden type II) fractures, a method has yet to be consistently recommended. ultiple threaded pins or sliding compression screws () have achieved good results Practically, in terms of anatomic and biomechanical considerations, both techniques have advantages and disadvantages. However, in our opinion, should provide better holding power for intra-capsular neck fractures in elderly patients. 11 To the best of our knowledge, comparison between these techniques has rarely been undertaken, and thus it remains unclear which technique is superior. 8 The aim of this retrospective study was to investigate the treatment of minimally displaced femoral neck fractures using multiple threaded pins or, and to determine the relative advantages and disadvantages of each technique. ETHODS rom January 1994 to December 1998, 66 consecutive elderly (>65 years) patients with minimally displaced (Garden type II) intra-capsular femoral neck fractures were treated with internal fixation at our institution. Over this period, a total of 964 elderly patients with intra-capsular neck fractures of all 4 types were treated. The incidence of Garden type II fracture was therefore 6.8%. Extra-capsular and Garden types I, III, and IV intra-capsular neck fractures were excluded from this study. Pathologic fractures due to tumour invasion were also excluded. Inclusion criteria were age over 65 years, subcapital or transcervical fracture, lowenergy injury, and Garden type II non-displaced or minimally displaced fracture. our patients treated with cannulated screw were excluded due to the small case number. A total of 62 patients met the criteria for inclusion in the study. Subcapital or transcervical fractures were not considered separately because distinguishing between these sites on plain anteroposterior and lateral radiographs is always difficult. To distinguish between Garden types I and II, it was necessary to refer to both clinical features and radiographic findings. Generally, patients with Garden type I fractures can move and raise the ipsilateral lower extremity actively and without pain on passive movement, whereas this is not the case for patients with Garden type II fractures. 3 All 62 fractures were caused by low-energy injury, either by sliding down or falling to a sitting position. 23 (37.1%) patients had associated medical conditions at the time of the injury. Hypertension, diabetes mellitus, chronic lung diseases, chronic renal insufficiency, and previous cerebrovascular accident were the most common co-morbid conditions. Patient age ranged from 65 to 94 years (mean age, 73.4 years). 13 of the patients were male while the remaining were female (n=49), with a male-to-female ratio of 1:4. Surgery was arranged as soon as possible after admission, but not as an emergency procedure. All patients had surgery one to 5 days after injury, when the general condition was stable. Before surgery, immobilisation with skin traction was instituted to reduce hip pain. All operations were performed under spinal anaesthesia if possible, and patients were placed on the fracture table in the supine position. An image intensifier was routinely used to accurately insert the implants. The fractures did not require reduction. The choice of threaded pins or depended on the surgeon s preference. A total of 37 fractures were treated with multiple Knowles pins (Zimmer, Warsaw, US) and 25 fractures with (Zimmer, Warsaw, US). Three to 4 threaded pins were inserted for each patient, and the tip was placed as close to the articular surface as possible. The tip of the lag screw of the was also as close to the articular surface as possible. The location of the lag screw was inferior in the femoral head on the anteroposterior view and central on the lateral view in the image intensifier. 12 No pin or screw was added to the fixation. Drain insertion was used for patients with treatment but not for those having multiple Knowles pins inserted. Postoperatively, patients were encouraged to ambulate as early as possible. The majority of patients used a frame, but a wheelchair was provided for patients having difficulty with standing. Patients were seen for follow-up at the out-patient clinic at 4- to 6- week intervals. The clinical and radiographic state of fracture healing was recorded. After the fracture had

3 Vol. 11 No. 2, December 2003 Intra-capsular femoral neck fractures 131 Table Clinical data for 62 elderly patients treated for minimally displaced femoral neck fracture Case No. Age (years)/sex 1 5/ 2 7/ 3 2/ 4 8/ 5 8/ 6 4/ 7 2/ 8 8/ Treatment method Pi * 6 n / / 13 80/ / 16 76/ 17 88/ / / / 24 65/ 25 74/ / 28 76/ / Result at 3 months Non-union LS LS LS Result at 1 year urther surgery (time) ollow-up (years) S CS (6 months) 5. 5 Osteonecrosis N/ A N/ A Osteonecrosis 4.7 (8 months) 4. 5 <2 (8 months) (2 months) <2 (10 months) healed, patients were advised to make appointments for follow-up annually and when necessary. racture union was defined clinically as when there was no complaint of pain or tenderness, and when the patient could ambulate at the pre-injured state. Radiographically, fracture union was defined as when trabeculae had bridged fracture fragments. 13 A nonunion was defined as non-union one year after treatment, or that implant stability was lost and repeated surgery was necessary to achieve ambulation. 14 isher s exact test was used for statistical analysis, and p<0.05 was considered statistically significant. RESULTS No patient died during the hospital stay. The average hospital stay was 10 days (range, 5 23 days). Of the total 62 patients, 55 patients (32 treated with Knowles pins, and 23 treated with ) attended follow-up at

4 132 CC Wu and WJ Chen Journal of Orthopaedic Surgery Table (cont d) Case No. Age (years)/sex Treatment method Result at 3 months Result at 1 year urther surgery (time) ollow-up (years) 32 66/ 33 91/ 34 72/ 35 69/ / 38 78/ 39 77/ 40 89/ 41 74/ 42 66/ 43 66/ / 46 78/ 47 65/ 48 70/ / 51 72/ 52 70/ 53 66/ 54 73/ 55 73/ 56 67/ 57 76/ 58 65/ 59 72/ / 62 84/ Non-union LS LS Excision 3. 5 Excision 3.4 (10 months) (1 month) (1 month) * Knowles pin sliding compression screw lost for follow-up LS lost fragment stability Excision excision arthroplasty N/A not applicable 3 months. The remaining 7 patients included 2 deaths which were not related to the surgery, and 5 lost to follow-up (Table). ive of the 32 patients treated with Knowles pins lost fragment stability, including 3 who were treated with arthroplasty immediately (cases 22, 40, and 52), and 2 (cases 17 and 29) whose arthroplasty was delayed because of patients initial hesitation. Two more patients treated with Knowles pins demonstrated non-union at 3-month follow-up, while the remaining 25 fractures healed uneventfully. The rate of delayed union at 3 months was 21.9%. All 23 cases healed within 3 months, with a rate of

5 Vol. 11 No. 2, December 2003 Intra-capsular femoral neck fractures 133 delayed union of 0% (p=0.02). There were no wound infections in either group. At one year postoperatively, 46 patients (26 treated with Knowles pins, and 20 with s) were seen for follow-up. our more patients had died and 5 further patients were lost for follow-up despite all efforts. The 2 cases treated with Knowles pins with delayed union at 3 months remained unchanged but pin migration had occurred. One was successfully treated with. The other patient had a planned arthroplasty, but deep infection with frank pus was found intra-operatively, and excision arthroplasty had to be performed (ig. 1). Two cases treated with (cases 8 and 27) had progressive osteonecrosis of the femoral head, which was evident on plain radiographs at 8 and 11 months, respectively (p=0.11). One of these patients was treated with arthroplasty because of severe pain. The other was continuously observed without surgery, despite a mild limp over a follow-up period of 3.6 years (ig. 2). A total of 34 patients (19 treated with Knowles pins and 15 with ) were seen for follow-up for at least 2 years (range, years). There were no further wound infections or instances of osteonecrosis of the femoral head. 12 patients sustained contralateral hip fractures, and were treated with arthroplasty or immediately. No complications occurred among these patients. At the last follow-up, 32 patients could walk without aids, and had completely recovered to pre-injury levels of daily activity. However, 2 patients were wheelchair-dependent as a result of cerebrovascular accidents. DISCUSSION Despite the fact that intra-capsular femoral neck fractures in the elderly are not uncommon, minimally igure 1 Case 34: A 72-year-old man with a left femoral neck fracture treated with Knowles pins. migration occurred and deep infection was found during revision surgery. Excision arthroplasty was subsequently performed.

6 134 CC Wu and WJ Chen Journal of Orthopaedic Surgery displaced fractures are rarely reported. In this series, an incidence rate of 6.8% was noted. Only a small number of cases have been reported in the literature and an appropriate treatment method has therefore not been recommended. Both threaded pinning and have their supporters actors favouring fracture healing include minimal gap, adequate stability, and sufficient nutrition supply. 15 In treating minimally displaced intracapsular neck fractures, local stability should be assumed the most important role. The effects of gap and nutrition supplies are usually less problematic due to minimal displacement of fragments. When elderly patients sustain fractures from low-energy injuries, the local bone must be very osteoporotic. Internal fixation, therefore, runs a high risk of migration. The function of threaded pins in treating femoral neck fractures is to provide supporting stability. 2,16 The fracture site usually cannot be compressed. Therefore, a gap always exists and load transfer must be through implants. With the added presence of local osteoporotic bone, the risk of implant migration is high. In this series, loss of fixation stability occurred in 15.6% of patients treated with threaded pins in 3 months. Conversely, with stabilisation, the fracture gap can be reduced by local compression either intraoperatively or postoperatively. Load transfer is through both bone and implant. urthermore, the thread of the lag screw is much wider, which greatly increases its holding power. 11,17 Local stability is therefore much better. In this series, no fixation failure was found with treatment. The blood supply of the femoral head has been well studied. Although 3 sources of blood vessels are described, there is variation between patients. The ascending branches from the arterial ring at the base igure 2 Case 27: A 69-year-old woman with a right femoral neck fracture treated with sliding compression screws. Although the fracture healed within 3 months, osteonecrosis of the femoral head was seen at 11 months. No further surgery was performed over a 3-year follow-up period because the only complaint was a mild limp.

7 Vol. 11 No. 2, December 2003 Intra-capsular femoral neck fractures 135 of the neck are considered the most important. 1,18 In minimally displaced fractures, blood supply from the ascending branches, the ligamentum teres, and the nutrient artery in the marrow cavity are less compromised. The incidence of osteonecrosis of the femoral head should be low in Garden type II fractures. However, reaming to insert a lag screw of the has been reported to destroy the intramedullary vessels. 19 In this series, at 1-year follow-up, 2 out of 20 fractures treated with resulted in osteonecrosis of the femoral head, compared with none of those treated with Knowles pins (p=0.11). Therefore, despite the fact that is reported to have great success in treating subcapital or transcervical neck fractures, 20 the risk of osteonecrosis of the femoral head may be higher than that with treatment by pinning, especially in elderly patients. It has been suggested that should be supplemented with a de-rotation screw to ensure stability. 1,9 Biomechanical considerations however, might suggest that this is harmful. With pins to support fracture fragments, the compression effect induced by a lag screw will be greatly reduced. oreover, there is a high risk of pin penetration into the joint space once ambulation with weightbearing commences. The complication rate may thus increase with use of this modification. Long-term and complete follow-up of elderly patients is usually difficult. The postoperative mortality rate for hip fractures has been reported at 10% 46% in the first year, and the follow-up rate to greatly decrease thereafter. 21 In this series, 88.7% of patients were seen for follow-up at 3 months and the union rate for was significantly better than that seen with pinning (p=0.02). However, the complication rate with requires much longer follow-up overall. 1 At one year, only a 74.2% follow-up rate was achieved. Observation for osteonecrosis of the femoral head in femoral neck fractures requires follow-up of more than 2 years. In this series, only 54.8% patients were seen for follow-up at more than 2 years, and thus the rate of osteonecrosis noted may not be accurate for this group as a whole. However, it was clearly demonstrated that the short-term union rate was much higher with treatment than with pinning, and that patients with achieved earlier ambulation. CONCLUSION inimally displaced intra-capsular femoral neck fractures in the elderly are uncommon. Internal fixation with as early as possible can achieve a better initial outcome. Patients can ambulate with walking aids almost immediately after surgery. ractures are usually healed within 3 months. However, there is a risk of osteonecrosis of the femoral head. If this occurs, arthroplasty can be performed to achieve complete recovery. REERENCES 1. Swiontkowski. Intracapsular fractures of the hip. J Bone Joint Surg Am 1994;76: Sisk TD. ractures of hip and pelvis. In: Crenshaw AH, editor. Campbell s operative orthopedics. St. Louis: CV osby; 1987: Chiu Y, Lo WH. Undisplaced femoral neck fracture in the elderly. Arch Orthop Trauma Surg 1996;115: Hansen BA, Solgaard S. Impacted fractures of the femoral neck treated by early mobilization and weight-bearing. Acta Orthop Scand 1978;49: Linde, Andersen E, Hvass I, adsen, Pallesen R. Avascular femoral head necrosis following fracture fixation. Injury 1986;17: Bray TJ, Smith-Hoefer E, Hooper A, Timmerman L. The displaced femoral neck fracture. Internal fixation versus bipolar endoprosthesis. Results of a prospective, randomized comparison. Clin Orthop 1988;230: Bentley G. Treatment of nondisplaced fractures of the femoral neck. Clin Orthop 1980;152: Kuokkanen H, Korkala O, Antti-Poika I, Tolonen J, Lehtimaki Y, Silvennoinen T. Three cancellous bone screws versus a screw-angle plate in the treatment of Garden I and II fractures of the femoral neck. Acta Orthop Belg 1991;57: Ort PJ, Laont J. Treatment of femoral neck fractures with a sliding compression screw and two Knowles pins. Clin Orthop 1984;190: Springer ER, Lachiewicz P, Gilbert JA. Internal fixation of femoral neck fractures. A comparative biomechanical study of Knowles pins and 6.5-mm cancellous screws. Clin Orthop 1991;267: Asnis SE, Ernberg JJ, Bostrom P, Wright T, Harrington R, Tencer A, et al. Cancellous bone screw thread design and holding power. J Orthop Trauma 1996;10: Wu CC, Shih CH. Biomechanical analysis of dynamic hip screw in the treatment of intertrochanteric fractures. Arch Orthop Trauma Surg 1991;110: Tooke S, avero KJ. emoral neck fractures in skeletally mature patients, fifty years old or less. J Bone Joint Surg Am 1985; 67:

8 136 CC Wu and WJ Chen Journal of Orthopaedic Surgery 14. Ballmer T, Ballmer P, Baumgaertel, Ganz R, ast JW. Pauwels osteotomy for nonunions of the femoral neck. Orthop Clin North Am 1990;21: Karlstrom G, Olerud S. ractures of the tibial shaft; a critical evaluation of treatment alternatives. Clin Orthop 1974;105: Booth KC, Donaldson TK, Dai QG. emoral neck fracture fixation: a biomechanical study of two cannulated screw placement techniques. Orthopedics 1998;21: Harkess JW, Ramsey WC, Ahmadi B. Principles of fractures and dislocations. In: Rockwood CA Jr, Green DP, editors. Rockwood and Green s fractures in adults. Philadelphia: JB Lippincott; 1984: DeLee JC. ractures and dislocations of the hip. In: Rockwood CA Jr, Green DP, editors. Rockwood and Green s fractures in adults. Philadelphia: JB Lippincott, 1984; Brodetti A. The blood supply of the femoral neck and head in relation to the damaging effects of nails and screws. J Bone Joint Surg Br 1960,42: Skinner PW, Powles D. Compression screw fixation for displaced subcapital fracture of the femur. Success or failure? J Bone Joint Surg Br 1986;68: Holmberg S, Conradi P, Kalen R, Thorngren KG. ortality after cervical hip fracture: 3002 patients followed for 6 years. Acta Orthop Scand 1986;57:8 11.