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Use of the Talon Hip Compression Screw in Intertrochanteric Fractures of the Hip

Bramlet, Dale, G

Section Editor(s): Strauss, Elton MD

Clinical Orthopaedics and Related Research: August 2004 - Volume 425 - Issue - p 93-100
doi: 10.1097/01.blo.0000132628.90667.e6
SECTION I: SYMPOSIUM: Geriatrics in Orthopaedics
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SDC

A retrospective analysis of a compression hip screw with four reversibly deployable talons was done. Fifty-four patients had sufficient radiographs to be included in this analysis. One-year mortality was 17% and increased to 41% by 2 years. No lag screws cut out, and postoperative slide was reduced compared with that in many published series. Three patients had revision of a failed alternate-type hip pin with the Talon hip compression screw. Previous studies showed the talons provide the definitive difference in allowing enhanced compression at the time of surgery, preventing cut-out by enhanced rotational stability, and allowing immediate postoperative weightbearing without excessive limb shortening. The failure mode of the Talon compression hip screw seems to be side-plate loosening rather than varus deformity and lag screw cut-out. The Talon compression hip screw especially is effective with weak, osteoporotic bone and in unstable, three-part and four-part fractures. A previous study showed that Talon deployment notably improved interfragment compression and torsional strength, and that engagement or penetration into or through the cortical bone at the base of the femoral head-neck junction in the inferior lag screw position was the critical technical step to maximize the talon lag screw purchase.

From All Florida Orthopaedic Associates, St. Petersburg, FL.

The device that is the subject of this manuscript is FDA approved.

Funded in part by Orthopedic Designs Incorporated, St. Petersburg, FL. The author has stock and options in the company.

Correspondence to: Dale Bramlet, MD, All Florida Orthopaedic Associates, P.O. Box 76359, St. Petersburg, FL 33734. Phone: 727-369-5030; Fax: 727-369-5069; E-mail: dbramle1@tampabay.rr.com.

Guest Editor

The advantages of treatment by open reduction and internal fixation (ORIF) for intertrochanteric fractures of the proximal femur are known. Rigid internal fixation with interfragmentary compression permits early mobilization and reduces patient morbidity and mortality.40,47,57,69 The hip compression screw allows the fracture site to collapse on itself as patients ambulate versus having the lag screw erode through the bone and penetrate into the hip.1,34,50,67 With excessive lag screw slide, the threads of the lag screw impinge against the barrel, effectively converting a sliding screw into a fixed angle device.7,73 Sliding mainly occurs during the first 2 postoperative weeks, and excessive sliding has been associated with a delay in union of the fracture52 and lag screw cut-out.73 Technical failure, defined as loss of fixation, loosening of the lag screw, excessive slide, varus deformity, and/or cut-out of the screw with hip penetration may occur in 4–19% of patients.10,51,65,70

Unstable fractures with a large posterior spike of bone and/or medial comminution particularly are challenging, and medial displacement,29,31 valgus osteotomies,13,24,61 and less invasive technologies21,32,33 have been proposed for restoring stability. Anatomic reduction and rigid internal fixation with a compression screw plate system currently is the technique preferred by investigators.12,19,25,30,63 Larsson et al39 reported that 30–65% of all intertrochanteric fractures were unstable. With weak osteoporotic bone, with reverse obliquity, and in unstable, comminuted three-part and four-part intertrochanteric fractures, varus angulation of the fracture fragments, failure of fixation, and joint penetration rates of 8–50% have been reported.28,36,43,49

The Talon hip compression screw incorporates a reversibly deployable series of four talons that protrude from the base of the threads of the lag screw (Fig 1). The talons are designed to engage in the cortical bone at the base of the femoral head-neck junction in the inferior portion of the femoral head. A previous biomechanical study showed that engagement of the talons into the dense cortical bone serves to considerably enhance the purchase of the lag screw within the femoral head. Even in instances where the talons have been subjected to supraphysiologic forces, they can be completely reversed within the lag screw for subsequent removal, if necessary.8 The talons effectively double the purchase strength of the lag screw in the femoral head, enabling the surgeon to tighten the compression screw with greater force without the lag screw stripping out. Furthermore, the talons triple the resistance to peak torque forces between the femoral head and the lag screw, and considerably prevent migration of the lag screw subjected to torsional forces. By increasing the amount of bone engaged by the screw, particularly the dense cortical bone at the base of the femoral neck, theoretically it should resist joint penetration by increasing the column of bone necessary for a lag screw to penetrate through before perforating the femoral head and entering the hip.

Fig 1.

Fig 1.

Because the final location of the lag screw relative to the femoral head geometry has been shown to be substantial in terms of failure,2,3,5,16,18,27,68 the location of the lag screw in the femoral head was measured to assess migration. In cases of severe osteoporosis, excessive tightening of the compression screw can lead to a stripping of the thread purchase in the bone of the femoral head and subsequent loss of fixation. Increasing the strength of attachment of the lag screw in the femoral head (or the purchase of the lag screw) can enable greater compressive forces to be applied across the fracture site. With appropriate lag screw length choice, greater initial compression at the fracture site should result in less settling of the lag screw, and therefore, less chance of lag screw thread–barrel engagement.45,60 The purpose of this study was to investigate the clinical performance of a compression hip screw with four reversibly deployable talons.

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MATERIALS AND METHODS

All patients with hip fractures treated in one orthopaedic group practice with the Talon hip compression screw during the year 2000 were reviewed. Of the 81 patients who received the device, eight were excluded because they died within 3 months postoperatively. An additional 12 patients were excluded because they did not meet radiographic criteria, which were defined as postoperative radiographs within the first 5 days after surgery, followup radiographs at 6 and 12 weeks, and final radiographs. Nine patients had femoral neck fractures and were excluded. Fifty-four patients had sufficient data to be included in this analysis.

Radiographs taken at final followup (or at the time of union if followup radiographs could not be obtained) were compared with initial postoperative films. Radiographic data were analyzed using four criteria: sliding of the lag screw, distance from lag screw tip to superior femoral cortex, distance from lag screw tip to femoral head apex, and femoral neck-shaft angle.

Radiographs (Fig 2) were analyzed using digital calipers, loupe magnification, and correction for radiographic magnification. Magnification correction was by measurement of the distance of three thread peaks (TL), corresponding to a known distance (9.53 mm). The correction factor formula was as follows:

Fig 2.

Fig 2.

Fractures were classified using a modified Evan’s classification system.22,23,38 The degree of osteoporosis was calculated using the Singh index, which classifies trabecular bone structure in the proximal femur.37 Grades 1–3 were considered osteoporotic. All measurements and classifications were made by a single observer (DB). The percentage of opposable bone of the major proximal fragment and the distal shaft in the AP and lateral radiographic planes was estimated.

Data were analyzed using SPSS, version 11.0 (SPSS, Inc, Chicago, IL). Differences between postoperative and followup radiographs were analyzed using a paired samples t test.

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RESULTS

The analysis of patient demographics revealed an elderly population with osteoporosis predominantly displaced fractures. There were 16 men and 38 women in the study. The average age of the patients at the time of fracture was 78 ± 18 years (range, 10–99 years). Clinical followup ranged from 1 to 3 years. Sixty-four percent of the patients were classified as having osteoporosis according to the Singh index (25%, 18% 21% 11%, 5%, and 11% classified as index 1, 2, 3, 4, 5, 6, respectively). Nine percent could not be indexed because of inadequate radiographs of the contralateral uninjured hip. There were 28 right and 26 left fractures. Fracture classifications included two-part (34%), three-part (32%), four-part (17%), and intertrochantericsubtrochanteric (17%) fractures. Ninety-five percent of the fractures were displaced and 38% were unstable. Reduction apposition of major fragments averaged 92 ± 12%.

Comparison of measurements revealed minimal change in the position of the lag screw at followup. The difference in the means of the data sets were clinically insignificant for change in the relative position of the lag screw in the femoral head or loss of reduction angle, even in fractures in osteoporotic bone (Table 1).6,36,46,52 Compression obtained at the time of fracture fixation resulted in minimal subsequent lag screw slide (average, 5.8 mm). Results from the current study showed substantially less slide than in other series,36,52 reflecting the enhanced compression obtained at the time of fracture fixation. Postoperative slide increased in unstable, Evan’s Type 4 and 5 fractures (Table 2).

Table 1

Table 1

Table 2

Table 2

Final functional assessments at an average of 17 months followup showed that 69% of patients who were unlimited community ambulators preoperatively retained their prefracture ambulatory status. All 54 patients were followed until radiographic union. Final followup at a minimum of 1 year was done to assess the patients’ return to prefracture status. No patients with intertrochanteric fractures had osteonecrosis develop. One patient had a refracture after a second fall 16 months later and healing was achieved after repinning (Fig 3). Three patients had revision of a failed alternate-type hip pin with a Talon compression hip screw. No patients with intertrochanteric fractures had cut-out of the lag screw, and all patients except one achieved healing. This patient, who had quadriplegia, had resection of the proximal femur for overwhelming sepsis 7 days postoperatively. Mortality rates were 17% at 1 year (average age, 88 years) and increased to 41% at 2 years.

Fig 3.

Fig 3.

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DISCUSSION

Numerous authors have addressed ideal positioning of the lag screw in the femoral head to maximize purchase of the screw and to minimize the risk of cut-out.44,65,71 Based on biomechanical data,8 inferior placement of the lag screw in the lower portions of the femoral head is recommended, because this results in greater purchase of the lag screw regardless of whether the talons are deployed. Technical experience with this product has shown that one of the critical factors maximizing the purchase of the lag screw in the femoral head is engagement of the talons in the dense cortical bone at the junction between the femoral head and the neck.8

The mechanism of failure accounting for lag screw cut-out and subsequent pin penetration is multifactorial. Gill et al26 reported that high stresses in the surrounding cancellous bone contribute to the failure of repairs. Failure to compress the fracture site fully has been accompanied by excessive slide of the lag screw, which has been shown to be associated with a poor functional outcome.6 The advantages of enhanced compression across the fracture site have been cited by numerous authors.41,42,55 Excessive slide, presumably associated with poor initial compression, has been shown to prolong time to union of operatively treated intertrochanteric fractures.52 Before the introduction of a hip pinning system with talons, few were designed to prevent rotation forces between the lag screw and the proximal femoral bone. Hip bolt procedures have been advocated by some to increase the purchase of the device in the femoral head,59 whereas others have advocated the use of intramedullary nails.4,9,14,15,35,56,66 However, the hip compression screw remains the most popular method of treatment of these often challenging fractures.17,20,46,53,58,74 There are no comparative studies to date testing different commercially available hip pinning systems with and without hip pins with talons.

Thread length and screw designs vary among manufacturers and have been shown to be important factors in preventing cut-out in biomechanical testing of hip compression screws.62,64 The average thread-length of the Talon lag screw is longer, and the major diameter of the threads is larger than most standard, commercially available products. Biomechanical data have shown that the talons are the key element, allowing a doubling of compression forces at the time of internal fixation of a stable, two-part intertrochanteric fracture.8

Some current hip pinning systems do not adequately address rotational or torque forces that occur between the femoral head and the lag screw as the patient ambulates and arises from or resumes the sitting position.48 One might postulate that, with weakened osteoporotic bone, the lag screw acts like a wedge, slowly working its way upward as the patient ambulates and subjecting their recently fractured hip to rotational forces. These rotational forces are particularly a problem in patients who are noncompliant and slightly demented, but who are ambulatory. Some authors have noted extreme resorption of bone in the femoral head and metaphyseal regions of the proximal femur, and torsional forces have been implicated in implant failure.6,64 Enlarged thread patterns or expansile devices, such as molley–bolt designed hip lag screws, fail to reach to the dense remaining cortical bone that likely holds the greatest promise for maximizing purchase of the lag screw in the femoral head. Furthermore, using a screw driver, the talons can be variably and reversibly deployed at the surgeon’s discretion up to a maximum of 1.2 inches. Many standard lag screws have an external thread diameter of approximately 0.5 inches. Therefore, the column of bone that a lag screw must erode through to penetrate through the superior cortex of the femoral head is more than doubled by using the hip pin with talons deployed.

The radiographic and clinical results of a new compression hip screw with retractable talons provided purchase in difficult hip fractures in elderly patients with osteoporosis without lag screw cut-out or change in angle of fracture reduction (average, 2°). Compression obtained at the time of fracture fixation resulted in minimal subsequent lag screw slide (average, 5.8 mm). Results from the current study showed substantially less slide than in other series36,52 reflecting the enhanced compression obtained at the time of fracture fixation. All talons deployed satisfactorily, and the clinical and radiographic results were gratifying. Mortality rates were not improved by this technique compared with other series of hip fractures,4 reflecting the geriatric nature of the patient population.

Results of the current study and of a previous study8 support the conclusion of Wu et al71 that the optimal location of any lag screw is with an axis inferior to the center of the femoral head. This placement leads to greater purchase of the lag screw in the femoral head in an area that presumably has more dense bone, and theoretically should resist cut-out. Deployment of the talons into or through the cortical endosteal surface increases the purchase strength of the lag screw in this inferior position.

There are several limitations to this retrospective study. Precise determinations of time to radiographic union were not possible because of the limited number of radiographs that were available. Radiographic measurements and classifications were made by one observer, and tests of intraobserver reliability were not done. However, for the Singh index, intraobserver variation is reported to have substantial strength of agreement.37

The resistance to torque forces is the critical factor leading to the failure of hip pins in osteoporotic bone.48,54,64,72 As the patient ambulates in the early postoperative period, the repetitive torque and loading forces are paramount in leading to a wedge effect of the lag screw in the minimally dense femoral head. Compression at the fracture site is critical to preventing subsequent excessive slide of the lag screw as the patient ambulates in the postoperative period.11 Furthermore, talon deployment seems to be the critical factor in resisting rotational torque forces about the femoral head. Although results from the current study did not address the degree of talon penetration into the dense cortical bone, because of my substantial clinical experience with this device, it seems to me that engagement or penetration into or through the cortical bone at the base of the femoral head–neck junction is the critical technical step to maximizing the talon purchase in the femoral head.

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Acknowledgments

I want to acknowledge the support of my colleagues at All Florida Orthopaedics, Inc., and the assistance of Jane Carver, PhD, and Connie Stevens, in preparing this manuscript.

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References

1. Alho A, Molster A, Raugstad TS, et al. Sliding of the compression hip screw in femoral neck fractures. J Orthop Trauma. 1987;1:293–297.
2. Arrington ED, Davino NA. Subcapital femoral neck fracture after closed reduction and internal fixation of an intertrochanteric hip fracture: A case report and review of the literature. Am J Orthop. 1999;28:517–521.
3. Baker DM. Fractures of the femoral neck after healed intertrochanteric fractures: A complication of too short a nail plate fixation: Report of three cases. J Trauma. 1975;15:73–81.
4. Baumgaertner M, Curtin S, Lindskog D. Intramedullary versus extramedullary fixation for the treatment of intertrochanteric hip fractures. Clin Orthop. 1998;348:87–94.
5. Baumgaertner MR, Solberg BD. Awareness of tip-apex distance reduces failure of fixation of trochanteric fractures of the hip. J Bone Joint Surg. 1997;79B:969–971.
6. Bendo JA, Weiner LS, Strauss E, Yang E: Collapse of intertrochanteric hip fractures fixed with sliding screws. Orthop Rev Suppl:30–37, 1994.
7. Bonamo JJ, Accettola AB. Treatment of intertrochanteric fractures with a sliding nail-plate. J Trauma. 1982;22:205–215.
8. Bramlet D, Wheeler D. Biomechanical evaluation of a new type of hip compression screw with retractable talons. J Orthop Trauma. 2003;17:618–624.
9. Bridle S, Patel A, Bircher M, et al. Fixation of intertrochanteric fractures of the femur: A randomised prospective comparison of the gamma nail and the dynamic hip screw. J Bone Joint Surg. 1991;73B:330–334.
10. Buciuto R, Hammer R. RAB-plate versus sliding hip screw for unstable trochanteric hip fractures: Stability of the fixation and modes of failure: Radiographic analysis of 218 fractures. J Trauma. 2001;50:545–550.
11. Cameron HU, Graham JD. Retention of the compression screw in sliding screw plate devices. Clin Orthop. 1980;146:219–221.
12. Chang WS, Zuckerman JD, Kummer FJ, et al. Biomechanical evaluation of anatomic reduction versus medial displacement osteotomy in unstable intertrochanteric fractures. Clin Orthop. 1987;225:141–146.
13. Clark DW, Ribbans WJ. Treatment of unstable intertrochanteric fractures of the femur: A prospective trial comparing anatomical reduction and valgus osteotomy. Injury. 1990;21:84–88.
14. Curtis M, Jinnah R, Wilson V, et al. Proximal femoral fractures: a biomechanical study to compare intramedullary and extramedullary fixation. Injury. 1994;25:99–104.
15. Davis T, Sher J, Checketts R, et al. Intertrochanteric fractures of the femur: A prospective study comparing the use of the Kuntscher-Y nail and a sliding hip screw. Injury. 1988;19:421–426.
16. Davis TR, Sher JL, Horsman A, et al. Intertrochanteric femoral fractures: Mechanical failure after internal fixation. J Bone Joint Surg. 1990;72B:26–31.
17. De PL, Specchia N, Rizzi L, et al. Critical analysis of intramedullary nailing by the Ender method in the treatment of intertrochanteric fractures. Ital J Orthop Traumatol. 1993;19:25–31.
18. Den Hartog BD, Bartal E, Cooke F. Treatment of the unstable intertrochanteric fracture: Effect of the placement of the screw, its angle of insertion, and osteotomy. J Bone Joint Surg. 1991;73A:726–733.
19. Desjardins AL, Roy A, Paiement G, et al. Unstable intertrochanteric fracture of the femur: A prospective randomised study comparing anatomical reduction and medial displacement osteotomy. J Bone Joint Surg. 1993;75B:445–447.
20. Doppelt S. The sliding compression screw—today’s best answer for stabilization of intertrochanteric hip fractures. Orthop Clin North Am. 1980;11:507–523.
21. Dujardin FH, Benez C, Polle G, et al. Prospective randomized comparison between a dynamic hip screw and a mini-invasive static nail in fractures of the trochanteric area: Preliminary results. J Orthop Trauma. 2001;15:401–406.
22. Evans E. The treatment of trochanteric fractures of the femur. J Bone Joint Surg. 1949;31B:190–203.
23. Evans E. Trochanteric fractures: A review of 110 cases treated by nail-plate fixation. J Bone Joint Surg. 1951;33B:192–204.
24. Fontanesi G, Costa P, Giancecchi F, et al. Intertrochanteric valgus osteotomy and sliding compression hip screw in fractures of the femoral neck. Ital J Orthop Traumatol. 1991;17:293–304.
25. Gargan MF, Gundle R, Simpson AH. How effective are osteotomies for unstable intertrochanteric fractures? J Bone Joint Surg. 1994;76B:789–792.
26. Gill JM, Johnson GR, Sher JL, et al. Biomechanical aspects of the repair of intertrochanteric fractures. J Biomed Eng. 1989;11:235–239.
27. Gundle R, Gargan MF, Simpson AH. How to minimize failures of fixation of unstable intertrochanteric fractures. Injury. 1995;26:611–614.
28. Haidukewych GJ, Israel TA, Berry DJ. Reverse obliquity fractures of the intertrochanteric region of the femur. J Bone Joint Surg. 2001;83A:643–650.
29. Harper MC. The treatment of unstable intertrochanteric fractures using a sliding screw-medial displacement technique. J Trauma. 1982;22:792–796.
30. Hopkins CT, Nugent JT, Dimon JHI. Medial displacement osteotomy for unstable intertrochanteric fractures: Twenty years later. Clin Orthop: 169–172, 1989.
31. Hunter GA, Krajbich IJ. The results of medial displacement osteotomy for unstable intertrochanteric fractures of the femur. Clin Orthop. 1978;137:140–143.
32. Ingman AM. Percutaneous intramedullary fixation of trochanteric fractures of the femur: Clinical trial of a new hip nail. Injury. 2000;31:483–487.
33. Janzing HM, Houben BJ, Brandt SE, et al. The Gotfried Percutaneous Compression Plate versus the Dynamic Hip Screw in the treatment of pertrochanteric hip fractures: Minimal invasive treatment reduces operative time and postoperative pain. J Trauma. 2002;52:293–298.
34. Jensen JS, Tondevold E, Sonne-Holm S. Stable trochanteric fractures: A comparative analysis of four methods of internal fixation. Acta Orthop Scand. 1980;51:811–816.
35. Juhn A, Krimerman J, Mendes D. Intertrochanteric fracture of the hip: Comparison of nail-plate fixation and Ender’s nailing. Arch Orthop Trauma Surg. 1988;107:136–139.
36. Kim WY, Han Y, Park JL, et al. Failure of intertrochanteric fracture fixation with a dynamic hip screw in relation to pre-operative fracture stability and ostoporosis. Int Orthop. 2001;25:360–362.
37. Koot VC, Kesselaer SM, Clevers GJ, et al. Evaluation of the Singh index for measuring osteoporosis. J Bone Joint Surg. 1996;78B:831–834.
38. Kyle R. Intertrochanteric Fractures. In Chapman M (ed): Operative Orthopaedics. Vol. 1. Philadelphia, JB Lippincott Company, 353–359, 1988.
39. Larsson S, Friberg S, Hansson LI. Trochanteric fractures: Influence of reduction and implant position on impaction and complications. Clin Orthop. 1990;260:130–139.
40. Laskin RS, Gruber MA, Zimmerman AJ. Intertrochanteric fractures of the hip in the elderly: A retrospective analysis of 236 cases. Clin Orthop. 1979;141:188–195.
41. Lunsjo K, Ceder L, Stigsson L, et al. Two-way compression along the shaft and the neck of the femur with the Medoff sliding plate: One-year follow-up of 108 intertrochanteric fractures. J Bone Joint Surg. 1996;78B:387–390.
42. Lunsjo K, Ceder L, Thorngren K, et al. Extramedullary fixation of 569 unstable intertrochanteric fractures: A randomized multicenter trial of the Medoff sliding plate versus three other screw-plate systems. Acta Orthop Scand. 2001;72:133–140.
43. Madsen JE, Naess L, Aune AK, et al. Dynamic hip screw with trochanteric stabilizing plate in the treatment of unstable proximal femoral fractures: A comparative study with the Gamma nail and compression hip screw. J Orthop Trauma. 1998;12:241–248.
44. Mainds CC, Newman RJ. Implant failures in patients with proximal fractures of the femur treated with a sliding screw device. Injury. 1989;20:98.
45. Manoli A. Malassembly of the sliding screw-plate device. J Trauma. 1986;26:916–922.
46. Meislin R, Zuckerman J, Kummer F, et al. A biomechanical analysis of the sliding hip screw: The question of plate angle. J Orthop Trauma. 1990;4:130–136.
47. Miller K, Atzenhofer K, Gerber G, et al. Risk prediction in operatively treated fractures of the hip. Clin Orthop. 1993;293:148–152.
48. Mohan R, Karthikeyan R, Sonanis S. Dynamic hip screw: Does side make a difference? Effects of clockwise torque on right and left DHS. Injury. 2000;31:697–699.
49. Moller BN, Lucht U, Grymer F, et al. Instability of trochanteric hip fractures following internal fixation: A radiographic comparison of the Richards sliding screw-plate and the McLaughlin nail-plate. Acta Orthop Scand. 1984;55:517–520.
50. Mulholland RC, Gunn DR. Sliding screw plate fixation of intertrochanteric femoral fractures. J Trauma. 1972;12:581–591.
51. Nagi ON, Dhillon MS, Goni VG. Open reduction, internal fixation and fibular autografting for neglected fracture of the femoral neck. J Bone Joint Surg. 1998;80B:798–804.
52. Nakata K, Ohzono K, Hiroshima K, et al. Serial change of sliding in intertrochanteric femoral fractures treated with sliding screw system. Arch Orthop Trauma Surg. 1994;113:276–280.
53. O’Brien P, Meek R, Blachut P, et al. Fixation of intertrochanteric hip fractures: Gamma nail versus dynamic hip screw: A randomized, prospective study. Can J Surg. 1995;38:516–520.
54. Olsson O. Alternative techniques in trochanteric hip fracture surgery: Clinical and biomechanical studies on the Medoff sliding plate and the Twin hook. Acta Orthop Scand Suppl. 2000;295:1–31.
55. Olsson O, Ceder L, Hauggaard A. Femoral shortening in intertrochanteric fractures: A comparison between the Medoff sliding plate and the compression hip screw. J Bone Joint Surg. 2001;83B:572–578.
56. Park S, Kang J, Kim H, et al. Treatment of intertrochanteric fracture with the Gamma AP locking nail or by a compression hip screw: A randomised prospective trial. Int Orthop. 1998;22:157–160.
57. Pitsaer E, Samuel AW. Functional outcome after intertrochanteric fractures of the femur: Does the implant matter? A prospective study of 100 consecutive cases. Injury. 1993;24:35–36.
58. Rao J, Hambly M, King J, et al. A comparative analysis of Ender’s-rod and compression screw and side plate fixation of intertrochanteric fractures of the hip. Clin Orthop. 1990;256:125–131.
59. Rao JP, Alber GC, Gutteling E. Clinical evaluation of the Alta hip bolt in peritrochanteric hip fractures. Am J Orthop. 1998;27:612–616.
60. Rha JD, Kim YH, Yoon SI, et al. Factors affecting sliding of the lag screw in intertrochanteric fractures. Int Orthop. 1993;17:320–324.
61. Sarathy MP, Madhavan P, Oomen M. Modified medial displacement and valgus osteotomy for unstable intertrochanteric fractures. Injury. 1997;28:601–605.
62. Stark A, Brostrom L, Barrios C, et al. A prospective randomized study of the use of sliding hip screws and Ender nails for trochanteric fractures of the femur. Int Orthop. 1992;16:359–362.
63. Steinberg GG, Desai SS, Kornwitz N, et al. The intertrochanteric hip fracture: A retrospective analysis. Orthopedics. 1988;11:265–273.
64. Swiontkowski MF, Harrington RM, Keller TS, et al. Torsion and bending analysis of internal fixation techniques for femoral neck fractures: The role of implant design and bone density. J Orthop Res. 1987;5:433–444.
65. Thomas AP. Dynamic hip screws that fail. Injury. 1991;22:45–46.
66. Tigani D, Laus M, Bettelli G, et al. The Gamma nail, sliding-compression plate: A comparison between the long-term results obtained in two similar series. Chir Organi Mov. 1992;77:151–158.
67. von der Heyde DA, Pommer A. Therapeutic possibilities in trochanteric fractures: Safe-fast-stable. Orthopade. 2000;29:294–301.
68. Walsh ME, Wilkinson R, Stother IG. Biomechanical stability of four-part intertrochanteric fractures in cadaveric femurs fixed with a sliding screw-plate. Injury. 1990;21:89–92.
69. Wellin DE, Galloni L, Gelb RI. Ipsilateral intertrochanteric and diaphyseal femoral fractures: Four patients treated by one technique. Clin Orthop. 1984;183:71–75.
70. Wolfgang GL, Bryant MH, O’Neill JP. Treatment of intertrochanteric fracture of the femur using sliding screw plate fixation. Clin Orthop. 1982;163:148–158.
71. Wu CC, Shih CH, Lee MY, et al. Biomechanical analysis of location of lag screw of a dynamic hip screw in treatment of unstable intertrochanteric fracture. J Trauma. 1996;41:699–702.
72. Yian E, Banerji I, Matthews L. Optimal side plate fixation for unstable intertrochanteric hip fractures. J Orthop Trauma. 1997;11:254–259.
73. Yoshimine F, Latta LL, Milne EL. Sliding characteristics of compression hip screws in the intertrochanteric fracture: A clinical study. J Orthop Trauma. 1993;7:348–353.
74. Zukor D, Miller B, Hadjipavlou A, et al. Hip pinning, past and present: Richards’ compression-screw fixation versus Ender’s nailing. Can J Surg. 1985;28:391–395.
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