Rigid Nail Research Articles

Surgical Treatment of Pediatric Femoral Shaft Fractures

Summary: Closed reduction and treatment by immediate spica cast is the preferred method of treatment of femoral shaft fractures in children as old as 4 years of age. Elastic stable intramedullary nailing has proven to be the most advantageous procedure in children between 4 and 14 years of age. Traction methods have a long hospital stay, discomfort, and the risk of overgrowth and malalignment. Plate fixation requires extensive dissection and produces a large scar. Rigid nailing is associated with a small but troublesome risk of avascular head necrosis and valgus deformity as a result of growth plate arrest. External fixation is the preferred method for the rare open and comminuted fractures. Elastic intramedullary fixation with elastic stable intramedullary nailing and Ender nails has a short learning curve for surgeons and a low complication rate. Short hospital stays and low costs of the implants are further advantages. Overgrowth in late controls is lower than that in other types of treatment, with an average of 5 mm.

(i) Femoral shaft fractures: North American and European perspectives

Femoral fractures are the commonest fracture of the lower extremity in children. The aim of treatment is to restore the child to normal function as quickly and effectively as possible. Problems with all treatments include malunion, stiffness and refracture. Intramedullary nails have additional problems with avascular necrosis of the femoral head and arrest of the greater trochanter apophysis. Traditional methods of casting and traction may cause pressure sores and pin site infection is common with external fixatiors. Treatment of these fractures in the UK has usually been traction and late casting in a skeletally immature child. In continental Europe, the use of flexible intramedullary nails is more common. In North America, treatment is based on the age of the child. Under the age of 10 years, an early hip spica is used. Flexible intramedullary nails are used for children over 10 years of age and rigid nails for skeletally mature children. The final decision depends on patient, family and surgeon preference plus the availability of resources.

Management of nail-bed fracture-lacerations using a tension-band suture

Nail-bed lacerations are frequently encountered in the emergency room and, along with other fingertip injuries, constitute the most common type of hand injury. 1 Among the various mechanisms of injury, trapping the finger in a closing door is the most common, 2 accounting for 25% of these injuries. 3,4 The rigid nail plate itself remains intact but gets separated from the underlying proximal nail bed to a variable extent and may come to lie on the dorsum of the proximal nail fold. In approximately 50% of cases, the underlying distal phalanx is fractured, 5 resulting in a transverse laceration of the nail bed, which is displaced with the osseous fragments. In extreme instances, the fingertip is partially amputated, remaining attached by only a narrow bridge of palmar soft tissues. Adequate primary treatment is necessary to minimize subsequent nail deformity. 6 The recommended management of these injuries is reduction of the fracture followed by repair of the nail bed. The nail plate is replaced and the fracture is stabilized with Kirschner wires (K-wires). 7,8 I describe here a technique for obtaining stability of the fracture in such injuries without the use of K-wire fixation, using a dorsal tension-band suture.

Locked intramedullary flexible osteosynthesis. A mechanical and clinical study of a new pin fixation device

We report the use of a new method of locked intramedullary flexible osteosynthesis (LIFO) in the treatment of 118 unstable fractures of the femur and tibia. The implant utilises a set of flexible pins with a separate locking device for their proximal ends. The LIFO system proved capable of stabilising unstable fractures, and most of the complications occurred during the early testing. At follow-up, 19 of 21 femoral fractures had healed; one become infected and one showed defective callus. Of the 78 tibial shaft fractures, five failed to consolidate and five had inadequate callus. Reaming of the tibial medullary canal was never necessary. Of 28 open fractures only one became infected. The system was most difficult to use in comminuted distal fractures of the tibia, with five failures of healing in 19 cases; these cases require considerable technical proficiency. The flexibility of the system appears to promote earlier consolidation of open fractures, and normal consolidation times for fractures with interfragmentary gaps of up to 10 to 12 mm. A comparative study of callus density in tibial fractures showed a mean improvement of 50 days in cases treated by the LIFO system compared with similar cases treated by rigid nailing.

Intramedullary Nailing of the Tibial Shaft Fracture: Comparison between Rigid and Flexible Nails

Intramedullary Nailing of the Tibial Shaft Fracture: Comparison between Rigid and Flexible Nails

Different healing patterns of experimental osteotomies treated by intramedullary nailing.

The healing of 52 diaphyseal osteotomies in rabbit tibiae was followed up histologically from 3 to 24 weeks after rigid intramedullary nailing. The histological evaluation was made from longitudinal sections through the osteotomy area. Particular attention was paid to the fracture healing pattern. A bulky periosteal response was visible in every specimen. At 24 weeks, the external callus was always well remodeled. The osteotomy line rapidly filled with bone from 6 weeks onwards. At 24 weeks, the site of osteotomy was detectable only on the basis of slight irregularity in the cortex. The secondary gap healing seen in 19 specimens was the most common type of bone union from 6 weeks onwards. In 13 specimens, the exact type of osteonal healing was not definable, since a solid union with good cortical reconstruction was always the final outcome. Altogether, four nonunions were detected throughout the study, none of these, however, in the specimens at 24 weeks. Considerable endosteal resorption was detected at 24 weeks, at which time at least one third of the original cortex had disappeared in all specimens. The rigid nail seems to ensure a relatively uneventful healing of the experimental osteotomies. Vast endosteal resorption and some nonunions make the use of medullary reaming in this connection doubtful.

Biomechanics of Rigid Tibial Nail Insertion Sites

The use of a very proximal insertion site for rigid intramedullary nailing was evaluated in a biomechanical study. The purpose of this study was to compare the bursting strains generated in a proximal tibia fracture fragment during rigid nailing, using the recommended insertion sites versus a more proximal site just anterior to the tibial plateau in the midline. Proximal one-third tibia fractures were created in 12 pairs of fresh cadaver specimens. Strain gauges were applied to the medial and lateral cortices of the proximal fragments. Lottes nails, Grosse-Kempf nails, and unreamed Russell-Taylor nails were inserted in four successive pairs of specimens. In each pair, one side used the recommended starting point, and the other side used the proximal insertion site. The strain was recorded at successive 2- to 4-cm depth intervals during nail insertion. In the Lottes group, much larger bursting strains were generated in the lateral cortex when using a distal starting point (P < 0.05). In the unreamed Russell-Taylor group, the anteromedial surface strains were significantly increased using a distal starting point (P < 0.05). The Grosse-Kempf group showed no significant difference in strains associated with any insertion point during tibial intramedullary nailing.

Controlled bending instability in the healing of diaphyseal osteotomies in the rat femur.

Ninety-six rats underwent a midshaft transverse osteotomy followed by osteosynthesis with an intramedullary nail, so that the effect of bending instability on time to union and on the mechanical properties of experimental diaphyseal fracture could be evaluated. Rotation was reduced by cementing both nail ends to the bone. Rigid nails made of stainless steel were used on one group and flexible nails made of polyacetal resin were used on another group. Serial radiographs were evaluated at 4-6-week intervals. Twelve animals with either nail type were killed at 4, 8, 16, and 24 weeks. Both femora were mechanically tested and the callus diameters were measured. There was no significant difference in time to union between the two groups. The cross-sectional area of callus was significantly higher at 8 and 16 weeks in femora with flexible nails. The strength, toughness, and resilience of the bone increased in this group until 24 weeks. Between 16 and 24 weeks, these parameters did not improve in femora with rigid nails. Poorer mechanical properties in femora with steel nails are interpreted as an effect of stress protection of the bone. This study, therefore, indicates that flexible nails prevent stress protection effects without delaying union.

An Investigation On The Behaviour Of Timber-Concrete Composite T-Beams

This paper describes a preliminary investigarion as the first part of a research programme being conducted at UTM on the subject of timber-concrete composite structural members. The purpose of this preliminary test was to establish the effectiveness of various types of shear connectors. The types of shear connectors investigated were nails, iron pipes and steel studs. It was found that steel studs were the most rigid connectors and nails were the weakest.The test results indicmed that composite construction of timber-concrete has potential to be applied in Malaysia, especially for the construction of houses and rural bridges.

Biomechanical Effects of Intramedullary Reaming and Nailing on Intact Femora in Rats

In order to study the effects of intramedullary reaming and nailing on bone mechanics, the left femur of male Wistar rats was reamed after circular periosteal stripping of the middle part as if for osteotomy. Osteotomy was, however, not performed. The rats were allocated into three groups: the first group had no nailing, the second group received flexible intramedullary polyacetal nails, and the third group was nailed with solid stainless-steel nails. Ten animals from the first group were sacrificed on the day of surgery. At four, eight, 16, and 24 weeks after operation, ten animals from each of the three groups were sacrificed. Both femora were tested mechanically and examined histologically. Intramedullary reaming resulted in the following immediate reductions in mechanical properties compared to the unoperated right femur: strength, 15%; stiffness, 20%; toughness, 7%; and resilience, 15%. From four weeks on, strength and energy absorption values were always lowest in the group with steel nails. The differences between groups were significant at four, 16, and 24 weeks. The lower values for mechanical properties of the femora with steel nails is interpreted as a result of stress shielding by the rigid nails. Flexible nails did not interfere with the ultimate restoration of mechanical properties of bones initially weakened by reaming.

Fracture healing after rigid intramedullary nailing in rats.

Rigid intramedullary nailing of the right tibia after osteotomy with resection of the fibula was performed on 48 male Wistar rats weighting 300-400 g. Nailing was performed with 1.4-mm nails after reaming. Nail stiffness was similar to that of intact tibias. The left leg remained unoperated as control. The animals were sacrificed after 4, 8, 12 or 16 weeks, and both tibiae were tested in a 3-point bending test. Of the 35 animals with the nail in situ, nine animals showed non-union at the time of testing. At 8 weeks stiffness had reached normal values, while strength and deflection showed about half of normal values. Poor strength and small deflectability combined with near normal stiffness may be taken as evidence that Wolf's law is valid also in newly formed tissues of fracture healing; the protection given by a rigid nail makes normal strength and pliability unnecessary.

Penetration in trochanteric fractures of the femur treated with rigid nail plates

One hundred and twelve trochanteric fractures have been analysed. A Jewett nail-plate was used in 81 patients and a Thornton nail-McLaughlin plate in 31. Penetration of the nail into or through the hip joint was the only complication studied in detail. It occurred in 41 cases: 31 (38 per cent) with the Jewett nails and 10 (33 per cent) in the other group. Both groups are comparable in that the nail-plate acts as a single rigid unit and the nail/plate angle varied, but the overall incidence of migration of the nail was similar. All the 112 cases were reviewed as one group. Penetration was more common in comminuted unstable types of fracture, in those poorly fixed, and in the older patients. Sixteen (14 per cent) well-fixed fractures showed penetration. It appears that one important additional reason for penetration in this series was the rigidity of the device and the poor quality of the bone. The incidence of nail penetration in comminuted unstable fractures of the femur might be reduced by using methods of fixation other than rigid nail-plates.

Effect of instability of experimental fracture healing.

Bilateral tibial osteotomy with fracturing of the fibula was performed on ten Wistar rats weighing 300--350 g. Intramedullary nailing was performed with 1.4 mm nails after reaming. On the left side solid stainless rods were used, while on the right side the nails had a middle part made of titanium-nickel wire covered with polyvinylchloride (PVC), giving the nail a high degree of flexibility. After 8 weeks, nine of the ten flexible nails showed fracture of the central wire. The continuity was, however, maintained by the PVC tube. The bones with flexible nailing always showed hypertrophic callus while there was only scanty callus on the side with rigid nailing. Strength, deformation at fracture and stiffness were measured in a three-point bending test after removal of the solid nails and the fibulae. The strength of the tibiae was greatest on the side with flexible nailing, as was the deformation at fracture. The mean stiffness was higher in the bones with rigid nails, but the difference here was not statistically discernible.