Prevention of pin tract infection with iodine-supported titanium pins

Background

Pin tract infection is one of the most common complications of external fixation. We developed techniques to coat titanium implant surfaces with iodine. This study clinically evaluated the infection-preventive effects and biological safety of iodine-coated external fixation pins.

Patients and methods

Iodine-supported pins were placed in 39 limbs of 38 patients. The mean age of the patients was 33.6 years. Twenty-six patients were men and 12 were women. In all patients, the iodine-coated pins were used to prevent infection. There were 476 pin insertion sites. Pin sites were classified according to the Checketts–Otterburn classification (grade 1–6). White blood cells (WBC) and C-reactive protein (CRP) were measured pre- and postoperatively in all patients. To confirm whether iodine from the implant affected physiological functions, thyroid hormone levels in the blood were monitored. The change in the amount of iodine deposited in the body over time was calculated by examining the removed pins.

Results

External fixation was used for a mean duration of 6 months. Grade 1 infection was found in 2.5 % of patients, and grade 2 infection in 1.1 %. There was no patient with an infection of grade 3 or higher. Median WBC levels were in the normal range, and median CRP levels returned to <0.3 mg/dl within 3 weeks after surgery. Abnormalities of thyroid gland function were not detected. The amount of iodine was maintained for a long time, with approximately 40 % remaining after 1 year.

Conclusions

Iodine-supported titanium pins were able to decrease the pin tract infection rate and had no impact on thyroid function. These results suggest that iodine-coated titanium pins are biologically safe and effective at preventing pin tract infections.     

Improvement of the bone-pin interface strength in osteoporotic bone with use of hydroxyapatite-coated tapered external-fixation pins. A prospective, randomized clinical study of wrist fractures

BACKGROUND: Achieving adequate fixation strength in osteoporotic bone is a challenge. In this study, we examined the use of hydroxyapatite-coated tapered external-fixation pins for the fixation of wrist fractures in patients with osteoporosis. METHODS: Twenty female patients with osteoporosis and a fracture of the wrist were divided into two paired groups and randomized to receive either standard tapered pins or hydroxyapatite-coated tapered pins. Two pins were inserted in the distal part of the radius, two pins were inserted in the second metacarpal, and an external fixation device was mounted. All fixation devices were removed six weeks after surgery. RESULTS: The mean pin-insertion torque (and standard deviation) was 461 +/- 254 Nmm in the group managed with standard pins and 332 +/- 176 Nmm in the group managed with hydroxyapatite-coated pins (p = 0.01). The mean pin-extraction torque was 191 +/- 155 Nmm in the group managed with standard pins and 600 +/- 214 Nmm in the group managed with hydroxyapatite-coated pins (p < 0.0001, power 95%). The mean extraction torque was lower than the corresponding insertion torque at each pin position in the group managed with standard pins (p < 0.05), whereas the mean extraction torque was higher than the corresponding insertion torque at each pin position in the group managed with hydroxyapatite-coated pins (p = 0.001). Two patients managed with standard pins and no patient managed with hydroxyapatite-coated pins had a pin-track infection. Pain during pin removal did not differ between the two groups. CONCLUSIONS: The present study showed that hydroxyapatite-coated tapered external-fixation pins provided improved fixation in the treatment of wrist fractures in patients with osteoporosis.     

The influence of hydroxyapatite coating of external fixator pins on pin loosening and pin track infection: A systematic review

Objective

The primary objective of this systematic review of published randomised controlled trials was to evaluate whether there was a clinical benefit in terms of pin loosening and pin track infection, or deep infection, associated with hydroxyapatite coating of external fixator pins. The secondary objective was to evaluate whether there was a clinical benefit in terms of loss of alignment or malunion associated with hydroxyapatite coating of external fixator pins.

Methods

Studies included were identified by a PubMed search for relevant randomised controlled trials on the 20th of December 2007. A systematic review was performed.

Results

All of the studies concluded that there was significantly less pin loosening in the HA-coated groups although the definition of loosening was based on different criteria. However, there was insufficient evidence to properly evaluate the clinical benefit in terms of the numbers needed to treat to avoid premature pin removal. There was also insufficient evidence to evaluate whether any clinical benefit is gained by using HA-coated pins with respect to deep infection and malunion.

Conclusion

A well designed large randomised controlled trial is required to determine the numbers needed to treat with HA-coated pins to reduce the incidence of clinically relevant pin loosening, axial deformity and pin track or deep infection.     

Fixation of titanium and hydroxyapatite-coated implants in arthritic osteopenic bone.

Retrieval studies of porous-coated prostheses have demonstrated deficient bony ingrowth in high percentages. Possible reasons for this are lack of initial mechanical stability and the presence of osteopenia. The authors studied ingrowth of osteopenic bone into titanium alloy (Ti) porous-coated implants with and without hydroxyapatite (HA) coating in an experimental dog model. Unilateral osteopenia of the knee with a 20% reduced bone density as judged by computed tomography (CT) scanning (P less than .001) was induced in 12 mature dogs by weekly intraarticular injections of Carragheenin into the right knee for 12 weeks, with the left knee serving as control. Ti porous-coated cylinders were inserted in press-fit bilaterally in the lateral femoral condyles in six dogs. HA-coated titanium plugs were implanted similarly in another sex-, age-, and weight-matched group of six dogs. Bony ingrowth after 4 weeks was significantly reduced for Ti implants in osteopenic bone compared to control bone, but HA-coated implants were covered by equal amounts of bone tissue. Bone-implant shear strength of Ti implants also was reduced in osteopenic bone compared to control bone. In control bone, the anchorage of Ti implants was stronger than HA-coated implants, whereas the fixation of Ti and HA-coated implants was equal in the osteopenic bone. The results demonstrate that the bony fixation of Ti porous-coated implants is weakened by the presence of experimentally induced osteopenia. However, the fixation of HA-coated implants was not affected by the osteopenic condition in the surrounding bone. The fixation of Ti and HA-coated implants was equal in osteopenic bone, whereas the fixation of Ti porous-coated implants was superior to that of HA-coated implants in control bone.     

Antimicrobial efficacy of external fixator pins coated with a lipid stabilized hydroxyapatite/chlorhexidine complex to prevent pin tract infection in a goat model.

BACKGROUND: Pin tract infection is a common complication of external fixation. An antiinfective external fixator pin might help to reduce the incidence of pin tract infection and improve pin fixation. METHODS: Stainless steel and titanium external fixator pins, with and without a lipid stabilized hydroxyapatite/chlorhexidine coating, were evaluated in a goat model. Two pins contaminated with an identifiable Staphylococcus aureus strain were inserted into each tibia of 12 goats. The pin sites were examined daily. On day 14, the animals were killed, and the pin tips cultured. Insertion and extraction torques were measured. RESULTS: Infection developed in 100% of uncoated pins, whereas coated pins demonstrated 4.2% infected, 12.5% colonized, and the remainder, 83.3%, had no growth (p < 0.01). Pin coating decreased the percent loss of fixation torque over uncoated pins (p = 0.04). CONCLUSION: These results demonstrate that the lipid stabilized hydroxyapatite/chlorhexidine coating was successful in decreasing infection and improving fixation of external fixator pins.     

Hydroxyapatite-coated external-fixation pins. The effect on pin loosening and pin-track infection in leg lengthening for short stature

Pin loosening and infection are inherent complications of external fixation. This study deals with their effects of using either hydroxyapatite (HA)-coated or uncoated external fixation pins in leg-lengthening procedures on patients of short stature. We used HA-coated pins on one side and uncoated pins on the other (randomly determined) in 28 bilateral lengthenings undertaken in 23 patients. A total of 322 pins was used. The mean implantation time was 530 days and the mean lengthening achieved was 78% of initial bone length. Mean extraction torque was 7611.6 Nmm degree(-1) for HA-coated and 85.4 Nmm degree(-1) for uncoated pins (p < 0.001). The rate of pin loosening was 4% (7/161) for HA-coated and 80% (129/161) for uncoated pins (p < 0.001). There was no statistically significant difference in the incidence of pin-track infection between the two groups. The use of HA coating appears to be an effective method of reducing the incidence of pin loosening in external fixation with a long implantation time and for mechanically highly stressed procedures such as leg lengthening for short stature.     

螺纹外露对外固定架钉道感染的影响

目的 观察螺纹外露对外固定钉道感染的影响。方法 回顾性分析2003年12月至2017年1月我院骨科收治的332例胫腓骨开放性骨折病人的临床资料,均采用单边外固定架临时固定。其中男220例,女112例;左侧177例,右侧155例;年龄为（33.4±2.6）岁（27~51岁）。按Gustilo分型：Ⅱ型79例,Ⅲ型253例。外固定架固定时间为（76.3±9.2） d（66~93 d）。按螺纹是否外露,分为皮外组与皮内组,其中皮外组164例,皮内组168例。取出Schanz螺钉时,采集钉道浅表和深部的分泌物样本,并送细菌培养。记录钉道愈合情况、浅表和深部细菌培养结果及其类型。结果 皮内组钉道愈合等级（甲级：66例;乙级：99例;丙级：3例）优于皮外组（甲级：50例;乙级：90例;丙级：24例）,差异有统计学意义（χ²=19.456,P=0.001）。皮外组浅表感染96例,皮内组浅表感染101例,差异无统计学意义（χ²=0.086,P=0.769）。皮外组深部感染21例,皮内组2例,两组比较差异有统计学意义（χ²=17.362,P=0.001）。皮外组与皮内组钉道感染均以金黄色葡萄球菌为主要菌种,两组间的细菌构成比比较,差异无统计学意义（Z=-0.135,P＞0.05）。结论 螺纹外露会增加单边外固定深部感染概率,应尽量将螺纹置入皮下或选择短螺纹螺钉。     

Fixation of the Austin osteotomy with bioresorbable pins

Clinical trials were conducted at the Foot Clinics of New York, testing the use of the Johnson & Johnson Orthosorb absorbable pins as an integral absorbable form of fixation of the Austin osteotomy. Two Orthosorb pins were inserted across the osteotomy from dorsal to plantar. Patients were placed in a plaster splint and allowed to walk with weightbearing as tolerated within 2 weeks of the procedure. A protocol was designed to include a 6-month follow-up with regularly scheduled postoperative examinations. These examinations included a review of pain, walking ability, edema, and measurements of dorsiflexion and plantarflexion. No complications have occurred in this patient population. This study has shown that for a selected group of surgical candidates, Orthosorb bioresorbable pins are an effective form of fixation for the Austin osteotomy.     

Clinical benefit of hydroxyapatite-coated pins compared with stainless steel pins in external fixation at the wrist: A randomised prospective study

Background

The purpose of this study was to determine the clinical benefit of hydroxyapatite (HA)-coated pins compared with standard stainless steel pins in external fixators applied for unstable fractures of the distal radius.

Methods

A total of 40 patients (160 pins) with unstable wrist fractures were randomised for uniplanar fixator treatment with the use of identically designed, commercially available pins either composed of stainless steel (steel group) (n = 20) or coated by hydroxyapatite (HA group) (n = 20). Each pin site was clinically evaluated concerning erythema and grade of drainage as well as pain intensity (numeric rating scale (NRS) 0-10) and, additionally, radiological assessment was performed concerning pin-loosening/infection as well as fracture healing at T1 (Ø18 days), T2 (Ø44 days) and T3 (Ø65 days). In case of pin-track complication, the patient was followed continuously. The need for intensified pin-site care, oral or intravenous antibiotic medication, re-admission for additional surgery and premature fixator removal was documented. Bone mineral density (BMD) was determined by dual energy X-ray absorptiometry. At fixator removal (T2), the pin-extraction strength was measured by the use of an electronic torque wrench.

Results

Two pin-track infections requiring daily pin-site care and oral antibiotics occurred in the HA group (2.6%) compared with four in the steel group (5.3%) (p = 0.601) and although a trend towards a superior performance of HA pins was detectable, the majority of clinical pin-site-parameters were comparable in both groups. At the end of the fixator therapy, the HA group showed a non-significant lower rate of loose pins (n_{steel group} = 9; n_{HA group} = 6; p = 0.864) and both hydroxyapatite-coated pins showed at the radius a significantly stronger pin-bone bonding measured by the torque wrench (p_{proximal radius pin} = 0.007; p_{distal radius pin} = 0.031). Except for elderly patients of the steel group (p = 0.018), all demographic-, health- and injury-related data including BMD were not correlated to any type of pin-site complication in both groups (p > 0.05). Since all fracture healed uneventfully without any type of additional surgery, the number of patients suffering clinically relevant pin-related complications showed no significant difference between both groups (p = 0.707).

Conclusions

The use of HA-coated pins compared with standard stainless-steel pins in external fixation for unstable wrist fractures yields only a trend towards a superior clinical outcome.     

Fixation of subcapital femoral osteotomies by poly-L-lactic acid pins

Summary In an experimental study in nine sheep, self-reinforced poly-L-lactic pins were used to fix subcapital femoral osteotomies. One out of three was consolidated at 3 weeks. At 6 weeks, one out of 3 had failed, and the other two were united by bone. At 12 weeks all the osteotomies had healed. These results showed that absorbable SR-PLLA pins could be used to fix this type of osteotomy.

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Résumé On a utilisé dans une étude expérimentale portant sur neuf moutons adultes des broches résorbables de poly-L-lactide (SR-PLLA) pour fixer des ostéotomies sous-capitales du fémur. Les examens radiographiques, microradiographiques et histologiques ont montré qu'à la troisième semaine l'ostéotomie était consolidée une fois sur trois, à la sixième semaine deux fois sur trois et à la douzième semaine dans tous les cas. Les résultats de cette étude montrent qu'il est possible d'utiliser des broches résorbables de SR-PLLA pour la fixation des ostéotomies fémorales sous-capitales, mais il semble nécessaire de réaliser des séries expérimentales plus importantes, en ayant recours à des implants améliorés.

     

Fixation of humeral surgical neck fracture using contoured pins versus straight pins: a mechanical study

The conventional procedure for displaced fracture of the surgical neck of the humerus uses straight pins inserted from the lateral aspect towards the head of the humerus. The objective of this study was to compare the mechanical properties of fixation by contoured (curved) pins to those fixed with regular straight pins. A transverse osteotomy was made in 30 fresh-frozen sheep humeri in the proximal metaphyseal bone region, and pins were inserted using either three parallel straight pins or three contoured pins in different planes. The assemblies were subjected to bending or rotational stresses at the fracture site. Loads versus deformations were acquired during loading and rigidity was calculated. Results showed that in bending, fixation with straight pins was 31% more rigid compared to contoured pins (p < 0.001), and in torsion, fixation using contoured pins was 21% more rigid compared to straight pins (p < 0.001). A combination of the two fixation types should be considered.     

Fixation of displaced subcapital femoral fractures. Compression screw fixation versus double divergent pins

One hundred and twenty-seven consecutive patients with displaced subcapital fractures of the femoral neck (Garden Grade III or IV) all under 80 years of age and independently mobile, were randomly allocated to fixation with either double divergent pins or a single sliding screw-plate device. The incidence of non-union and infection in the sliding screw-plate group was significantly higher, and we believe that when internal fixation is considered appropriate multiple pinning should be used. Mobility after treatment was disappointing in about half of the patients, and we feel that internal fixation can only be justified in patients who are physiologically well preserved and who maintain a high level of activity.     

Enhanced bone ingrowth and fixation strength with hydroxyapatite-coated porous implants

The effect of a hydroxyapatite (HA) coating on the interface attachment strength, rate of development of attachment strength, and degree of bone ingrowth of porous implants was investigated. Implants with ideal surgical fits and those having interface gap spaces were evaluated using femoral transcortical and intramedullary models. The application of a thin HA coating to porous implants significantly enhanced both interface attachment strength and bone ingrowth. The rate of development of interface strength and bone ingrowth was also more rapid with the HA-coated system. There was no evidence of any disruption, loss, or resorption of the HA coating.     

Fixation of femoral neck fractures. A four-flanged nail versus threaded pins in 200 cases

Two methods of internal fixation for cervical hip fractures were compared in a "randomized to surgeons" type of study. One hundred patients were treated with the Rydell four-flanged nail and 100 with the Gouffon pins. Redisplacement, nonunion, or segmental collapse occurred in 27 patients operated on with the Rydell nail and in 29 patients operated on with the Gouffon pins. According to the actuarial method of follow-up, the failure rates after 2 years were 31 and 33 percent in the two groups.     

Kirschner wire pin tract infection rates: a randomized controlled trial between percutaneous and buried wires

This prospective, randomized trial compares the infection rates of Kirschner wires left percutaneously and those buried deep to the skin in a group of patients with isolated distal radial fractures. Percutaneous wires had a significantly greater infection rate than wires which were buried deep to the skin.     

External fixation of the pelvic ring: An experimental study on the role of pin diameter,pin position,and parasymphyseal fixator pins

Background?The mechanical properties of current external fixator systems for unstable (type C) pelvic ring fractures are inferior to internal fixation, and are not optimal for definitive treatment. We explored methods to increase stability of external fixator constructs.

Methods?An experimental model was used for load tests. The same pelvic fixator was used while different pin diameters, pin positions, and modes of pubic symphysis fixation were tested.

Results?Changing of the pin diameter of the unthreaded part from 6 to 8?mm resulted in an increase in stiffness of 20%. An increase in stiffness by a factor of 1.9 was found by placing a pin on the iliac crest and one supra-acetabular. An additional increase by a factor of 3.6 was obtained by adding pubic symphysis plate fixation. Parasymphyseal pin fixation instead reduced stiffness, but not so much as when parasymphyseal pins were connected to the external fixator of the pelvic ring. The final configuration was at least 6 times stiffer than the initial configuration.

Interpretation?The new concept of parasymphyseal pin fixation connected to an external fixator of the pelvic ring produces a considerable increase in stability for the treatment of type C pelvic ring injuries, as does an increase in pin diameter and alternative pin positioning.