Fixation of osteotomies using bioabsorbable screws in the canine femur

The purpose of this study was to compare the healing properties of femoral osteotomies fixed by bioabsorbable screws (20:80 polyglycolic copolylactic acid copolymer) to standard stainless steel screws of a similar design in a dog femoral model. Two osteotomies were used, the trephine osteotomy (10 mm diameter) in the metaphyseal lateral femoral condyle and in the femoral diaphysis, and a unilateral osteotomy in the lateral femoral condyle. Two months after the trephine osteotomies, the femurs that contained the polymer screws were not significantly different in mechanical strength from the femurs treated with the stainless steel screws, either in the diaphyseal or metaphyseal model. There was no histological difference in bone healing between the metallic and polymer screws for all periods (2, 9, and 17 months). There was no adverse inflammatory response to the polymeric or metallic screws. By month 17, the polymer screws were resorbed completely. All the diaphyseal screw tracks had healed with bone and areas of remodeling were evident in two specimens. For the femoral condyle osteotomy model at 2 months, the polymer screws were present and intact, and all osteotomies healed with no evidence of inflammation. By 9 months, only one specimen had polymeric material left in the screw track. At 15 months, the screw tracks still were present but no evidence of any polymer remained. The tracks were filled with fibrous and adipose connective tissue. All osteotomies stabilized with either bioabsorbable polymer screws or stainless steel screws did heal satisfactorily without any complications, inflammation, or osteolysis. The polyglycolic polylactic acid copolymer may have a clinical role as a bioabsorbable material without the concerns for the osteolysis, foreign body reaction, and sterile abscess formation that have occurred with bioabsorbable fixation methods in the past.     

A method for open reduction and internal fixation of the unstable posterior sternoclavicular joint dislocation

Posterior sternoclavicular joint (SCJ) dislocations are most often stable after reduction but may be associated with significant complications related to the location of the medial head of the clavicle within the mediastinum. In rare instances, a posterior SCJ dislocation is irreducible or redislocates after a closed reduction. Because of the potential hazards related to compression of vital structures within the superior mediastinum, open reduction and internal fixation is usually required. Although open reduction is widely accepted as the method of choice, the best method for achieving stable fixation remains unanswered. We present the case of an unstable SCJ stabilized, in anatomic position, with two large-bore cannulated screws in conjunction with open reduction. We believe that the risk of hardware migration reported with the use of pins and wires and its catastrophic complications are greatly minimized using our technique.     

The Kalish osteotomy. A review and retrospective analysis of 265 cases

One hundred seventy-two patients (265 feet) were reviewed following correction of hallux abducto valgus surgery, using the Kalish modification of the Austin bunionectomy. Fifty-three cases were followed up on an average of 2.5 years from 1986 through 1992. The statistical results support the use of this osteotomy with rigid internal fixation for the reduction of the intermetatarsal angle, hallux abductus angle, and tibial sesamoid position. Patients are weightbearing immediately and are usually back in soft shoes or sneakers 2 weeks after surgery. Surgical techniques and complications of this procedure are discussed to help surgeons use this procedure in correcting hallux abducto valgus deformities.     

Porous-coated acetabular components with screw fixation. Five to ten-year results

The results of 136 consecutive primary total hip arthroplasties performed by one surgeon with the Harris-Galante-I porous-coated acetabular component were reviewed at a mean of seven years (range, five to ten years). In all hips, the outer diameter of the acetabular component was the same as the diameter of the final reamer used in the preparation of the acetabulum. However, this reamer was used only briefly at the rim of the acetabulum, and therefore the components had so-called press-fit stability. A mean of four screws (range, three to six screws) were used for additional fixation of the component. The clinical evaluation was performed with use of the Harris hip score. Standardized anteroposterior radiographs of the pelvis were assessed for migration of the component, radiolucent and radiodense lines, linear wear of the polyethylene, and osteolysis. No acetabular component had been revised for loosening and none were radiographically loose at the time of the most recent follow-up evaluation. There were no complications related to the use of the screws, and no screw had bent or broken. A non-progressive radiolucent line was seen in one acetabular zone in thirty-four hips (25 per cent) and in two acetabular zones in six hips (4 per cent). No hip had a radiolucent line in all three acetabular zones. The mean rate of linear wear of the polyethylene was 0.1 millimeter per year. There was no dissociation of the acetabular liner from the metal shell. Two hips (1 per cent) had asymptomatic osteolysis in the ischium and adjacent to the rim of the acetabular component; this was treated with grafting at the site of the lesion and exchange of the femoral head and the worn polyethylene liner. Five femoral components inserted without cement and one inserted with cement were revised because of loosening. The data suggest that, at a mean of seven years, fixation of this porous-coated component was uniformly excellent. The low prevalence of radiolucent lines and the absence of loosening are probably related, in part, to the technique of implantation. The low prevalence of polyethylene wear and pelvic osteolysis is a notable improvement compared with the results of arthroplasty with other porous-coated acetabular components. Although the results of the present study are encouraging, longer follow-up is necessary to determine the prevalence of late loosening and osteolysis.     

Bioresorbable fracture fixation in orthopedics: a comprehensive review. Part II. Clinical studies

Bioresorbable materials overcome two major disadvantages of the metal alloys most commonly used in fracture-fixation devices: their extreme stiffness, which causes stress shielding of the underlying bone, and the necessity, in a significant number of cases, of removing metallic implants after fracture healing is complete. The orthopedic surgeon now has the use of polylactic acid, polyglycolic acid, and polydioxanone implants for the fixation of small cancellous bone fractures. The currently available bioresorbable materials lack strength and stiffness and are associated with inflammatory reactions and osteolysis in a significant number of cases. Surgeons should use the available pins and screws with extreme care and attention to the characteristics of each individual injury, particularly its healing characteristics, as well as to the material's initial mechanical properties, degradation rates, and associated complications.     

Dynamic external fixation for distal radius fractures

Thirty adult patients with closed comminuted and mostly intraarticular fractures of the distal radius were treated by closed reduction and immobilization with a dynamic external wrist fixator during a 2-year period. In 13 patients with severely comminuted and unstable fractures, additional Kirschner wires were used. After 10 to 14 days of rigid fixation in neutral position, the motion element was unlocked to allow up to 30 degrees flexion. Six weeks later, the fixator was removed. The patients then were observed for an average of 24 weeks. An excellent functional outcome was seen in 6 patients (20%), a good outcome in 20 patients (67%), and a fair outcome in 4 patients (13%). Anatomically, 15 patients (50%) had an excellent result, 14 (47%) a good outcome, and 1 (3%) a fair outcome. Only minimal loss of reduction averaging 1 degree palmar tilt was seen during mobilization. There were 2 major complications: 1 deep Kirschner wire tract infection and 1 index metacarpal fracture. Minor complications such as sensory disturbances and pin tenderness were present but recovered completely after removal of the fixator. This study provides promising data and offers an alternative method in the treatment of distal radius fractures with severe comminution. In cases with postreductive unstable fragments, additional Kirschner wires should be used to allow early mobilization of the wrist.     

Enhanced fixation with hydroxyapatite coated pins

Three groups of seven patients had external fixation of middiaphyseal tibial fractures using uncoated pins, uncoated bicylindrical pins, and hydroxyapatite coated bicylindrical pins, respectively. All fractures were fixed with six pins, and all fractures united. Median pin insertion torque was 0.6, 1.2, and 1.3 Nm in the three groups, respectively. Median extraction torque was 0.1, 0.1, and 2.1 Nm, respectively. Both types of stainless steel pins showed a lower extraction torque than insertion torque in all cases, whereas the mean extraction torque in the hydroxyapatite coated pins was unchanged. Seven of the 14 patients receiving uncoated pins had pin tract infection, compared with none of the patients receiving hydroxyapatite coated pins. Hydroxyapatite coating of external fixation pins increases stability and thereby reduces the risk for pin tract infection and mechanical failure of fracture fixation.     

Loosening of Schanz screws in external fixator montage of the lower extremity

We analyzed the failure of Schanz pins in 234 patients with fractures of the lower extremity. All patients had the AO external fixator and stainless steel pins (ISO 58/32-1). The mean duration of treatment was 14 weeks. During this time 88 of a total of 1147 pins became loose. The first failures occurred 2 weeks after insertion. Most pins failed after 5-6 weeks. Early loosening was not accompanied signs of local infection, while late failures regularly developed pintract infections. Pins next to the fracture gap exhibited the highest rate of loosening. Intermediate pins had the lowest one. We could not detect an effect of the configuration of the external fixation. Eighty-one percent of the failed pins were exchanged consequently. We conclude that the early occurrence of pin loosening is due to mechanical reasons. Significant factors for this complications were the location close to the fracture gap and the number of pins in that segment.     

Hydroxyapatite coating of threaded pins enhances fixation

We measured the insertion and extraction torque forces in a randomised study of 76 external fixation screws in 19 patients treated by hemicallotasis for osteoarthritis of the medial side of the knee. The patients were randomised to have either standard tapered screws (Orthofix 6/5 mm) or the same screws with hydroxyapatite (HA) coating. One patient had two standard and two HA-coated screws. All patients had an anterior external fixator (Orthofix T-garche), with two screws in the proximal tibial metaphysis parallel to and about 2 cm below the joint surface and two in the tibial diaphysis. The mean torque forces for insertion of the standard screws were 260 Ncm for the proximal to medial screw, 208 for the proximal to lateral screw and 498 and 546 Ncm for the diaphyseal pins. The corresponding forces for the HA-coated pins were not significantly different. The torque forces for the extraction of the standard pins were 2 Ncm for the proximal pins, 277 and 249 Ncm for the distal pins and 482, 478, 585 and 620 Ncm, respectively (p < 0.005) for the HA-coated pins. All 18 of the metaphyseal standard screws were loose at extraction (extraction force < 20 Ncm), but only one of the HA screws in the metaphysis was loose. In the diaphysis the standard screws lost about 40% of their fixation in contrast to the HA-coated screws which retained full fixation strength.     

The nonfixated Austin bunionectomy: a retrospective study of one-hundred procedures

A retrospective evaluation of 64 randomly selected patients with 100 nonfixated Austin bunionectomy procedures was performed. A radiographic and a clinical evaluation were performed, including an analysis of preoperative and postoperative angles as well as postoperative complications. This study demonstrates a similar complication rate for nonfixated Austin bunionectomies as compared with previous studies with internal fixation. Removal of the fibular sesamoid was performed in 90% of the cases and did not increase the incidence of hallux varus. The nonfixated Austin bunionectomy is an acceptable alternative to the correction of hallux valgus. If internal fixation is utilized, the most cost-effective device should be used.     

The treatment of symptomatic os acromiale

During a four-year period, fourteen individuals (fifteen shoulders) who had been seen at the shoulder service of our institution because of pain in the shoulder had a radiographic finding of an os acromiale. On clinical examination, the pain appeared to be due to an unstable os acromiale because the patients had point tenderness over the acromion and pain on forward elevation of the shoulder. The diagnosis of an os acromiale was confirmed on radiographs, magnetic resonance images, or a bone scan. Eight patients had an associated tear of the rotator cuff. The os acromiale was located in the pre-acromion in one shoulder, the meso-acromion in eleven shoulders, and the meta-acromion in three shoulders. At the operation, the anterior aspect of the acromion was found to be unstable in all shoulders. Eleven patients (twelve shoulders) had open reduction of the os acromiale and insertion of an autogenous iliac-crest bone graft. Of those patients, four (five shoulders) had open reduction and internal fixation with a tension-band procedure with use of pins and wires. Only one of those shoulders had a solid osseous union, and the other four shoulders had a non-union that was due to a disruption of the fixation. The remaining seven patients (seven shoulders) had open reduction and internal fixation with use of cannulated screws and a tension-band construct; a solid osseous union was achieved in all but one of them. One patient had excision of the pre-acromion, which relieved the pain. Two patients who had had failed open reduction and internal fixation had excision of a grossly unstable os acromiale in the meso-acromion; both patients had pain and weakness after this procedure. Of the twelve shoulders that had open reduction and bone-grafting, seven had union of the os acromiale; the average time to radiographic and clinical union was nine weeks (range, seven to twenty weeks). We concluded that, although it is rare, symptomatic unstable os acromiale does occur and can be effectively treated with use of autogenous bone-grafting and internal fixation with a rigid tension-band construct and cannulated screws.     

Bioabsorbable rods and pins for fixation of metacarpophalangeal arthrodesis of the thumb

We report results on the use of bioabsorbable pins and intramedullary rods made of high-molecular-weight polylactic acid in both experimental and clinical conditions. In the experimental study, bioabsorbable rods were implanted in rabbit femora. Histologic assessment on nondecalcified bone showed that resorption of the material began at 4 months after implantation and gradually fragmented over a period of 3 years. In 12 patients 13 metacarpophalangeal joints of the thumb were arthrodesed by using one bioabsorbable intramedullary rod with one or two oblique pins. All joints fused within 6 to 8 weeks. During that period there was no sign of inflammation, and there were no nonunions. Postoperative magnetic resonance imaging assessment was done in all rabbits and eight patients. This modality is a useful tool in postoperative evaluation of the position and shape of the rod but is not sufficiently sensitive to assess the presence of local inflammation and the rate of resorption of the rods.     

Pacemaker mode selection and survival: a plea to apply the principles of evidence based medicine to cardiac pacing practice

Impingement syndrome is usually caused by encroachment on the rotator cuff of the acromion, coracoacromial ligament, acromioclavicular joint or coracoid process. Bursal causes of impingement are rare but include rheumatoid thickening, and thickening from previous and iatrogenic causes such as sutures, pins, or wires left from previous surgery. We report a case of synovial osteochondromatosis presenting as chronic impingement syndrome. Synovial osteochondromatosis may be difficult to differentiate from chronic calcific tendinitis, but we describe a radiological sign and its anatomical basis that can differentiate between the two. If densities are seen on plain radiographs distal to the greater tuberosity, then loose bodies within the subacromial bursa should be considered.     

Open reduction and internal fixation of forearm fractures in children

We retrospectively reviewed 16 children younger than 13 years with 17 fractures of the shafts of the radius or ulna or both who had undergone an open reduction-internal fixation (ORIF). ORIF was performed when a closed reduction was deemed unacceptable in 14 radius fractures and for three unstable open fractures of the radius. The average age was 9.4 +/- 2.3 years (range, 5.0-12.5). Of the 14 fractures with an unacceptable closed reduction, soft-tissue interposition was encountered in seven. Fixation was secured by plates and screws, percutaneous Steinmann pins, or intramedullary Steinmann pins. There were no delayed unions or nonunions, no infections, and no neurovascular injuries. The average follow-up was 12.3 months; all 17 fractures had excellent results (forearm rotation loss of < 10 degrees). Our study indicates that excellent results can be expected with no increased risk of complications if the treating physician elects to proceed with an ORIF in a pediatric forearm fracture with proper indications.     

Correlation between the prevalence of certain fungi and sick building syndrome

We retrospectively reviewed the results of using a biplanar chevron osteotomy performed on patients who presented with hallux valgus deformities with an increased distal metatarsal articular angle (DMAA). The study included 17 feet (14 patients) of 12 women and 2 men. The average follow-up was 33 months. The average American Orthopaedic Foot and Ankle Society Hallux Metatarsophalangeal-Interphalangeal Clinical Rating Score was 91. Ten of the 14 patients (13 of 17 feet) stated that they would choose to undergo the procedure again. The hallux valgus angle was improved from an average of 22 degrees to 18 degrees, the intermetatarsal angle from 11 degrees to 9 degrees, and the DMAA from 16 degrees to 9 degrees. We have demonstrated this procedure to be useful in the treatment of symptomatic bunion deformities with an increased DMAA.     

Intrapartum fetal oxygen saturation monitoring in congenital fetal heart block

Precutaneous Kirschner wire fixation of displaced Gartlands types II and III supracondylar fractures with image guidance remains a preferred procedure for most orthopaedic units. Various K-wire configurations have been in use, but recent objective evaluation of pin stability has favoured two techniques; the 2 crossed pins placed from the medial and lateral epicondyles, and 2 parallel lateral pins when the former technique is impracticable because of swelling. We reviewed patients who had K-wire fixation precutaneously over a 2-year period (Feb 1996 to Feb 1998). There were 44 children, 30 males, 14 females, ages between 1-15 years. 19 patients had (medial and lateral pins) 15, (2 parallel lateral) and 10 patients (2 lateral crossed) precutaneous pin placement respectively. Their postoperative course indicated that maximum stability was obtained with two opposite crossed pins, followed by the 2 paralleled pin method. These observation determined the choice of technique by the surgeons who operated on these patients.     

Kirschner wire placement in the emergency room. Is there a risk?

To evaluate the safety of inserting Kirschner wires into bones or across joints in a setting other than a completely sterile operating theatre, a prospective study of all hand fractures treated by closed reduction and internal fixation was conducted in a mid-city Emergency Department. Indications for percutaneous fixation were displaced, unstable long bone fractures of the hand. 71 fractures in 68 patients were treated, and in 91% the fixation crossed a joint. No patient developed osteomyelitis or pyarthrosis, and there was no deep pin track sepsis. Seven patients with open fractures healed without infection or delayed union. Patients in whom data were available obtained 90% to 95% of the motion of the contralateral digit. The taboo against percutaneous fixation of fractures in a non-operating theatre setting is not warranted. The procedure can be performed with minimal complications in an out-patient setting.     

Atraumatic osteolysis of the distal clavicle: MR findings

OBJECTIVE: The purpose of this study was to describe the MRI appearance in atraumatic osteolysis of the distal clavicle (AODC). MATERIALS AND METHODS: We retrospectively evaluated MRI, medical records, ancillary diagnostic imaging studies and clinical course in five men and two women (mean age, 39 years) in whom the final clinical diagnosis of AODC was established. None of the patients had significant shoulder injury, but all participated in activities involving repetitive strain of the acromioclavicular (AC) joint. In three of these patients, we performed follow-up MRI (ranging from 5 1/2 to 15 months after the initial MRI). RESULTS: In all seven patients, signal intensity changes within the intramedullary portion of the distal clavicle on MRI were consistent with diffuse bone marrow edema. Marrow edema was most conspicuous on STIR imaging and occasionally could be misinterpreted as normal marrow signal patterns on spin-echo imaging. Cortical thinning or irregularity of the distal clavicle was seen in six cases and tiny subchondral cysts were seen in three, corresponding to subtle cystic changes on shoulder radiography. Limited bone scans obtained in two patients showed markedly increased uptake of radiotracer at the distal clavicle and AC joint. Histologic examination in one case showed disruption of articular cartilage, subchondral cysts, and metaplastic bone formation with increased osteoclastic activity. Follow-up MRI in three patients who were asymptomatic following conservative therapy showed normalization of marrow signal intensity. CONCLUSION: Atraumatic osteolysis of the distal clavicle is a relatively uncommon but important cause of shoulder pain. Particularly when the clinical history is suggestive of repetitive AC joint stress, MRI of the distal clavicle should be examined closely for marrow edema, cortical irregularity, and cystic changes. Such abnormalities may be especially conspicuous when STIR imaging techniques are used.     

Orthofix external fixation of distal radius fractures: complications associated with screw size

We did a retrospective analysis of 28 patients who were treated with the Orthofix external fixation system for complex fractures of the distal radius to study complications associated with screw size. The 14 patients in group 1 had a 4.5/3.5-mm tapered screw placed in the metacarpal bone; the 14 patients in group 2 had a 3.5/3.3-mm tapered screw placed in the metacarpal bone. Both groups had 4.5/3.5-mm tapered screws placed in the radius. Two patients in group 1 had metacarpal pin tract infections; no patients in group 2 had a distal pin tract infection. Two patients in group 1 had a fracture of the metacarpal; only one patient in group 2 had a fracture of the metacarpal. In both groups two patients had proximal pin tract infections at the radius screw fixation site. There was no screw breakage in either group. The unique design of the tapered Orthofix screw allows it to be removed almost painlessly in the clinic. At installation in the operating room, however, the surgeon must remember not to back the threaded pin out for fine adjustment of bony penetration. Any reverse excursion of the threaded shaft will loosen the tapered screw and cause early failure of the fixation. We no longer use the 4.5/3.5-mm screw when managing wrist fractures with the Orthofix external fixation system. It is now our policy to use the 3.5/3.3-mm screw for fixation of the Orthofix external frame to both the metacarpal bone and the radius.     

Retrospective diagnostics of congenital cytomegalovirus infection performed by polymerase chain reaction in blood stored on filter paper

OBJECTIVE: External reference points, particularly Kirschner pins (K-wire), placed in the region of the nasion have been shown to improve the accuracy of maxillary vertical repositioning. Although no complications associated with this technique have been reported, there is a potential for injury to the anterior cranial fossa or frontal sinus. The purpose of this study was to measure the shortest distance from the nasion to the anterior cranial fossa and from the nasion to the frontal sinus. These measurements were used to establish anatomic guidelines governing safe placement of external reference point pins. STUDY DESIGN: Twenty-seven cadaver heads were sectioned in the midsagittal plane for gross study. Using a Boley gauge, two specific measures were obtained: (1) distance from deepest depression of nasion to the most anterior and inferior projection of the anterior cranial fossa, and (2) distance from nasion to the most inferior aspect of the frontal sinus. All measurements were made in the midsagittal plane. RESULTS: The average distance from nasion to anterior cranial fossa was 16.9 mm (range 13.0 to 20.0 mm) and the smallest distance, 13.0 mm, was seen in two specimens. The average distance from nasion to the frontal sinus was 6.2 mm (range 2.0 to 10.0 mm) and the smallest distance, 2.0 mm, was seen in three specimens. CONCLUSION: Based on our findings, we recommend the following: (1) place pin to a depth of no more than 8 mm into bone, (2) place pin 5 to 10 mm inferior to soft tissue nasion, and (3) place pin in an anterosuperior to posteroinferior direction (i.e., roughly perpendicular to the nasal dorsum). When these anatomic guidelines are followed, one would expect minimal morbidity associated with the placement of ERP pins.