MRI follow-up after free tendon graft reconstruction of the thumb ulnar collateral ligament.

OBJECTIVE: Our aim was to analyse whether MRI is useful in the follow-up of reconstruction of the ulnar collateral ligament (UCL) of the metacarpophalangeal joint of the thumb, to describe normal postoperative findings, and to evaluate different MR sequences. MATERIAL AND METHODS: Our study material consists of 10 patients who, because of a chronic rupture of the ulnar collateral ligament of the thumb, had been operatively treated using a free tendon graft. The patients were, in addition to the clinical examination and radiographs, also imaged using MRI both pre- and postoperatively. The postoperative MRI controls, undertaken at 2, 12 and 24 months were analysed without knowledge of the clinical or radiographic findings. RESULTS: The reconstructed UCL was well visualised on MRI. One graft rupture was diagnosed on MRI and was later operatively confirmed. No increase in osteoarthritis of the metacarpophalangeal (MP) joint of the thumb was seen during the follow-up. The single most informative MR sequence was T2TSE in the coronal plane. CONCLUSION: Magnetic resonance imaging may provide a clinically valuable means of assessing graft integrity in patients with suspected postoperative graft failure after UCL reconstruction, although we do not consider MRI necessary in the routine follow-up of patients with an uneventful recovery.

Operative treatment of distal radius fractures.

The incidence of distal radius fractures is increasing together with the average age of population. Intra-articular incongruity is the most probable cause of unsatisfactory outcome of distal radius fractures in younger and more active patients. Thus, the main goal in the treatment of distal radius fractures should be restoration of articular congruence. A computed tomography (CT) is recommended to help surgeon in preoperative planning in the treatment of comminuted intra-articular fractures. New implants have been designed to provide stable enough fixation for early mobilisation after surgery and to lower rather high complication rates related to conventional fixation methods such as external fixation and dorsal plating. The most common complications related to volar fixed angle plating such as flexor and extensor tendon problems, median nerve neuropathy, and screw diplacement into the radiocarpal joint are surgeon related and are avoidable with proper education. More randomized prospective studies are needed to prove superiority of any fixation method to another.

Comparison of in vitro hydrolysis, subcutaneous and intramedullary implantation to evaluate the strength retention of absorbable osteosynthesis implants.

To evaluate the behaviour of mechanical properties of absorbable osteosynthesis implants in vivo, the strength retention of self-reinforced polyglycolide rods in distilled water at 37 degrees C in the subcutis and femoral medullary cavity of the rabbit was investigated. The self-reinforced polyglycolide rods lost their strength significantly faster in vivo than in vitro. The strength loss of the self-reinforced polyglycolide rods was only slightly faster in the medullary cavity than in the subcutis. As the removal of the implants from the medullary cavity became difficult 5-6 wk after implantation, it is suggested that subcutaneous implantation would be a suitable method to evaluate the strength retention of absorbable osteosynthesis implants.

Comparison of the fixation of subcapital femoral neck osteotomies with absorbable self-reinforced poly-L-lactide lag-screws or metallic screws in sheep.

Seven subcapital femoral osteotomies of adult sheep were each fixed with two absorbable self-reinforced poly-L-lactide lag-screws, and seven other osteotomies were each fixed with two metallic cancellous bone screws. At 3 and 12 weeks, radiographs were taken and callus formation, displacement, and union were evaluated. At 12 weeks, the animals were killed and strength measurements were carried out. According to the radiographs, union was achieved in six of seven osteotomies in both groups, while after 3 weeks one fixation in both the group treated with absorbable screws and the group treated with metallic screws had failed. There were no statistical differences between the groups with respect to callus formation or displacement. Regarding the strength of the osteotomized bones, at 12 weeks there were no statistically significant differences in the load-carrying capacity between the bones fixed with self-reinforced poly-L-lactide screws and those fixed with metallic screws. These results showed that self-reinforced poly-L-lactide screws, which have been used successfully in fractures and osteotomies in cancellous bone, are strong enough to support this more demanding fixation of weight-bearing bones.

Degradation and tissue replacement of an absorbable polyglycolide screw in the fixation of rabbit femoral osteotomies.

Degradation and tissue replacement of a totally absorbable polyglycolide screw, 4.5 millimeters in diameter and thirty millimeters in length, were studied histologically, morphometrically, and radiographically at sequential stages of resorption at as long as thirty-six weeks after fixation of a transverse distal femoral osteotomy in rabbits. The initial mean shear force to failure was 95.0 newtons for the specimens that had been fixed with the polyglycolide screw compared with 257.0 newtons for the distal part of the contralateral, intact femur. The physical appearance of the screw was unaltered at three weeks. The first histological signs of degradation were seen at six weeks, along the thread ridge. Premature breakage of the screw resulted in gross displacement and non-union of the osteotomy in one animal. The degradation of polyglycolide was accompanied histologically by a typical non-specific foreign-body reaction. This kind of tissue response seemed to be associated with an osteolytic proximal expansion of the implant cavity that was suggestive of increased pressure within the cavity during degradation of the screw. In eight specimens, a wall of new bone formed around this area of osteolysis and demarcated the implant cavity from the surrounding normal cancellous bone. Seventy-four per cent of the periphery and 28 per cent of the central core of the screw had been resorbed at twelve weeks. At thirty-six weeks, no polymeric material could be discerned, and the predominant tissue component within the implant cavity was loose connective tissue. The volume fractions of trabecular bone and hematopoietic bone marrow were significantly lower (p less than 0.01) than those of the intact, control side, but the degree of restoration of tissue varied considerably from animal to animal.

Acute dislocation of the patella. A prospective review of operative treatment.

We report a prospective study of 55 patients with acute primary patellar dislocation, all treated by operation and followed up for at least two years. Diagnosis was based on the history of a lateral displacement, with medial tenderness and a positive apprehension test; redislocations were excluded. Before operation, the difference in lateral shift on skyline views of the injured and control patellae was highly significant. At operation, rupture of the medial retinaculum of the patella was seen in all but one case. There were medial marginal fractures of the patella in 23 cases. Subjective results of the operation were excellent or good in 44 of the 55 at two years with a redislocation rate of only 9%. Most patients were able to return to the same level of sporting activity as before the injury.

The effect of osteotomy and osteosynthesis in the mandibular condyle. A radiologic and histologic study in sheep.

Eighteen oblique osteotomies in sheep mandibular condylar necks were fixed with self-reinforced poly-L-lactide (SR-PLLA) (n = 9) or stainless steel (n = 9) screws (core diameters 2.4, 2.7, 3.0, or 3.5 mm). No intermaxillary fixation (IMF) was applied. The follow-up periods were 6, 12, and 24 weeks, respectively, after which the sheep were killed, and the status of the condylar head was assessed radiographically and histologically. The results showed that the fixation had been adequate. Bony destruction, osteophytes, and flattening of the condylar head, however, were frequently observed in both groups, as compared with the unoperated contralateral condyle. Histologic studies revealed that the thickness of the condylar head cartilage had increased and that the boundaries of the different cell layers were irregular, as was the junction of cartilage and bone. The diameter of the screw did not seem to have any influence on the occurrence of either radiologic or histologic signs of condylar degeneration. These findings indicate that screw fixation of condylar fractures in the mandible without IMF might result in degenerative joint disease.

Use of bioabsorbable osteofixation devices in the hand.

Bioabsorbable internal fixation by means of pins, tacks, screws and miniplates offers an alternative to metallic osteofixation for the stabilization of small bone fractures, osteotomies, ligament injuries and fusions in the hand. The advantages of using them include avoidance of metallic-implant-related long-term complications and a secondary removal operation. Currently the most commonly used devices are made of poly L-lactide (PLLA) and copolymers of polylactides (P(L/DL)LA) and polyglycolide (PLGA). In areas of mechanical stress, the use of ultra-high-strength self-reinforced devices is recommended. Biomechanical studies on fresh frozen bones have shown that the fixation rigidity achieved with self-reinforced devices approaches that of metallic osteofixation methods. The reliability of modern implants has been confirmed in several experimental and clinical studies.

Osteolytic changes after polyglycolide pin fixation in chevron osteotomy.

Absorbable polyglycolide pins were used for fixation of 94 chevron osteotomies in 70 patients at the Department of Orthopaedics and Traumatology, Helsinki University Central Hospital, between 1986 and 1992. Postoperative osteolytic changes around the degrading pin occurred in 21 of 94 (22%) metatarsal heads. In 17 of 21 metatarsal heads, polydioxanone-coated polyglycolide pins were used. This type of pin has not been used since 1988. At follow-up, 16 of 21 osteolytic changes resolved completely and four partially resolved. In the remaining one, the osteolytic area remained visible after 6 years. Cystic changes in the metatarsal head, not attributable to the location of the absorbable implants, occurred in seven (7.4%) metatarsal heads and avascular necrosis of the entire metatarsal head in one (1.1%). Foreign body reaction occurred in six (6.3%) metatarsal heads and wound infection in three (3.2%) metatarsal heads. No association was observed between osteolytic changes and foreign body reaction or infection. Osteolysis in patients receiving polyglycolide implants only require observation, because associated symptoms with the radiographic findings are transient.

Ultrasound guidance for puncture and injection in the radiocarpal joint.

BACKGROUND: The use of intra-articular contrast agent has been shown to increase the diagnostic accuracy of wrist magnetic resonance (MR) in patients with suspected trauma of the wrist ligaments. Traditionally, the contrast agent has been applied under fluoroscopic guidance. PURPOSE: To present a method based on ultrasound guidance for the injection of intra-articular contrast agent in wrist MR. MATERIAL AND METHODS: One hundred eight patients (56 female and 52 male, mean age 36 years) referred for wrist MR arthrograms due to suspected ligament rupture were included in this retrospective study. The preferred injection point is about 1 cm distal to Lister's tubercle in the distal radius. A correct positioning of the injection needle can be ensured using ultrasound guidance. RESULTS: Using this technique, the injection was intra-articular in 93.5% of the 108 injections over a 2-year learning period. CONCLUSION: Ultrasound guidance of the contrast injection in radiocarpal MR arthrograms is a cost-effective and safe alternative to fluoroscopically guided procedures. Furthermore, the use of ultrasound guidance provides clues about possible fluid collections within the joint.

Benzylpenicillin ineffective for open fractures. Prospective study of 60 cases.

In a prospective study of 60 open fractures treated with prophylactic antibiotics, 10 developed infection with 2/40 Grades 1 and 2 fractures and 8/20 Grade 3 fractures. Intravenous penicillin was ineffective against Staphylococcus aureus and epidermidis, the most usual organisms causing infection in open fractures, as 62 percent of the organisms cultured from the initial culture and 92 percent of those cultured during infection were resistant to penicillin. For the second generation cephalosporins, the respective figures were 21 and 30 percent.

Comparison of absorbable self-reinforced multilayer poly-l-lactide and metallic plates for the fixation of mandibular body osteotomies: an experimental study in sheep.

Eighteen unfavorable transverse osteotomies were created in the mandibular body of sheep. Nine were fixed with self-reinforced poly-l-lactide and nine with metallic dynamic compression plates. Both plates were fixed with similar titanium screws. The follow-up times for radiographic, histologic, and microradiographic studies were 6, 12, and 24 weeks. With both methods, bony union with callus formation was accomplished by 6 weeks in all but one osteotomy in the metallic fixation group. There were no signs of plate failure.

Clindamycin versus cloxacillin in the treatment of 240 open fractures. A randomized prospective study.

BACKGROUND AND AIMS: Systemic administration of antibiotics is recommended and has proved to lower infection rates in open fractures. However, no antibiotic has proved to be superior to any other. MATERIAL AND METHODS: In a prospective study 227 patients with 240 open fractures were randomized to receive either clindamycin or cloxacillin for infection prevention. RESULTS: The overall infection rate was 15%. Infection occurred in 9.3% of the clindamycin treated and in 20% of the cloxacillin treated fractures (p < 0.05). In the Gustillo Type I and II open fractures all the pathogens causing infection were gram-positive, while in the Type III open fractures 21 pathogens (57%) were gram-positive and 16 (43%) gram-negative. In the clindamycin treated fractures the infection rates in Type I and II open fractures were 3.3 and 1.8%, respectively, while in the cloxacillin group they were 20 and 3.8%, respectively. Both clindamycin and cloxacillin showed low effectiveness in the treatment of Type III open fractures, the highest infection rates being 75 and 67%, respectively (Type III B). CONCLUSIONS: Clindamycin provides good antimicrobic coverage against the most common pathogens causing Type I and II open fracture infections. In the treatment of Type III open fractures additional administration of an antibiotic with good gram-negative coverage is recommended.

MR imaging in chronic rupture of the ulnar collateral ligament of the thumb.

PURPOSE: MR imaging has been shown as the best radiologic method for verifying and classifying acute ulnar collateral ligament (UCL) ruptures of the thumb. Our aim was to analyse the usefulness of MR also in old ruptures and to establish the most useful sequences. MATERIAL AND METHODS: Ten patients with an old UCL rupture of the thumb were preoperatively imaged using 1.5 T MR. Three radiologists blinded to the findings separately analysed the MR images of these patients and of 10 age-and sex-matched voluntary controls. MR findings of the patients were compared with those of surgery. RESULTS: The consensus diagnosis of an UCL rupture was accurate in all 10 patients. All controls were classified as having no UCL rupture. In 5 of the 7 patients with a surgically defined Stener or non-Stener lesion, the consensus diagnosis was the same as the operative diagnosis. Due to excessive scarring it was not possible to verify any Stener lesion intra-operatively in 3 patients. The most informative MR sequence was T2 TSE in the coronal plane, the second most informative was T1 SE with fat suppression in the coronal plane. CONCLUSION: An old UCL rupture is well verified by MR but typing of the lesion as either a Stener or non-Stener type is not always possible.

Conservative treatment of scaphoid fractures: a follow up study.

BACKGROUND AND AIMS: This investigation was made to elucidate the outcome of conservatively treated scaphoid fractures. MATERIAL AND METHODS: 63 patients with a scaphoid fracture were treated initially conservatively and examined retrospectively. The mean follow up time was 54 months. RESULTS: In this group bone union was achieved in 56 cases (89%). Three of the patients ended up to operation because of delayed union soon after conservative treatment and three nonunions were found in the follow up appointment. One fracture did not heal because of dislocation during cast treatment and was treated with operation. Incidence of osteoarthrosis and residual symptoms were studied in the group with totally conservative treatment. Osteoarthrosis was found in 19 (32%) wrists, but no correlation with wrist problems (pain, reduced grip strength or problems at work) was found. 20 (34%) of the patients complained residual symptoms. Most of the symptoms were mild and did not impair their ability to work or cause serious problems during free time. CONCLUSION: According to the present study conservative treatment is a safe method for the treatment of undislocated stabile scaphoid fractures.

Medetomidine--ketamine--diazepam anesthesia in the rabbit.

Orthopaedic operations were performed in 340 rabbits when developing biodegradable rods for the fixation of fractures. The rabbits were anaesthesized by injecting medetomidine combined with ketamine and diazepam (MKD) subcutaneously. The mortality due to the anaesthesia was zero. Arterial blood gas analyses showed a moderate decrease in the haemoglobin oxygen saturation and compensated respiratory acidosis, which was well tolerated by the animals. It is concluded that MKD anaesthesia is well suited for orthopaedic operations in the rabbit.

A histomorphological study on self-reinforced polyglycolide (SR-PGA) osteosynthesis implants coated with slowly absorbable polymers.

A total of 150 osteotomies of rabbits' distal femur were fixed with absorbable self-reinforced polyglycolide (SR-PGA) rods coated with slowly absorbable polymers. In order to reduce the degradation rate of the SR-PGA construction rods were coated with n-butyl-2-cyanoacrylate, polydioxanone (PDS), poly-beta-hydroxybutyrate (PHBA), or poly-l-lactide (PLLA). Biocompatibility and the rate of biodegradation were evaluated in histological, histomorphometric, microradiographic, and oxytetracycline labeling studies. PDS, PHBA, and PLLA coatings showed good biocompatibility although there were scattered fluid accumulations around the rod in each group. Cyanoacrylate coating seemed to inhibit cartilage regeneration and cause the formation of considerable amount of connective tissue around the implant. The PGA core of the rod had totally degraded in 24 to 36 weeks in each coating group. Cyanoacrylate and PDS coatings were not detectable after 6 weeks while PHBA and PLLA coatings were still observed after 48 weeks. There were five (14%) non-unions in the cyanoacrylate coating group, one (3%) in the PHBA coating group caused by a purulent infection and none in the PDS and PLLA coating groups.

Intramedullary fixation of cortical bone osteotomies with self-reinforced polylactic rods in rabbits.

Osteotomies of the femoral shaft in rabbits were fixed with intramedullary rods made of poly-L-lactic acid (SR-PLLA) and poly-DL/L-lactic acid (SR-PDLLA/PLLA). Follow up was from one week to 2 years. In the PLLA group, in 37 out of 40 osteotomies the fixation was firm and the bone was united. In the PDLLA/PLLA group, the fixation was firm in 30 out of 45, but in 13 of these angular deformity of more than 10 degrees had occurred. The fixation had failed in 15. No inflammatory or foreign body reaction was seen in either group. This study demonstrates that SR-PLLA rods are suitable fixation for cortical osteotomies in rabbits.

Do intramedullary rods of self-reinforced poly-L-lactide or poly-DL/L-lactide cause lactic acid acidosis in rabbits?

Intramedullary rods of self-reinforced poly-DL/L-lactic acid or poly-L-lactic acid were implanted in both femurs of ten rabbits for 60 weeks. Levels of arterial blood L- and D-lactate, pyruvate, pH, pCO2, base excess, standard bicarbonate, pO2 and O2-saturation were determined before implantation and 1, 3, 6, 12, 24, 36, 48 and 60 weeks after implantation. No significant increase in blood L- and D-lactate level was observed at any follow-up. Also, the blood acid-base balance remained normal throughout the study. Further studies on larger implants and on larger animals with follow-ups up to 5 years are recommended.

Ultra-high-strength absorbable self-reinforced polyglycolide (SR-PGA) composite rods for internal fixation of bone fractures: in vitro and in vivo study.

The ultra-high-strength, self-reinforced (SR) absorbable polymeric composites, consisting of reinforcement elements, like fibers, and of matrix polymer which have the same chemical element composition as reinforcement, were defined. A method to manufacture self-reinforced, absorbable polyglycolide (SR-PGA) rods of polyglycolide sutures (Dexon) by sintering them partially together at elevated temperature and pressure was presented. The rods with nominal diameters of 1.5 mm, 2.0 mm, 3.2 mm, and 4.5 mm showed initial bending modulus and strength values of 8-15 GPa and 220-405 MPa, respectively. Their initial shear strengths were 165-255 MPa. The smallest rods (diam. 1.5 mm) lost their mechanical strength after implantation in the subcutis of rabbits in 4-5 weeks while the thickest rods retained their strength over 8 weeks. The ultra-high-strength SR-PGA rods were concluded to be suitable for fixation of cancellous bone fractures, osteotomies, and epiphyseal plate fractures where the fixation is not exposed to excessive mechanical stresses and where the loads are predominantly of a shear nature.