Tibial condylar fractures involve a major weight-bearing joint and are serious injuries that result in functional impairment.1 Tibial condylar fractures compose 1% of all fractures and 5% to 8% of lower limb fractures.2,3 These fractures are most commonly the result of falls, motor vehicle accidents, and sports trauma.3 The Schatzker classification system is one method of classifying tibial plateau fractures. Schatzker type II fractures are intra-articular and are recognized as split depressed fractures of the lateral tibial plateau.4 To achieve and maintain the joint surface, the most common method of treating Schatzker type II fractures involves metallic screw fixation.4,5
Forged composites of raw particulate unsintered hydroxyapatite/poly-L-lactide (F-u-HA/PLLA) screws are highly suited for use in bone fixation owing to their bioactivity, bioresorbability, and retention of high mechanical strength.6 They also possess excellent biocompatibility and osteoconductivity, which promote direct bone bonding and new bone formation.7,8 Furthermore, F-u-HA/PLLA devices are radioopaque. Thus, these implants have many potential applications in various clinical fields, including orthopedic, oral maxillary/mandibular facial, and traumatic surgeries.9–13
The clinical application and efficacy of F-u-HA/PLLA screws have been reported for the treatment of pediatric lateral condyle humerus fractures and adult ankle fractures.14,15 However, the efficacy of F-u-HA/PLLA screws in the treatment of tibial plateau fractures, which disrupt the major weight-bearing surface, has not been verified. The purpose of this study was to investigate the efficacy of F-u-HA/PLLA screws for the treatment of Schatzker type II fractures in adult patients.
Materials and Methods
From January 2005 to December 2010, closed displaced lateral tibial condylar fractures (Schatzker type II4) in 7 patients were treated using F-u-HA/PLLA screws (OSTEOTRANS; Zimmer, Warsaw, Indiana). During this period, all patients with Schatzker type II fractures and intra-articular displacement of more than 2 mm were treated using F-u-HA/PLLA screws. The average age of the patients was 51.1 years (range, 17–79 years) (Table). Clinical and radiographic follow-up were scheduled postoperatively. Radiographs were evaluated for joint depression, fracture healing, breakage of screws, and radioopacity of screws. Clinical assessments included pain, range of motion, delayed inflammatory reaction, and foreign body reactions.
Patient Demographics and Pre- and Postoperative Outcomes
Surgery was performed under spinal anesthesia. Following exposure, the lateral displaced fragment was reduced anatomically and temporarily fixed using K-wires. Joint reconstruction was confirmed using an image intensifier. Hydroxyapatite or ß-tricalcium phosphate granules were grafted in 4 of 7 patients. Two F-u-HA/PLLA screws (6.5 mm) with F-u-HA/PLLA washers were inserted from the lateral side of the tibial plateau into the medial side in 6 of 7 patients (Figure 1). Two 6.5-mm and one 4.5-mm F-u-HA/PLLA screws were used in 1 of the 7 patients. Postoperatively, patients were prohibited from bearing weight for 6 weeks. Patients were instructed to gradually increase knee motion starting 2 weeks postoperatively.
Intraoperative view of a fracture fixed using 2 forged composites of raw particulate unsintered hydroxyapatite/poly-L-lactide screws and washers.
Average follow-up was 44 months (range, 15–78 months). All fractures were successfully healed. Average joint depression improved from 4.7 mm (range, 2–9 mm) preoperatively to 0.4 mm (range, 0–1 mm) postoperatively and was maintained at 0.4 mm (range, 0–1 mm) at final follow-up (Figures 2–3). Whole shadows of F-u-HA/PLLA screws were observed during the follow-up period. Breakage of screws, osteolysis, and a radiolucent zone around the screws were not observed at final follow-up. Average knee flexion and extension were 134° (range, 110° to 150°) and −1° (range, −10° to 0°), respectively. No patient had wound infection, late aseptic tissue response, or foreign body reaction postoperatively. No patient reported pain at final follow-up, and all had returned to their preinjury level of work and activities of daily living.
Preoperative anteroposterior (A) and lateral (B) radiographs of a left lateral tibial condylar fracture (Schatzker type II).
Postoperative anteroposterior (A) and lateral (B) radiographs of the left lateral tibial condylar fracture (Schatzker type II) from Figure 2.
This study showed that F-u-HA/PLLA screws are useful for the treatment of lateral tibial condylar fractures. It is well-known that joint depression and incongruity lead to pain and functional impairment in tibial condylar fractures1 and that metallic screw fixation is the most common method of treating tibial plateau fractures.4,5 Generally, bone fixation devices used to treat fractures require much higher initial mechanical strength than natural cortical bone, which has a bending strength of 200 MPa.6 The F-u-HA/PLLA material has an initial bending strength of 270 MPa6; however, the endurance of F-u-HA/PLLA screws on full weight bearing has not been verified. In the current study, no breakage of F-u-HA/PLLA screws was observed, and the joint surface was maintained at final follow-up in all patients, leading to no reports of pain. Therefore, although this case series was performed for the lateral tibial condyle, where the main loading force does not pass through, F-u-HA/PLLA screws seem to be strong enough for full weight bearing and this area.
Earlier bioresorbable implants used to treat fractures were made of PLLA and polyglycolic acid. The F-u-HA/PLLA devices are made of a composite of uncalcined and unsintered HA and PLLA and have several advantages compared with PLLA and polyglycolic acid devices. First, F-u-HA/PLLA devices promote direct bone bonding. An in vivo study reported that direct bony contact was observed on the F-u-HA/PLLA device after implantation in the bone defect, whereas a fibrous tissue layer was seen on the PLLA device.7 In addition, new bone formation was observed on the PLLA device within 2 weeks of implantation, and the bone gradually grew along the surface of the device.7 These osteological bioactivities of the F-u-HA/PLLA device may contribute to the early positional stability of the implant in bone. Second, unlike polyglycolic acid and PLLA devices, F-u-HA/PLLA devices have radio-opacity and therefore can be observed on postoperative radiographs. If the F-u-HA/PLLA screw is broken after surgery, this can be detected on follow-up radiographs.
Such bioresorbable devices also possess biodegradable features. The earlier biodegradable implants such as polyglycolic acid or PLLA caused issues. Polyglycolic acid implants degrade rapidly and cause tissue reactions, such as skin ulcers or aseptic tissue responses.16,17 Implants of PLLA only degrade after many years, and foreign body reactions and late aseptic swelling have occurred owing to a long degradation period and uneven PLLA fragments, which are the result of irregular heterogeneous hydrolysis.18,19 Akagi et al20 reported severe infiltration of histiocyte cells in the implantation site on histology at 5 years after PLLA screw insertion. On the other hand, the F-u-HA/PLLA composite structure is designed to allow homogeneous hydrolysis and steady degradation of the PLLA throughout the degradation process. This uniform hydrolysis brings steady release of small amounts of fragments as the materials degrade, resulting in the decreased adverse tissue response.6 In the current study, there were no tissue reactions, late aseptic swelling, or foreign body reactions at final follow-up; however, whole shadows of F-u-HA/PLLA screws were still observed during the follow-up period. Further follow-up is necessary to confirm the reaction until the F-u-HA/PLLA screws are resorbed.
This study had several limitations. There was no group, such as patients with nonoperative treatment or metallic screw fixation, for comparison. In addition, only a few cases were included. However, to the authors' knowledge, this is the first study reporting successful outcomes for lateral tibial condylar fractures treated using F-u-HA/PLLA screws. The authors believe that F-u-HA/PLLA screws could be an alternative option for the treatment of lateral tibial condylar fractures. Also, F-u-HA/PLLA devices have the potential to be used for additional clinical indications in fracture treatment as the next-generation material.
Lateral tibial condylar fractures were successfully treated using F-u-HA/PLLA screws. These screws could be an alternative option for the treatment of lateral tibial condylar fractures.
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Patient Demographics and Pre- and Postoperative Outcomes
|Patient Age, y/Sex||Side||Implant||Joint Depression, mm||Flexion||Extension||Follow-up, mo|
|68/Female||Left||Two 6.5-mm cannulated screws||5||0||0||130°||0°||75|
|58/Female||Left||Two 6.5-mm cannulated screws||2||0||0||140°||0°||30|
|55/Female||Left||Two 6.5-mm cannulated screws||7||0||0||120°||0°||15|
|49/Female||Left||Two 6.5-mm cannulated screws||2||1||1||145°||−10°||67|
|32/Male||Right||Two 6.5-mm cannulated screws||2||0||0||150°||0°||28|
|17/Male||Right||Two 6.5-mm cannulated screws||6||1||1||145°||0°||15|
|79/Female||Right||Two 6.5-mm and one 4.5-mm cannulated screws||9||1||1||110°||0°||78|