Makoto Ohe, Hiroshi Moridaira, Satoshi Inami, Daisaku Takeuchi, Yutaka Nohara and Hiroshi Taneichi
Instrumentation failure caused by the loosening of pedicle screws (PSs) in patients with osteoporosis is a serious problem after spinal surgery. The addition of a thin hydroxyapatite (HA) surface coating applied by using a sputtering process was reported recently to be a promising method for providing bone conduction around an implant without a significant risk of coating-layer breakage. In this study, the authors evaluated the biomechanical and histological features of the bone-implant interface (BII) of PSs with a thin HA coating in an in vivo porcine osteoporotic spine model.
Three types of PSs (untreated/standard [STPS], sandblasted [BLPS], and HA-coated [HAPS] PSs) were implanted into the thoracic and lumbar spine (T9–L6) of 8 mature Clawn miniature pigs (6 ovariectomized [osteoporosis group] and 2 sham-operated [control group] pigs). The spines were harvested from the osteoporosis group at 0, 2, 4, 8, 12, or 24 weeks after PS placement and from the control group at 0 or 24 weeks. Their bone mineral density (BMD) was measured by peripheral quantitative CT. Histological evaluation of the BIIs was conducted by performing bone volume/tissue volume and bone surface/implant surface measurements. The strength of the BII was evaluated with extraction torque testing.
The BMD decreased significantly in the osteoporosis group (p < 0.01). HAPSs exhibited the greatest mean extraction peak torque at 8 weeks, and HAPSs and BLPSs exhibited significantly greater mean torque than the STPSs at 12 weeks (p < 0.05). The bone surface/implant surface ratio was significantly higher for HAPSs than for STPSs after 2 weeks (p < 0.05), and bonding between bone and the implant surface was maintained until 24 weeks with no detachment of the coating layer. In contrast, the bone volume/tissue volume ratio was significantly higher for HAPSs than for BLPSs or STPSs only at 4 weeks.
Using PSs with a thin HA coating applied using a sputtering process strengthens bonding at the BII, which might improve early implant fixation after spinal surgery for osteoporosis. However, the absence of increased bone mass around the screw remains a concern; prescribing osteoporosis treatment to improve bone quality might be necessary to prevent fractures around the screws.
Hiroshi Taneichi, Kota Suda, Tomomichi Kajino, Akira Matsumura, Hiroshi Moridaira and Kiyoshi Kaneda
There are no published reports of unilateral transforaminal lumbar interbody fusion (TLIF) in which two Brantigan I/F cages were placed per level through a single portal to achieve bilateral anterior-column support. The authors describe such a surgical technique and evaluate the clinical outcomes of this procedure.
Data obtained in 86 (93.5%) of the first 92 consecutive patients who underwent the procedure were retrospectively reviewed; the minimum follow-up duration was 2 years. The clinical outcomes were evaluated using the Japanese Orthopaedic Association (JOA) scoring system. Disc height, disc angle, cage positioning in the axial plane, and fusion status were radiographically evaluated.
The mean follow-up period was 33.8 months. The mean improvement in the JOA score was 77.2%. Fusion was successful in 93% of the cases. According to the Farfan method, the mean anterior and posterior disc heights increased from 20.2 and 16.9% preoperatively to 35.9 and 22.7% at follow up, respectively (p < 0.01). The mean disc angle increased from 4.8° preoperatively to 7.5° at last follow-up examination (p < 0.01). Two cages were correctly placed to achieve bilateral anterior-column support in greater than 85% of the cases. The following complications occurred: hardware migration in two patients and deep infection cured by intravenous antibiotic therapy in one patient.
Unilateral TLIF involving the placement of two Brantigan cages per level led to good clinical results. Two Brantigan cages were adequately placed via a single portal, and reliable bilateral anterior-column support was achieved. Although the less invasive unilateral approach was used, the outcomes were as good as those in many reported series of posterior lumbar interbody fusion in which the Brantigan cages were placed via the bilateral approach.
Takafumi Chiba, Satoshi Inami, Hiroshi Moridaira, Daisaku Takeuchi, Tsuyoshi Sorimachi, Haruki Ueda, Makoto Ohe, Hiromichi Aoki, Takuya Iimura, Yutaka Nohara and Hiroshi Taneichi
The aim of this study was to show the surgical results of growing rod (GR) surgery with prior foundation surgery (PFS) and sublaminar taping at an apex vertebra.
Twenty-two early-onset scoliosis (EOS) patients underwent dual GR surgery with PFS and sublaminar taping. PFS was performed prior to rod placement, including exposure of distal and proximal anchor areas and anchor instrumentation filled with a local bone graft. After a period of 3–5 months for the anchors to become solid, dual rods were placed for distraction. The apex vertebra was exposed and fastened to the concave side of the rods using sublaminar tape. Preoperative, post–GR placement, and final follow-up radiographic parameters were measured. Complications during the treatment period were evaluated using the patients’ clinical records.
The median age at the initial surgery was 55.5 months (range 28–99 months), and the median follow-up duration was 69.5 months (range 25–98 months). The median scoliotic curves were 81.5° (range 39°–126°) preoperatively, 30.5° (range 11°–71°) after GR placement, and 33.5° (range 12°–87°) at the final follow-up. The median thoracic kyphotic curves were 45.5° (range 7°–136°) preoperatively, 32.5° (range 15°–99°) after GR placement, and 42° (range 11°–93°) at the final follow-up. The median T1–S1 lengths were 240.5 mm (range 188–305 mm) preoperatively, 286.5 mm (range 232–340 mm) after GR placement, and 337.5 mm (range 206–423 mm) at the final follow-up. Complications occurred in 6 patients (27%). Three patients had implant-related complications, 2 patients had alignment-related complications, and 1 patient had a wound-related complication.
A dual GR technique with PFS and sublaminar taping showed effective correction of scoliotic curves and a lower complication rate than previous reports when a conventional dual GR technique was used.