Although some reports suggest that taper-slip cemented stems may be associated with a higher periprosthetic femoral fractures rate than composite-beam cemented stems, few studies have focused on the biomaterial effect of the polished material on the stem–cement interface. The purpose of this study was to investigate the relationship between surface roughness of materials and bone cement. Four types of metal discs—cobalt-chromium-molybdenum alloy (CoCr), stainless steel alloy 316 (SUS), and two titanium alloys (Ti-6Al-4V and Ti-15Mo-5Zr-3Al)—were prepared. Five discs of each material were produced with varying degrees of surface roughness. In order to evaluate surface wettability, the contact angle was measured using the sessile drop method. A pin was made using two bone cements and the frictional coefficient was assessed with a pin-on-disc test. The contact angle of each metal increased with decreasing surface roughness and the surface wettability of metal decreased with higher degrees of polishing. With a surface roughness of Ra = 0.06 μm and moderate viscosity bone cement, the frictional coefficient was significantly lower in CoCr than in SUS (p = 0.0073). In CoCr, the low adhesion effect with low frictional coefficient may result in excessive taper-slip, especially with the use of moderate viscosity bone cement.

Background and Objectives: Spinal minimally invasive surgery (MIS) experts at the university hospital worked as a team to develop a new treatment algorithm for pyogenic spondylodiscitis in lumbar and thoracic spines. They modified a flow chart introduced for this condition in a pre-MIS era to incorporate MIS techniques based on their extensive experiences accumulated over the years, both in MIS for degenerative lumbar diseases and in the treatment of spine infections. The MIS procedures incorporated in this algorithm consisted of percutaneous pedicle screw (PPS)–rod fixation and transpsoas lateral lumbar interbody fusion (LLIF). The current study analyzed a series of 34 patients treated with prospective selection of the methods according to this new algorithm. Materials and Methods: The algorithm first divided the patients into those who had escaped complicated disease conditions, such as neurologic impairment, extensive bone destruction, and the need to be mobilized without delay (Group 1) (19), and those with complicated pyogenic spondylodiscitis (Group 2) (15). Group 1 had image-guided needle biopsy followed by conservative treatment alone with antibiotics and a spinal brace (12) (Group 1-A) or a subsequent addition of non-fused PPS–rod fixation (7) (Group 1-B). Group 2 underwent an immediate single-stage MIS with non-fused PPS–rod fixation followed by posterior exposure for decompression and debridement through a small midline incision (12) (Group 2-A) or an additional LLIF procedure after an interval of 3 weeks (3) (Group 2-B). Results: All patients, except four, who either died from causes unrelated to the spondylodiscitis (2) or became lost to follow up (2), were cured of infection with normalized CRP at an average follow up of 606 days (105–1522 days). A solid interbody fusion occurred at the affected vertebrae in 15 patients (50%). Of the patients in Group 2, all but two regained a nearly normal function. Despite concerns about non-fused PPS–rod instrumentation, only seven patients (21%) required implant removal or replacement. Conclusions: Non-fused PPS–rod placements into infection-free vertebrae alone or in combination with posterior debridement through a small incision worked effectively in providing local stabilization without contamination of the metal implant from the infected tissue. MIS LLIF allowed for direct access to the infected focus for bone grafting in cases of extensive vertebral body destruction.

Background and Objectives: Clinicians are required to manage a growing number of elderly patients with several medical comorbidities, and invasive surgical treatments are sometimes not advisable for these patients. The aim of this study was to evaluate the efficacy of minimally invasive intraspinal canal treatment, trans-sacral canal plasty (TSCP), for patients with and without failed back surgery syndrome (FBSS). Materials and Methods: A multicenter analysis was conducted. TSCP was performed in patients with chronic low back pain and leg pain due to lumbar spinal disorders. An adhesiolysis by TSCP was carried out, then a mixture of steroid and local anesthesia was injected. Visual Analog Scales (VAS) for low back pain and leg pain, and complications were evaluated. Results: A total of 271 patients with a minimum 6-month follow-up were enrolled. There were 80 patients who had a history of previous lumbar spinal surgery (F group), and 191 patients without previous lumbar spinal surgery (N group). There were no significant differences in sex and age between the two groups. VAS scores for low back pain (N group/F group) preoperatively, immediately postoperatively, and 1 month, 3 months and 6 months postoperatively, were 51/52 mm, 24/26 mm, 33/34 mm, 30/36 mm, and 30/36 mm, respectively. VAS scores for leg pain were 69/67 mm, 28/27 mm, 39/41 mm, 36/43 mm, and 32/40 mm, respectively. Both VAS scores for low back pain and leg pain were significantly decreased from baseline to final follow-up in both groups (p < 0.01). However, VAS scores for leg pain at 3 months and 6 months postoperatively were significantly higher in F group (p < 0.05). There were three catheter breakages (2/3 in F group), and one dural tear in F group. Conclusions: TSCP significantly reduced both VAS scores for low back and leg pain in patients with and without FBSS. However, co-existence of intractable epidural adhesion might be associated with less improvement in FBSS.

The modified Spitzy shelf acetabuloplasty for the dysplastic hip

Background and Objectives: Proximal junctional kyphosis (PJK) and failure (PJF), the most prevalent complications following long-segment thoracolumbar fusions for adult spinal deformity (ASD), remain lacking in defined preventive measures. We studied whether one of the previously reported strategies with successful results—a prophylactic augmentation of the uppermost instrumented vertebra (UIV) and supra-adjacent vertebra to the UIV (UIV + 1) with polymethylmethacrylate (PMMA)—could also serve as a preventive measure of PJK/PJF in minimally invasive surgery (MIS). Materials and Methods: The study included 29 ASD patients who underwent a combination of minimally invasive lateral lumbar interbody fusion (MIS-LLIF) at L1-2 through L4-5, all-pedicle-screw instrumentation from the lower thoracic spine to the sacrum, S2-alar-iliac fixation, and two-level balloon-assisted PMMA vertebroplasty at the UIV and UIV + 1. Results: With a minimum 3-year follow-up, non-PJK/PJF group accounted for fifteen patients (52%), PJK for eight patients (28%), and PJF requiring surgical revision for six patients (21%). We had a total of seven patients with proximal junctional fracture, even though no patients showed implant/bone interface failure with screw pullout, probably through the effect of PMMA. In contrast to the PJK cohort, six PJF patients all had varying degrees of neurologic deficits from modified Frankel grade C to D3, which recovered to grades D3 and to grade D2 in three patients each, after a revision operation of proximal extension of instrumented fusion with or without neural decompression. None of the possible demographic and radiologic risk factors showed statistical differences between the non-PJK/PJF, PJK, and PJF groups. Conclusions: Compared with the traditional open surgical approach used in the previous studies with a positive result for the prophylactic two-level cement augmentation, the MIS procedures with substantial benefits to patients in terms of less access-related morbidity and less blood loss also provide a greater segmental stability, which, however, may have a negative effect on the development of PJK/PJF.