Abstract The cyclic monophosphate nucleotides (cyclic adenosine monophosphate [cAMP] and cyclic guanosine monophosphate [cGMP]) are found ubiquitously in mammalian cells and act as second messenger transducers to effect the intracellular actions of a variety of hormones, cytokines, and neurotransmitters. In turn, these nucleotides also modulate the signal transduction processes regulated by a range of cytokines and growth factors. Previously, we have reported that pentoxifylline, a nonselective phosphodiesterase (PDE) inhibitor, can promote osteoblastic differentiation by elevating intracellular cAMP levels and, consequently, enhance bone formation in vivo and in vitro. In this study, reverse-transcription polymerase chain reaction (RT-PCR) analysis of the osteoblastic cell lines, MC3T3-E1 and ST2 revealed the presence of PDE1, PDE2, PDE3, PDE4, PDE7, PDE8, and PDE9. We examined the effect of selective inhibitors for a respective PDE isozyme on the capacity of bone morphogenetic protein 4 (BMP-4)-induced alkaline phosphatase (ALP) activity, a cellular differentiation marker, in cells with osteogenetic potential. The results indicate that selective inhibitors for PDE2, PDE3, and PDE4 enhanced the BMP-4-induced ALP activity in a dose-dependent manner in ST2 cells but not in MC3T3-E1 cells. Northern blot analysis also revealed that the selective inhibitors for PDE2, PDE3, and PDE4 enhanced the levels of expression of messenger RNAs (mRNAs) of ALP, osteopontin (OP), and collagen type I in ST2 cells but not in MC3T3-E1 cells except for the treatment with PDE4 inhibitor. Given these data, we conclude that PDE isozymes are involved in the modulation of osteoblastic differentiation mainly at an early stage. Additionally, selective inhibitors for PDE2, PDE3, and PDE4 appear to promote the differentiation of osteogenic precursor cells toward an osteoblastic phenotype.
BACKGROUND Hybrid total hip arthroplasty (THA) commonly recognized as cementless hemi-spherical acetabular component combined with cemented femoral stem. We have done so called “reverse” hybrid THA with cemented socket and cementless stem and compared with all-cemented THAs. PATIENTS AND METHODS We have been collecting data on total hip arthroplasty since November, 1993. Reverse hybrid hip replacements were used mainly from February, 2001. We evaluated data on 272 reverse hybrid THAs (223 patients) from this year onward until May, 2010, and compared the results with those from 283 all-cemented THAs (237 patients) between 1993 and May, 2010. Eighty percent or more of patients had diagnosed as secondary osteoarthritis of the hip joint due to dysplasia in our hospitals. Highly cross linked ultrahigh molecular polyethylene (CLP) socket was introduced in October, 1999. We used conventional (not cross linked polyethylene) socket for 82 hips (cemented group-1) operated before October, 1999 and CLP socket for 201 hips (cemented group-2) in all-cemented cases. We used the Kaplan-Meier method for estimation of prosthesis survival and relative risk of revision. The endpoint was radiological loosening or revision. Socket linear wear rates were also assessed in radiographically. Clinical assessment was performed using the Japanese Orthopedic Association (JOA) scores and Merle d9Aubigne & Postel scores. RESULTS We have 12 hips (11 sockets and 1 stem) with radiological loosening in all cemented series and no hips in reverse hybrid series. A case with stem loosening in all cemented THAs had fractured stem without bony support due to massive osteolysis caused by heavy polyethylene wear. All of the loosening cases had conventional polyethylene socket and six of them were revised. Socket linear wear rates were calculated as 0.171 +/− 0.069, 0.030+/− 0.027, and 0.035+/− 0.026 mm per year for cemented group-1, group-2 and reverse hybrid cases, respectively. Clinical scores were significantly improved those at the time of final follow up compared with those of preoperative assessment. There were significant differences between conventional and cross linked polyethylene cases. We found no significant difference survival to that from cemented THR at 12 years (all cemented: 96.1% (95% CI: 92.7–99.1); reverse hybrid: 100%) (Figure 1). DISCUSSION AND CONCLUSION With a follow-up of up to 12 years, reverse hybrid THAs performed well, and similarly to all-cemented THRs from the same time period. The reason for loosening was mainly bone loss and osteolysis due to polyethylene socket wear. It is no problem if the stem was installed by cemented or cementless fixation, because the rates of stem loosening were very low in the current study. The reverse hybrid method might therefore be an alternative to all-cemented THR. Longer follow-up time is needed to evaluate whether reverse hybrid hip arthroplasty has any advantages over all-cemented THA.
BACKGROUND Acetabular defects are encountered in both primary total hip arthroplasty (THA) in patients with developmental dysplasia of the hip (DDH) and in revision THA. The purpose of this study was to evaluate the clinical and radiographic results of one method of acetabular reconstruction for THA using a hydroxyapatite (HA) block with either an autogenous graft or allograft of impacted morsellized bone in conjunction with a cemented socket. METHODS Fourteen hips in 14 patients (all female; average age, 64 years) were treated with the above technique in primary (11 DDH) or revision THA (three loosened sockets). All patients were followed clinically in a prospective fashion, and radiographs were analyzed retrospectively. One initial patient had 16-year follow-up, whereas the remaining 13 patients had follow-up between four and 5.5 years. RESULTS No acetabular components were revised, including the socket of 16-year postoperative case which remains rigidly fixed and supported by the graft and HA block with only mild polyethylene wear and minor osteolysis. The mean Japanese Orthopaedic Association (JOA) score for the hips improved from 37 points preoperatively to 90 points postoperatively. CONCLUSIONS The authors report very good results of acetabular reconstruction with the use of these biomaterials in conjunction with impaction morsellized bone graft in THA. Osteointegration and good clinical outcome were achieved in all of cases. However longer-term outcome should be the subject of further investigation, as the majority of these patients had only mid-term follow-up of 4 to 5.5 years.
BACKGROUNDThere is no report of additional type of bulk bone grafting (Ad-BG) method with impaction morselized bone graft for reconstruction of shallow dysplastic hip in total hip arthroplasty. The...
