Should central osteophytes within the articular cartilage of the lateral compartment be considered when determining the indication of unicompartmental knee arthroplasty for medial osteoarthritis?

Patients with central osteophytes in the lateral compartment may be poor candidates for unicompartmental knee arthroplasty (UKA) for medial knee arthritis given the thin overlying articular cartilage above the central osteophytes that is inadequate for supporting weight-bearing after UKA. Therefore, attempts should be made to detect central osteophytes to confirm suitability for UKA.

Octacalcium Phosphate/Gelatin Composite (OCP/Gel) Enhances Bone Repair in a Critical-sized Transcortical Femoral Defect Rat Model.

BACKGROUND: Bone grafting is widely used to treat large bone defects. A porous composite of a bioactive octacalcium phosphate material with gelatin sponge (OCP/Gel) has been shown to biodegrade promptly and be replaced with new bone both in animal models of a membranous bone defect and a long bone defect. However, it is unclear whether OCP/Gel can regenerate bone in more severe bone defects, such as a critical-size transcortical defect. QUESTIONS/PURPOSES: Using an in vivo rat femur model of a standardized, transcortical, critical-size bone defect, we asked: Compared with a Gel control, does OCP/Gel result in more newly formed bone as determined by (1) micro-CT evaluation, (2) histologic and histomorphometric measures, and (3) osteocalcin staining and tartrate-resistant acid phosphatase staining? METHODS: Thirty-four 12-week-old male Sprague-Dawley rats (weight 356 ± 25.6 g) were used. Gel and OCP/Gel composites were prepared in our laboratory. Porous cylinders 3 mm in diameter and 4 mm in height were manufactured from both materials. The OCP/Gel and Gel cylinders were implanted into a 3-mm-diameter transcortical critical-size bone defect model in the left rat femur. The OCP/Gel and Gel were randomly assigned, and the cylinders were implanted. The biological responses of the defect regions were evaluated radiologically and histologically. At 4 and 8 weeks after implantation, CT evaluation, histological examination of decalcified samples, and immunostaining were quantitatively performed to evaluate new bone formation and remaining bone graft substitutes and activity of osteoblasts and osteoclast-like cells (n = 24). Qualitative histological evaluation was performed on undecalcified samples at 3 weeks postimplantation (n = 10). CT and decalcified tissue analysis was not performed blinded, but an analysis of undecalcified specimens was performed under blinded conditions. RESULTS: Radiologic analysis revealed that the OCP/Gel group showed radiopaque regions around the OCP granules and at the edge of the defect margin 4 weeks after implantation, suggesting that new bone formation occurred in two ways. In contrast, the rat femurs in the Gel group had a limited radiopaque zone at the edge of the defect region. The amount of new bone volume analyzed by micro-CT was higher in the OCP/Gel group than in the Gel group at 4 and 8 weeks after implantation (​​4 weeks after implantation: OCP/Gel versus Gel: 6.1 ± 1.6 mm 3 versus 3.4 ± 0.7 mm 3 , mean difference 2.7 [95% confidence interval (CI) 0.9 to 4.5]; p = 0.002; intraclass correlation coefficient [ICC] 0.72 [95% CI 0.29 to 0.91]; 8 weeks after implantation: OCP/Gel versus Gel: 3.9 ± 0.7 mm 3 versus 1.4 ± 1.1 mm 3 , mean difference 2.5 [95% CI 0.8 to 4.3]; p = 0.004; ICC 0.81 [95% CI 0.47 to 0.94]). Histologic evaluation also showed there was a higher percentage of new bone formation in the OCP/Gel group at 4 and 8 weeks after implantation (​​4 weeks after implantation: OCP/Gel versus Gel: 31.2% ± 5.3% versus 13.6% ± 4.0%, mean difference 17.6% [95% CI 14.2% to 29.2%]; p < 0.001; ICC 0.83 [95% CI 0.53 to 0.95]; 8 weeks after implantation: OCP/Gel versus Gel: 28.3% ± 6.2% versus 9.5% ± 1.9%, mean difference 18.8% [95% CI 11.3% to 26.3%]; p < 0.001; ICC 0.90 [95% CI 0.69 to 0.97]). Bridging of the defect area started earlier in the OCP/Gel group than in the Gel group at 4 weeks after implantation. Osteocalcin immunostaining showed that the number of mature osteoblasts was higher in the OCP/Gel group than in the Gel group at 4 weeks (OCP/Gel versus Gel: 42.1 ± 6.5/mm 2 versus 17.4 ± 5.4/mm 2 , mean difference 24.7 [95% CI 16.2 to 33.2]; p < 0.001; ICC 0.99 [95% CI 0.97 to 0.99]). At 4 weeks, the number of osteoclast-like cells was higher in the OCP/Gel composite group than in the Gel group (OCP/Gel versus Gel: 3.2 ± 0.6/mm 2 versus 0.9 ± 0.4/mm 2 , mean difference 2.3 [95% CI 1.3 to 3.5]; p < 0.001; ICC 0.79 [95% CI 0.35 to 0.94]). CONCLUSION: OCP/Gel composites induced early bone remodeling and cortical bone repair in less time than did the Gel control in a rat critical-size, transcortical femoral defect, suggesting that OCP/Gel could be used as a bone replacement material to treat severe bone defects. CLINICAL RELEVANCE: In a transcortical bone defect model of critical size in the rat femur, the OCP/Gel composite demonstrated successful bone regeneration. Several future studies are needed to evaluate the clinical application of this interesting bone graft substitute, including bone formation capacity in refractory fracture and spinal fusion models and the comparison of bone strength after repair with OCP/Gel composite to that of autologous bone.

A Right Angle Guide for Distal Tuberosity Osteotomy With Medial Open Wedge High Tibial Osteotomy for Varus Knee Osteoarthritis.

Medial open wedge high tibial osteotomy (OWHTO) is usually performed with proximal tuberosity osteotomy or setting the osteotomy line proximal to the tuberosity. However, OWHTO can result in patellofemoral complications due to postoperative patella infera. A new OWHTO technique, biplanar osteotomy with a distal tuberosity osteotomy, was reported in 2004 to prevent postoperative patella infera. To ensure that the 2 osteotomy lines maintain perpendicular, we describe the OWHTO procedure with a distal tuberosity osteotomy technique using a TriS Medial HTO Plate System (Olympus Terumo Biomaterials Corp., Tokyo, Japan) and a right angle guide we developed. In this Technical Note, we describe the procedure and advantages, risks, and limitations, as well as the pearls and pitfalls based on our experience.

Impact of simultaneous hydrolysis of OCP and PLGA on bone induction of a PLGA-OCP composite scaffold in a rat femoral defect.

Effect of the simultaneous hydrolysis of octacalcium phosphate (OCP) and poly (lactic-co-glycolic acid) (PLGA) was investigated on its osteoconductivity. PLGA soaked in phosphate buffered saline with 0%, 20%, and 40% OCP at 37°C for eight weeks indicated that when the OCP dose was increased, 1) the weight loss of PLGA increased, 2) the glass transition temperature of the PLGAs decreased, 3) the saturation degree in the saline moved to nearly saturated condition with respect to hydroxyapatite (HA) but was undersaturated with respect to OCP, and 4) OCP tended to convert to HA by X-ray diffraction and Fourier transform infrared spectroscopy. OCP/PLGA composites of 20% and 40% with more than 92% porosity were produced by combining OCP granules with 1,4-dioxane-solubilizing PLGA followed by lyophilization and then subjected to four- and eight-week in vivo implantation tests in 3 mm diameter rat femora defects. Microfocus X-ray computed tomography, histochemical and histomorphometric analyses showed that while bone formation was very limited with PLGA implantation, the extent of repair tended to increase with increasing OCP content in the PLGA, coupled with PLGA degradation, and bridge the defects with trabecular bone. Tartrate-resistant acid phosphatase-positive osteoclast-like cells were accumulated four weeks after implantation, while osteocalcin-positive osteoblastic cells appeared later at eight weeks, especially in 40% OCP/PLGA. These results suggest that OCP hydrolysis, with phosphate ion release, enhances PLGA hydrolysis, probably through the acid catalysis function of the protons supplied during the hydrolysis of OCP, thereby inducing PLGA biodegradation and new bone formation in the femoral defects. STATEMENT OF SIGNIFICANCE: Octacalcium phosphate (OCP) enhances osteoblasts and osteocytes differentiations during its hydrolysis accompanying inorganic ions exchange in this material. The present study found that the advancement of OCP hydrolysis under physiological conditions had an effect on poly (lactic-co-glycolic acid) (PLGA) degradation through its chemical environmental change around OCP, which was ascertained by the decreases in weight loss and glass transition temperature of PLGA with increasing the dose of OCP co-present. Rat femur-penetrated standardized severe defects were found to repair through bridging the cortical region defect margin. PLGA degradation could be enhanced through an acid catalyst function by protons derived from inorganic phosphate (Pi) ions through OCP hydrolysis under bone forming condition, resulting in showing a prominent bone regenerative capacity in OCP/PLGA composite materials.

Chemical Stability-Sensitive Osteoconductive Performance of Octacalcium Phosphate Bone Substitute in an Ovariectomized Rat Tibia Defect.

The purpose of this study was to investigate whether the chemical condition of osteoporotic serum affects the chemical stability of octacalcium phosphate (OCP) and its osteoconductive property. The in vitro chemical dissolution in osteoporotic ovariectomized (OVX)-simulated conditions was analyzed. OCP and its composite form with gelatin (OCP/Gel), containing specific amounts of OCP (either 17% or 44% by weight), were used as experimental materials. The degrees of supersaturation (DS) of the OVX-simulated buffer solutions, containing distinct inorganic phosphate (Pi) ion concentrations, after immersing OCP or OCP/Gel, were determined. The rod-shaped OCP/Gel was then implanted into the OVX and Sham rat tibia defects, exhibiting a similar shape and size, and assessed at 4, 8, and 12 weeks. Increasing Pi concentration in OVX-simulated buffer solution increased the DS, with respect to OCP, upon the introduction of OCP and 44% OCP/Gel, but decreased the DS to a slightly saturated condition with 17% OCP/Gel, indicating that increasing the OCP in the Gel matrix tends to inhibit the hydrolysis of OCP into hydroxyapatite (HA). Histomorphometric analyses of bone formation and the appearance of osteoblasts and osteoclast-like cells, together with OCP resorption, confirmed that while 44% OCP/Gel showed higher bone formation than 17% OCP/Gel at intramedullary bone defect sites in Sham rat tibia, both OCP/Gels tended to enhance cortical bone formation in the OVX group, concomitant with the higher resorption of OCP within 17% OCP/Gel. The appearance of osteoclast-like cells in the OVX group increased as the OCP dose decreased from 44% to 17% in the Gel matrix, with an approximately 4 times higher bone formation rate, 8-12 weeks after the implantation. Additional in vitro assays showed that bone marrow mesenchymal stem cells isolated from OVX and wild-type (WT) rats treated with OCP had similar proliferation and differentiation rates, up to 21 days. These results show that OCP can enhance cortical bone repair even in osteoporotic bone if suitable thermodynamic metastable dissolution conditions are provided in relation to the mass of OCP.

Surgical Approach to Pigmented Villonodular Synovitis and Synovial Osteochondromatosis in Pathological Expansion of the Popliteus Bursa.

We orthopaedic surgeons are not familiar with the popliteus bursa. It is defined as the expansion in the synovial membrane of the posterolateral part of the knee that lies between the lateral meniscus and the tendon of the popliteus muscle. The popliteus bursa extends approximately 1 cm distal to the joint line and has 4 borders; the medial border is the peripheral margin of the lateral meniscus, the lateral border is the popliteus tendon, and the superior and inferior borders are formed by 2 fascicles. We very rarely observe cystic lesions that expand more distally, such as pigmented villonodular synovitis (PVNS) and synovial osteochondromatosis. We consider the distally expanded bursa as the pathologic expansion of the popliteus bursa. When this expansion is involved with PVNS, it may be the cause of recurrence of PVNS in the knee joint. Synovial osteochondromatosis in this expansion may cause pain in the posterolateral corner of the knee and may become a source of free bodies in the knee joint. In such conditions, these lesions should be surgically excised. The purpose of this Technical Note is to describe a surgical approach to the pathologic expansion of the popliteus bursa.

Quality of life after staged bilateral total knee arthroplasty: a minimum five-year follow-up study of seventy-eight patients.

PURPOSE: Although many studies have been performed to evaluate the quality of life (QOL) and patient satisfaction after total knee arthroplasty (TKA), almost all evaluations were performed in patients after unilateral TKA or in patients after mixed unilateral and bilateral TKA. Accordingly, this study aimed to evaluate QOL after staged bilateral TKA. METHODS: A total of 78 patients who underwent staged bilateral TKA for varus knee osteoarthritis were included in this study. All patients had longitudinal follow-up evaluations for at least five years. QOL was assessed by the Japanese Knee Osteoarthritis Measure (JKOM), a disease-specific and patient-derived QOL measure for Japanese patients. Conventional objective outcome scales, including the Knee Society Score and the Timed Up and Go test, were also assessed. In addition, QOL and objective outcomes were compared between the younger (≤ 80 years, average 75.8 years) and older (> 80 years, average 84.7 years) age groups at the final follow-up. RESULTS: Improvements in both JKOM and objective outcomes reached a plateau one year after staged bilateral TKA. Improvements were prolonged for more than five years. There were no statistically significant differences in JKOM or objective outcomes between the younger and older age groups, despite an 8.9-year difference in the average age. CONCLUSIONS: This was the first longitudinal study to evaluate QOL and objective outcomes after staged bilateral TKA for a period of at least five years. Improvements in QOL and objective outcomes reached a plateau one year after staged bilateral TKA and were prolonged for more than five years. No significant differences were observed in outcome scores between the younger and older age groups.

The effect of morphine added to periarticular multimodal drug injection or spinal anesthesia on pain management and functional recovery after total knee arthroplasty.

BACKGROUND: The efficacy of morphine added to periarticular multimodal drug injection (PMDI) for pain management after total knee arthroplasty (TKA) is controversial. Adding morphine to spinal anesthesia has reportedly improved pain relief for the first 24 h. We examined the effect of morphine added to PMDI or spinal anesthesia on pain management and functional recovery after TKA. METHODS: A total of 97 patients were randomized into three groups: in Group A (34 patients), 10 mg morphine was added to PMDI; Group B (31 patients), 0.1 mg morphine was added to spinal anesthesia; and Group C (32 patients), morphine was added to neither the PMDI nor spinal anesthetic. To evaluate the efficacy of added morphine for pain management, we assessed rest pain, the number of times analgesics were used, and the time period until the first analgesic use. The adverse effects of morphine were assessed by counting the numbers of times vomiting occurred and antiemetics were used. Functional recovery was evaluated by recording the range of motion of the knee and the date of ability to walk. RESULTS: Rest pain was the least in Group B at 6 and 12 h after operation. The number of times analgesics were used was the least in Group B. The time period until the first analgesic use was the longest in Group B. The number of vomiting episodes was the least in Group C. The number of times antiemetics were used was higher in Group A than in Group C. There were no significant differences in the range of motion and date of ability to walk among the three groups. CONCLUSIONS: The efficacy of morphine added to PMDI was limited, and that of morphine added to spinal anesthesia disappeared within 20 h postoperatively. Adding morphine to PMDI or spinal anesthesia did not improve functional recovery and caused some adverse effects.

Evaluation of the size and position of the insertion of the anterior medial meniscus root in varus osteoarthritic knees.

PURPOSE: Recent studies have suggested radial displacement of the medial meniscus as a cause of varus knee osteoarthritis (OA). Two anatomical studies reported that such displacement may be associated with anterior insertion of the medial meniscus anterior horn. It was aimed to evaluate the location and area of this insertion in patients with advanced knee OA. METHODS: Medial meniscus anterior horn insertions were classified into four types, as described in a previously reported classification during 225 total knee arthroplasty (TKA) in 184 patients. The incidence rates of insertion type were compared with previously reported rates in nearly normal or non-arthritic knees. The insertion surface area was also measured during 158 TKAs. RESULTS: Of the 225 knees, 82 (36.4 %), 93 (41.3 %), 35 (15.6 %), and 15 (6.7 %) were classified as I, II, III, and IV, respectively. An anteriorly inserted anterior horn was not more frequent in advanced varus OA knees than in previously reported nearly normal or non-arthritic knees. The insertion surface areas were 57.5 ± 18.9, 56.1 ± 16.0, and 56.4 ± 14.4 mm2 for types I, II, and III, respectively; these areas did not differ significantly. CONCLUSION: Since the incidence of an anteriorly inserted medial meniscus anterior horn was not higher in advanced varus OA knees than in normal or non-arthritic knees, an anteriorly inserted anterior horn may have little or no effect on the aetiology of varus OA knees. This study provides some information for clarifying the aetiology of knee OA. LEVEL OF EVIDENCE: IV.

Preliminary results of managing large medial tibial defects in primary total knee arthroplasty: autogenous morcellised bone graft.

PURPOSE: This study reports a case series of 44 primary total knee arthroplasties (TKAs) using autogenous morcellised bone grafting for large (≥10-mm-deep) medial tibial defects, which are generally repaired using metal augmentation. The bone-grafting technique is described in detail and the radiological outcomes are presented. METHODS: A total of 44 TKAs were followed up for a mean period of 58 months (range 24-139 months). Multiple drill holes were made in the sclerotic floor of the defect, followed by the impaction of morcellised cancellous bone grafts to fill the defects. Tibial components were fixed using the cemented or noncemented technique and no internal fixation devices were used. Stem extension of the tibial component was only used in one TKA. RESULTS: Radiograms revealed that the grafted bone was completely incorporated into the host bone within one year post-operatively. No grafted bone absorption or collapse was detected. A clear zone between the tibial component and grafted bone was observed in six knees, but it did not become enlarged thereafter. CONCLUSIONS: The presented technique provided favourable radiological outcomes and had several advantages: (1) it enables preservation of as much bone as possible for future revision surgery; (2) it is cost effective and simple because metal augments, internal fixation devices and stem extension are not needed; (3) it can be used in the same manner any defect to a depth ≥3 mm. Thus, this is an acceptable and reproducible alternative technique.

Femoral footprint of the popliteus tendon may be at the risk of damage during total knee arthroplasty.

PURPOSE: The present study focused on the prevalence of incidental excision of the femoral footprint of the popliteus tendon during total knee arthroplasty and its associated risk factors. METHODS: A total of 275 knee arthroplasties were performed for 226 patients with varus knee osteoarthritis. The status of the femoral footprint of the popliteus tendon was intraoperatively evaluated and classified into three groups (preserved, partially excised, and completely excised), and the prevalence of the excision was identified. Femoral component size, the thickness of the resected distal femoral condyle, and preoperative patient demographic data were compared for the three groups. Ordinal logistic regression analysis was performed to reveal risk factors associated with the excision. RESULTS: The femoral footprint of the popliteus tendon was preserved in 132 knees (48.0 %), partially excised in 94 knees (34.2 %) and completely excised in 49 knees (17.8 %). The ordinal logistic regression analysis revealed thicker resection of the distal femoral condyle (p < 0.0001) and shorter body height (p = 0.0266) to be the independent risk factors for the excision. CONCLUSIONS: The incidental partial or complete excision of the femoral footprint of the popliteus tendon was identified in approximately half of the evaluated knees. Thicker resection of the distal femoral condyle and shorter body height were the most significant risk factors for the excision. LEVEL OF EVIDENCE: Case-control study, Level III.

Comparison of intraoperative anthropometric measurements of the proximal tibia and tibial component in total knee arthroplasty.

BACKGROUND: Precise matching of the tibial component and resected bony surfaces and proper rotational implanting of the tibial component are crucial for successful total knee arthroplasty. We aimed to analyze the exact anthropometric proximal tibial data of Japanese patients undergoing total knee arthroplasty and correlate the measurements with the dimensions of current total knee arthroplasty systems. METHODS: A total of 703 knees in 566 Japanese patients who underwent total knee arthroplasty for osteoarthritis were included. The bone resection in the proximal tibia was performed perpendicular to the tibial axis in the frontal plane. Measurements of the proximal tibia were intraoperatively obtained after proximal tibial preparation. RESULTS: There were significant positive correlations between the lateral anteroposterior and medial anteroposterior and mediolateral dimensions. A progressive decrease in the mediolateral/lateral anteroposterior ratio with an increasing lateral anteroposterior dimension or the mediolateral/anteroposterior ratio with an increasing anteroposterior dimension was observed. The lateral anteroposterior dimension was smaller than the medial anteroposterior dimension by a mean of 4.8 ± 2.0 mm. The proximal tibia exhibited asymmetry between the lateral and medial plateaus. A comparison of the morphological data and dimensions of the implants, one of which was a symmetric tibial component (NexGen) and the others were asymmetric (Genesis II and Persona), indicated that an asymmetric tibial component could be beneficial to maximize tibial plateau coverage. CONCLUSIONS: This study provided important reference data for designing a proper tibial component for Japanese people. The proximal tibial cut surface was asymmetric. There was wide dispersion in the lateral anteroposterior, medial anteroposterior, and mediolateral dimensions depending on the patient. Our data showed that the tibial components of the Genesis II and Persona rather than that of the NexGen may be preferable for Japanese people because of their asymmetric design.

Effect of resorption rate and osteoconductivity of biodegradable calcium phosphate materials on the acquisition of natural bone strength in the repaired bone.

The purpose of this study was to compare the biodegradation rate and quality of regenerated bone among four materials. A short time period of 8 weeks was chosen to examine early bone healing. The rod-shaped implants of commercially available two ß-tricalcium phosphate (ß-TCP) ceramics with porosity 60% and 71-80%, respectively, laboratory prepared octacalcium phosphate/gelatin composite (OCP/Gel), which has been proven to have a highly osteoconductive and biodegradable property in rat calvarial defect, and gelatin sponge (Gelatin) were implanted in rabbit tibia defect of 6 mm diameter and 7 mm depth for 2, 4 and 8 weeks. Analyses by µCT, histomorphometry and push-in test were carried out to evaluate the extent of the tissue regeneration and the material biodegradation in the long bone. OCP/Gel and Gelatin were completely resorbed but only OCP/Gel induced cortical bone bridge until 8 weeks that has strength compatible to that of the natural bone. ß-TCP (71%-80%) and ß-TCP (60%) were not completely resorbed and never induced the amount of new bone formation beyond that by OCP/Gel. The results indicate that the new bone having enough strength could be regenerated if the material shows not only higher biodegradation rate but also higher osteoconductivity. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2833-2842, 2016.

Autologous morselised bone grafting for medial tibial defects in total knee arthroplasty.

PURPOSE: To evaluate the outcome of autologous morselised bone grafting for a medial tibial defect of ≥10 mm deep in 45 total knee arthroplasties (TKAs). METHODS: 38 patients aged 46 to 85 (mean, 73) years underwent 45 TKAs and autologous morselised bone grafting for a medial tibial defect of ≥10 (range, 10-25) mm in depth by a single surgeon. In the first 19 TKAs, 2 resected subchondral bone plates from the lateral tibial plateau were driven into 2 gutters made on the floor of the medial tibial defect as bony support posts. Morselised cancellous bone grafts were then impacted around these posts. In the remaining 26 TKAs, multiple drill holes were made on the floor of the defect to decrease the remodelling time. Morselised cancellous bone grafts were impacted to fill the defects. The tibial components were fixed with cemented (n=34) or non-cemented (n=11) technique. Internal fixation devices were not used; stem extension was used in only 2 TKAs (in a patient with Charcot joint and a patient undergoing revision TKA). RESULTS: After a mean follow-up duration of 65 (range, 24-174) months, no patient showed gait disturbance. The mean knee flexion angle was 113.8º (range, 90º-130º). No absorption or collapse of the grafted bone, or component loosening were noted on radiographs. The grafted bone completely incorporated into the host bone, with bony trabeculae crossing the interface within 2 years in the first 19 TKAs and within one year in the latter 26 TKAs. The margin of the grafted area resembled bony cortex in 30 TKAs. CONCLUSION: Autologous morselised bone grafting is a viable option for most medial tibial defects during TKA.

Quality of life after bilateral total knee arthroplasty determined by a 3-year longitudinal evaluation using the Japanese knee osteoarthritis measure.

BACKGROUND: Recently, the Japanese knee osteoarthritis measure (JKOM), a new disease-specific and patient-derived quality of life (QOL) measure, has been developed. The objectives of this study were to longitudinally evaluate QOL assessed by JKOM and objective outcomes including knee society score (KSS), range of motion (ROM), and timed up and go test (TUG) of patients who underwent bilateral total knee arthroplasties (TKAs) for osteoarthritis; to evaluate correlations between JKOM and those objective outcomes; and to test our hypothesis that increased maximum flexion leads to better JKOM. METHODS: Forty patients with bilateral TKAs and ≥ 3-year follow-up were included. There were 35 female and 5 male patients with a mean patient age of 74 years. They were evaluated preoperatively (Pre), 5-29 months after unilateral TKA (after U), 12-21 months after bilateral TKAs (1 year after B), 24-34 months after bilateral TKAs (2 years after B), and 36-46 months after bilateral TKAs (3 years after B) using JKOM, KSS, TUG, and ROM. RESULTS: Improvements in JKOM and TUG were statistically significant between "Pre" and "after U", and between the "after U" and "1 year after B". Improvements in the KSS function score were statistically significant between "after U" and "1 year after B" but not between "Pre" and "after U". The improvements in the JKOM scores, the KSS function score, and TUG did not increase after the 1-year follow-up but was maintained at "3 years after B". The maximum flexion value did not change among the evaluation time points. There were statistically significant correlations between JKOM with KSS and TUG but not with ROM. CONCLUSIONS: There were statistically significant correlations between JKOM with KSS and TUG but not with ROM. Therefore, our hypothesis was false even in a Japanese population.

Effect of addition of hyaluronic acids on the osteoconductivity and biodegradability of synthetic octacalcium phosphate.

The present study was designed to investigate whether three sodium hyaluronic acid (HyA) medical products, Artz(®), Suvenyl(®) and a chemically modified derivative of sodium HyA Synvisc(®), can be used as suitable vehicles for an osteoconductive octacalcium phosphate (OCP). OCP granules (300-500 µm diameter) were mixed with these sodium HyAs with molecular weights of 90 × 10(4) (Artz(®)), 190 × 10(4) (Suvenyl(®)) and 600 × 10(4) (Synvisc(®)) (referred to as HyA90, HyA190 and HyA600, respectively). OCP-HyA composites were injected using a syringe into a polytetrafluoroethylene ring, placed on the subperiosteal region of mouse calvaria for 3 and 6 weeks, and then bone formation was assessed by histomorphometry. The capacity of the HyAs for osteoclast formation from RAW264 cells with RANKL was examined by TRAP staining in vitro. Bone formation was enhanced by the OCP composites with HyA90 and HyA600, compared to OCP alone, through enhanced osteoclastic resorption of OCP. HyA90 and HyA600 facilitated in vitro osteoclast formation. The results suggest that the osteoconductive property of OCP was accelerated by the HyAs-associated osteoclastic resorption of OCP, and therefore that HyA/OCP composites are attractive bone substitutes which are injectable and bioactive materials.

Incidental durotomy during lumbar spine surgery: risk factors and anatomic locations: clinical article.

OBJECT: Incidental durotomy (dural tear) is a common complication of lumbar spine surgery. The purpose of this study was to clarify the anatomical location of and the specific causative factors for incidental durotomy during primary lumbar spine surgery. METHODS: The authors retrospectively reviewed 1014 consecutive cases involving patients (412 women and 602 men; mean age 57 years; age range 11-97 years) who underwent a surgical procedure for treatment of degenerative lumbar spinal disease at their institution between 2002 and 2008. In total, 1261 disc levels were treated surgically. Disease at the treated levels included 544 disc herniations, 453 instances of spinal canal stenosis without spondylolisthesis, 188 instances of lumbar spinal canal stenosis with spondylolisthesis (degenerative spondylolisthesis), 49 instances of combined stenosis (stenosis with disc herniation), and 22 juxtafacet cysts. In 5 of the treated levels, the condition was classified as "other" disease. Treatment included fenestration with discectomy in 547 levels, fenestration alone in 626, fenestration with resection of juxtafacet cysts in 22, unilateral recapping laminoplasty in 20, posterolateral spinal fusion or posterior lumbar interbody fusion in 17, microscopic discectomy with tubular retractor in 14, and "other" in 15. RESULTS: Unintended durotomy occurred in 4% of cases and in 3.3% of disc levels. The incidence of dural tear was significantly higher in women (5.6%) than in men (3%). The incidence of dural tear was 2% in disc levels with lumbar disc herniation, 1.8% with lumbar spinal canal stenosis without spondylolisthesis, 9% with degenerative spondylolisthesis, and 18.2% with juxtafacet cysts; the incidence was significantly higher in levels with degenerative spondylolisthesis or levels with juxtafacet cysts, than in those with other diseases. Incidental durotomy occurred in 4 critical anatomical zones, namely, the caudal margin of the cranial lamina, cranial margin of the caudal lamina, herniated disc level, and medial aspect of the facet joint adjacent to the insertion of the hypertrophic ligamentum flavum. CONCLUSIONS: Risk factors for unintended durotomy were female sex, older age, degenerative spondylolisthesis, and juxtafacet cysts. In this study, the authors identified 4 high-risk anatomical zones that spine surgeons should be aware of to avoid dural tears.

Mechanical stress-related calvaria bone augmentation by onlayed octacalcium phosphate-collagen implant.

Previous studies have suggested that the biodegradability of octacalcium phosphate-collagen (OCP/Col) composite by osteoclasts is accelerated in association with mechanical stress suffered by the host tissue around the implant. The present study was designed to investigate whether alleviation of mechanical stress restores the bone regenerative properties of OCP/Col, as previously shown in nonload-bearing sites. OCP/Col discs supported with a polytetrafluoroethylene (PTFE) ring, which has a higher modulus than OCP/Col, were implanted in a rat subperiosteal pocket for up to 12 weeks. The structural features of the implant and biological responses were analyzed by X-ray diffraction, Fourier transform infrared spectroscopy, histomorphometry, histochemistry, and tissue mRNA expression around the implants. The effect of compression was analyzed using mouse stromal ST-2 cells by deforming the cell-seeded OCP/Col discs in vitro with or without a PTFE ring. The results clearly indicated the restoration of bone formation by the alleviation of mechanical stress and the upregulation of osteoblast-related genes, such as osterix on the other hand, the implantation of OCP/Col on calvaria or in an in vitro test without PTFE support resulted in the upregulation of osteoclast-related genes, such as tartrate-resistant acid phosphatase (TRAP) and cathepsin K, in the tissues or receptor activator of the nuclear factor-kappaB ligand (RANKL) in ST-2 cells. The results confirmed that calvaria augmentation is enhanced by implanting OCP/Col if suitable conditions regarding mechanical stress are provided.

Effect of partial hydrolysis of octacalcium phosphate on its osteoconductive characteristics.

The present study was designed to investigate whether the stoichiometry of octacalcium phosphate OCP affects its osteoconductive and immune response characteristics in rat bone marrow. Those characteristics of synthetic, well-grown OCP but with a non-stoichiometric composition were compared with those of a slightly hydrolyzed OCP (low crystalline OCP: LC-OCP), the fully hydrolyzed apatitic product of OCP or biodegradable beta-tricalcium phosphate (beta-TCP) ceramic, by their implantation in rat tibia for 56 days. The physicochemical aspect of implants and biological responses were analyzed by X-ray diffraction, histomorphometry, immunohistochemistry and expression of mRNA around the implants. The remarkable findings were that: (1) the highest bone formation rate was obtained for beta-TCP whereas the lowest for LC-OCP at Day 14; (2) the rates were reversed and reached the highest for LC-OCP until Day 56; (3) the early expression of ostoeoclast markers TRAP and cathepsin-K was suppressed with LC-OCP; (4) the expression of inflammatory markers IL-beta1 and TNF-alpha was suppressed with LC-OCP. The results confirmed that the partially hydrolyzed OCP with Ca/P molar ratio 1.37 (LC-OCP) enhances bone formation most, suppressing early osteoclast activity and reducing inflammation.