Introduction

We have investigated the long-term (minimum follow-up period; 10 years) clinical results of the total hip arthroplasty (THA) using K-MAX HS-3 tapered stem.

Introduction

We have compared the middle-term (average follow-up period; 10 years) clinical results of the K-MAX HS-3 tapered stem with those of the previous type having cylindrical tip.

Introduction

IBBC (interfacial bioactive bone cement method, Oonishi) (1) is an excellent technique for augmenting cement-bone fixation in the long term. However, the technique is difficult and there are concerns over some points, such as bleeding control, disturbance of cement intrusion to anchoring holes by granules, difficulty of the uniform granular dispersion to the acetabular bone (Zone 1 in particular). To improve this technique, we have modified IBBC (M-IBBC), and investigated the short-term clinical results and radiographic changes.

Purpose

We have compared the short-term clinical results of total hip arthroplasty (THA) using PMMA bone cement and hydroxyapatite (HA) granules (interfacial bioactive bone cement method; IBBC) with the results of conventional method using PMMA bone cement.

Introduction: Preoperative planning is an important issue for total hip arthroplasty (THA). We normally use a traditional handwritten method with X-ray and two-dimensional (2-D) template. This method is simple and easy to plan the THA. However the 2-D planning is not accurately analyzed for especially DDH or severe deformity. New three-dimensional (3-D) preoperative planning software (ATHENA, Soft Cube) was developed for total knee replacement. The method of this software is based on roentogen stereophotogrammetoric analysis (RSA). The software can superimpose the 3-D CT and the prosthetic CAD model onto 2 X-rays. We hypothesized that this software would improve the accuracy of preoperative THA planning compared to the 2-D planning.

Materials and Methods: Fifty patients (male/female = 2/48) underwent THA using cementless stem and cementless acetabular component. Preoperatively, two different planning Methods: were done for all hips. The conventional 2-D handwritten planning was done with a template of the total hip system based on a standard AP X-ray of the hip (Group 1). Each patient had 2 directions X-ray with a particular marker and CT around only hip. The software calculated the source position of X-ray in each view by the marker and the angle between 2 X-rays based on RSA. The software superimposed the 3-D CT hip model and the proper size prosthetic CAD model onto 2 X-rays (Group 2).

Results: The acetabular component implanted was the same as that planned in 78% (Group 1) and 90% (Group2). The stem implanted was the same as that planned in 38% (Group 1) and 68% (Group2). The stem planning with the software improved significantly compared to the 2-D templating (P< 0.05, Chi-square for independence test).

Discussion and Conclusions: CT based computer preoperative planning was introduced to improve the accuracy of THA planning and reported good results in recent years. However the CT based method depends on high quality CT and cannot use effectively X-ray. This 3-D preoperative planning software can synchronize both digital X-ray and CT and define proper 3-D space. The software corrects the CAD model’s angles such as ante-version and torsional abnormalities accurately and easily in the same space. We can confirm those data simultaneously and get a lot of accurate information before the surgery. This method improves the accuracy of THA.

Introduction: This study prospectively measured fifty consecutive patients who had the preoperative diagnosis of osteoarthritis undergoing total knee arthroplasty (TKA) to evaluate the change of the bone mineral density (BMD) of the calcaneus.

Materials & Methods: Broadband ultrasound attenuation through the calcaneus was measured to assess the BMD of patients. The BMD was measured preoperatively and 1 month (M), 3M, 6M, 1 year, and 2 years after TKA.

Results: The mean BUA at each stage was 47.1, 45.8, 46.7, 46.7, 47.8 and 53.1, respectively. During the first 6 months, the BUA declined inconsistently in most patients, but by 1 year, the BUA recovered to the initial BUA before surgery and by 2 years, the BUA increased than the initial BUA, although there ware not satisfactory different. Despite a predicted age-related loss of 4% during 2 years, 78% of the calcaneus on the operative side had BMD higher than preoperative levels and 85% had BMD that was within the expected 4% age-related loss.

Discussion: These results indicated that TKA might contribute to decrease the age-related BMD loss. The increase with TKA in patient mobility and the increased heel loading may be a mechanism whereby the calcaneus BMD increases.

Conclusion: It is very important for surgeons to recognize the objection beneficial effects of TKA in addition to pain relief.

Introduction: The purpose of this study is to determine in vivo femorotibial axial rotation magnitudes and patterns in mobile-bearing posterior stabilized total knee arthroplasty (PS-TKA) and unicondylar knee arthroplasty (UKA) in deep flexion.

Material and Methods: Using video fluoroscopy, 12 subjects having a mobile-bearing PS-TKA (NexGen LPS Flex) and 12 subjects having a mobile-bearing UKA (Oxford UNI) were analyzed to determine their in vivo kinematic patterns under both weight bearing and non weight bearing. All implants were implanted by the same surgeon and were judged successful clinically with no pain and ligament laxity. The femoral and tibial components were overlaid onto the fluoroscopic images using a three-dimensional automated model-fitting technique to determine joint mobility.

Results: The average range of motion was 124 degrees of flexion for the PS-TKA and 137 degrees of flexion for the UKA. Although subjects in this study exhibited variable motion pattern, the common is anterior movement in extension to 45 degrees of flexion and posterior movement in 60 degrees of flexion to full flexion. The average internal rotation of the tibia was 18 degrees in UKA and 6 degrees in PS-TKA at 100 degrees of flexion to full. Incidence of lateral condylar lift off greater than 2mm was 5 in the PS-TKA and 1 in the UKA.

Discussion: A medial pivot kinematic pattern was observed in deep flexion in UKA. However in extension to 45 or 60 degrees of flexion, anterior condylar movement was observed in both groups. The motion pattern of UKA in 60 degree of flexion to full was close to the natural knee motion.

This study reports the comparison of the clinical use of a new tourniquet system for total knee arthroplasty that can determine its pressure in synchrony with systolic blood pressure (SBP) with the conventional that keeps the initial setting pressure. We prospectively applied the additional pressure of 100 mmHg based on the SBP recorded prior to skin incision to consecutive 72 procedures (conventional; initial 36, new; following 36). Six knees with the conventional and none of 5 with the new showed oozing blood in surgical field after sharp rise in SBP. According to statistically no difference of the perioperative blood loss without any tourniquet-related postoperative complications in both groups, the new system seemed to be much practical device especially for controlling a bloodless surgical field.

Suggestions for improved wear performance of total knee replacements have included replacement of standard CoCr femoral components with ceramic. Yttria-stabilized zirconia (y-TZP) was introduced as high-strength and high toughness ceramic as an alternative to alumina ceramic. Since the introduction of zirconia in 1985, the clinical outcomes and successes for hip joint have been controversial. Y-TZP ceramics have been studied both experimentally and clinically. Magnesia-stabilized zirconia (Mg-PSZ) also appears promising for total knee replacements (TKR).

Mg-ZrO2 and CoCr femoral condyles were compared in the VanguardTM knee configuration (Biomet Inc, IN). Molded tibial inserts (GUR1050) were gamma-irradiation sterilization to 3.2-Mrad under argon. Knee simulation was conducted on a 6 station simulator (Shore Western Manufacturing, Monrovia, CA). Motion included 20 degrees of flexion/extension, 5 degrees of internal/external rotation and 5 mm of AP-translation. All knee components were subjected to 6 million cycles of normal walking (2.9 kN max, freq 1.4 Hz). Lubricant was 50% alfa-calf serum diluted to 20 mg/ml protein and using EDTA additive. Test duration was 6 million cycles (6-Mc), and wear was measured by weight-loss techniques.

For wear trending of CoCr/PE and MGZ/PE, linear wear trends were apparent from 1 to 6 Mc test duration. The control implants (CoCr/PE) showed excellent linear trending (regression coeff r> 0.99) with wears rate averaging 6.3 mm3/Mc. These data showed good control of experimental variance (< 10%). The ZrO2/PE combination showed good linear trending (r > 0.86) with wear rate averaging only 0.8 mm3/Mc. This set also showed good control of experimental variance (< 15%. The MGZ/PE wear was 8-fold reduced from that of CoCr/PE.

The laboratory knee wear simulation appeared very supportive of femoral condyles of Mg-stabilized zirconia. Such implants may provide excellent performance for active patients who may risk high wear rates over many years of use.

A randomized, prospective stress arthrometric study was done on 60 knees in 60 patients, using a Telos arthrometer to determine the changes of varus-valgus laxity with time and to evaluate the relationship between laxity and retention of posterior cruciate ligament (PCL) using mobile bearing prostheses.

Thirty knees had PCL -retaining (PCLR) with an average 75 months follow-up (range; 60–106 months) and 30 had PCL-sacrificing (PCLS) prostheses with an average 78 months (range; 60–109 months). In all patients, the preoperative diagnosis was osteoarthritis. The coronal conformity of the PCLR and PCLS designs was similar. All of the TKA procedures were judged clinically successful (Hospital for Special Surgery scores: PCLR 92 ±4 points, PCLS 92 ±3 points). The patients had no clinical complications. Varus-valgus laxity was measured with the knee in extension at 6 months, 1 year, 2 year and 5 year after surgery. The intrasubject error was less than 1 degree.

Laxity with PCLR at 6 months, 1, 2 and 5 years was 3.7, 4.0, 4.1, 4.2 degrees with varus, 3.5, 3.5, 3.5, 3.6 degrees with valgus laxity. Laxity with PCLS was 4.3, 4.3, 4.3, 4.4 degrees with varus, 3.7, 3.4, 3.5, 3.6 degrees with valgus laxity. The changes of the varus and valgus laxity had no significant differences in both PCLR and PCLS groups using a repeated measure ANOVA methods (p> 0.05).

The coronal laxity has proved to be no changes with time for the patients who have clinical good results. The changes of the varus-valgus laxity for long timehad no significant differences in both PCLR and PCLS groups. Therefore, we conclude that the PCL doesn’t affect coronal stability in Extension and that the characteristics of the component geometry may act as a resistance factor. We surgeons should have a new understanding of the importance to obtain the balanced coronal laxity for successful mobile-bearing TKA for long period.

In this prospectively randomized study, we compared the changes in the range of motion (ROM) in posterior cruciate ligament-retaining (PCLR) (n=50) and -sacrificing (PCLS) (n=50) total knee arthroplasties during the perioperative period. The median ROM in PCLR prostheses was 122.5° preoperatively, 120.0° intraoperatively, and 100.0° at discharge, and 115.0°, 120.0°, and 95.0°, respectively, in PCLS. The designs did not differ statistically in each period (p> 0.05). Both designs showed significant correlations between the preoperative and intraoperative ROM, and between the preoperative and discharge ROM. Only the PCLS showed a significant correlation between the intraoperative and discharge ROM. Since the PCL tenses with flexion, the degree of preoperative degeneration, intraoperative recession, and postoperative tension of the PCL may have played a major role in the results. The PCLS design has an advantage in rehabilitation planning because of the predictable changes in the ROM during the perioperative period, although the acquired average ROM at discharge did not differ statistically.

We investigated clinical features and surgical outcomes for compressive cervical myelopathy in patients over 75 years of age.

Twenty-one patients who underwent surgical decompression for cervical myelopathy were reviewed. The average age at the time of operation was 78.0 years and the mean follow-up period was 5.7 years. Posterior decompression in 19 patients and anterior decompression in 2 patients were performed. Neurologic deficits before and after surgery were assessed using a scoring system by the Japanese Orthopaedic Association (JOA score). Radiological features were examined with radiographs and MRI. The clinical results were compared to those of 24 control patients who were less than 65 years of age at the time of surgery. The average age was 50.2 years and the mean follow-up period was 4.5 years.

In the aged patients, the preoperative mean JOA score was 6.2. Radiological examination revealed that the spinal cord was multisegmentally impinged. The postoperative maximum JOA score averaged 11.1, and the recovery rate was 45.4%. All patients became ambulatory and independent in fundamental daily activities following surgery. Maximum recovery was obtained from 1 to 3 years after the operation and function was maintained for at least 3 years. At the final follow up, the mean JOA score had been reduced to 9.5 and the recovery rate to 27.4%. Only the preoperative duration of symptoms correlated with the outcomes. The pre-operative JOA score in the control patients was 6.5. The postoperative maximum JOA score was 13.8 and the recovery rate was 69.4%. This was not significantly changed at the final follow-up.

Although postoperative recovery of function was significantly inferior to that of the control patients, surgical treatment appears to be beneficial, even in patients over 75 years of age, in improving neurological function and ability of activities in daily living.

Yachting is dangerous sport due to weather conditions. But, before this study, no data was available in the medical literature on yachting injuries. We undertook this study to analyze the yachting injury mechanism and to make inquires about this prevention. The players were asked about the details of yachting injuries they had experienced, in a questionnaire. 114 players (40.6%) out of 281 responded to the questionnaire. 35 players had experienced at least one injury (30.7%). Injury incidence of 470 class (66.7%) was significantly higher of other class; snipe38%, sea hopper 23%, FJ 22% (P< 0.05). Heads and faces were involved in 30.8% of the injuries, and upper and lower extremities in 26.8%. 44% of injury mechanism is attributed to free running injuries, which occurred during a Gybing or wild Gybing predominantly. The boom was part of the yacht which most commonly caused injury, followed by the sheet, side stay, spinnaker pole. We concluded that advancement of performance level, protection equipment, and proper judgement about weather conditions were necessary to prevent these yachting injuries.