Objective: In 2017, the substitute anteroposterior (sAP) line connecting the medial border of the patellar tendon at the articular surface level and the medial intercondylar tubercle was proposed for an AP reference in medial unicompartmental knee arthroplasty (UKA) and shown to be almost perpendicular to the surgical epicondylar axis (SEA). However, the AP alignment of the components implanted using this line in actual UKA procedures has not been known.

Methods: Postoperative computed tomography datasets from 60 lower limbs in 60 Japanese patients underwent fixed-type medial UKA, including 30 limbs using sAP line as AP reference and 30 limbs using medial intercondylar ridge (MIR), were used. First, the angles between the SEA and AP directions of the tibial and the femoral components were measured. Next, the anteroposterior rotational mismatch angles between the tibial and femoral components were measured.

Results: The tibial and femoral components implanted using sAP line were externally rotated 90.6°±3.4° and 92.1°±7.9° relative to the SEA, respectively; using MIR were 95.1°±8.5° and 91.1°±7.6°, respectively. The externally rotation angle of the femoral component relative to the tibial component when using sAP line and MIR as AP reference was 0.3°±8.7° and −3.9°±6.8°, respectively.

Conclusion: Using sAP line as the AP reference in medial UKA procedures makes it possible to implant the tibial component almost perpendicular to the SEA and to reduce the rotational mismatching between the femoral and tibial components.

Objective: Total knee arthroplasty is performed for severe valgus deformity of the knee due to rheumatoid arthritis. When this type of deformity is present, resection of the posterior cruciate ligament (PCL) and implantation of a posterior stabilized (PS) prosthesis are commonly performed.

 We used to employ a PS prosthesis as the first choice. However, we have preserved the PCL and used a cruciate retaining (CR) prosthesis to maintain the bone stock since January 2008. In this study, we reviewed the outcome of TKA for severe valgus deformity of the knee in RA patients with a femorotibial angle (FTA) ≤160°. In addition, we evaluated the usefulness of the CR prosthesis.

Patients and Methods: Twenty female patients (20 joints) with a femoral-tibial angle (FTA) ≤160° and a mean age of 58.4 years at the time of surgery were included in this study. Eighteen patients had a Krackow Type Ⅰ knee and 2 patients had a Krackow Type Ⅱ knee. All operations were performed via the midvastus approach, using a CR prosthesis in 9 joints and a PS prosthesis in 11 joints. The mean follow-up time was 8 years and 10 months.

 Statistical analysis was conducted using the Wilcoxon signed ranked test, Mann-Whitney U-test, and Fisher’s exact test (extended). P<0.05 was judged as statistically significant.

Results: The JOA score was 44.2 before surgery and 89.8 at the time of examination, while the FTA was 155.9° and 175.4°, respectively, with both parameters showing significant improvement. No patient underwent revision surgery for instability. Comparison of the clinical evaluation and plain X-ray findings at the time of examination, before surgery, and at the operation revealed no significant changes between the two types of prosthesis (CR vs. PS).

Conclusion: These results suggest that a CR prosthesis can be selected for TKA to treat severe valgus deformity of the knee in RA patients, provided the patient has a Krackow Type Ⅰ knee and a functioning PCL.

Objective: The efficacy of platelet-rich plasma (PRP) injections for knee osteoarthritis (OA) is often reported, despite parameters closely correlated with symptomatic relief not being definitely established. We assessed correlations between symptomatic relief induced by PRP and five parameters.

Methods: Thirty-nine patients with knee OA were treated with PRP. A 6.0-ml sample of an autologous leukocyte-reduced PRP was obtained from 40 mL of whole blood by Cell Source Co. Ltd. Two intra-articular injections of this PRP were given at a 2-week interval. The following five parameters were evaluated: age, disease duration, body mass index (BMI), radiographic femorotibial angle (FTA) and the protrusion of the medial meniscus with displacement of the medial collateral ligament (meniscal protrusion) as seen on the ultrasound screen.

The improvement rate was calculated by dividing the difference between 12 week assessment and baseline scores of the Lequesne index by the baseline score and multiplying by 100.

Results: All patients returned for the final follow-up visit. Percent remission was not significantly correlated with age, disease duration, BMI and FTA (P>0.05). The correlation between meniscal protrusion and improvement rate was significant (P=0.026, R=0.36).

Conclusion: In the current study, improvement rate induced by PRP decreased with increase of meniscal protrusion. The correlation suggested that patients with knee OA who had less meniscal protrusion could expect good improvement from intra-articular injections of PRP.

Objective: Total hip arthroplasty (THA) is an established and excellent treatment for the painful hip. Despite good results, some patients are suffering from complications. Thigh pain is one of the complications after THA. The incidence of thigh pain after THA has not been clarified yet. The purpose of this study was to investigate clinical and radiographic factors that affect the incidence of thigh pain one year after THA.

Methods: Evaluation was performed in consecutive 89 hips (76 patients) who underwent THA from May 2015 to May 2017. Presence of thigh pain was recorded at regular follow up one year after surgery. Any complaints of the pain around the target hip joint and ipsilateral femur were recorded as thigh pain. To clarify the incidence of thigh pain, clinical features, radiographic parameters (canal filling ratio, cortical hypertrophy, cortical index, canal flare index, leg length discrepancy (LLD), femoral offset) and implant size were evaluated. These clinical features and other measured values were compared between the patients group complained thigh pain to the group without thigh pain after surgery.

Results: 27 joints had thigh pain within one year after surgery. Among them 6 joints had thigh pain one year after surgery (TP1 group). 21 joints had transient thigh pain (TP0 group). Other 62 joints had no thigh pain after surgery (N group). There were 6 stovepipe shape femurs which had no thigh pain after surgery. The mean LLD of the TP1 group was −2.5 mm before surgery. This was significantly less than the LLD values of the other two groups before surgery. The femoral offset of TP1 group patients decreased 4.1 mm on average after THA. This decrease was significant compare to the change of the femoral offset in the other two groups.

Conclusion: A decrease in the femoral offset may affect the incidence of thigh pain after THA. Therefore, it is better for the surgeon not to decrease femoral offset during surgery. Also, the LLD before surgery and the shape of the femur may affect the incidence of thigh pain after THA.

Objective: The purpose of this study is to discuss the results of revision total elbow arthroplasty for rheumatoid arthritis patients.

Methods: We investigated clinical outcomes and complications for 10 patients with rheumatoid arthritis who were treated for revision total elbow arthroplasty from 1999 to 2015 (mean of age 59.1±13.2 years old, all female). We compared JOA scores and range of motion between linked type and unlinked type.

Results: The results of revision total elbow arthroplasty were 5 loosenings, 3 instabilities, one dislocation fragment occurred intra-operation, and one fracture after operation. The duration from first operation to second operation was 5 years 7 months. Products of primary TEA were 6 Kudo Elbow, 2 JACE, one Stable Elbow and one Souter Strathyclyde. The products of revision TEA were 5 Coonrad Morrey, 3 Kudo Elbow, and 2 Stable Elbow. The number of unlinked types was equal to the number of linked types. The JOA score of the linked type improved from 59.6±9.0 pre-operation to 81.6±3.8 post-operation (P<0.05). On the other hand, the JOA scores of the unlinked type improved from 36.0±10.2 pre-operation to 64.6±9.0 (P<0.05). Both JOA scores of the unlinked type and of the linked type improved about pain, instability significantly, and range of motion decreased. The range of motion of the linked type changed and flexion and extension improved. On the other hand, in the unlinked type, flexion improved and pronation went down.

 The 5 year survival rate of unlinked type and of linked type was both 100%.

Conclusion: We investigated the results of revision TEA between the unlinked type and the linked type. The 5 year survival rate was not different and both JOA scores improved.

 The quadriceps tendon is strong, and the subcutaneous tear is a rare disease in the knee extensor mechanism injury. We experienced 3 cases in middle-aged men who were performed surgery by the pull-out method reattached to the proximal portion of the patella.

Case 1: Sliding in a puddle while walking, and falling forward when standing with the left knee. Operation was done at 10 days after the injury.

Case 2: Fallen by stairs. sliding down in a state of the sitting straight. Operation was done at 5 weeks after the injury.

Case 3: Injured in going down the stairs in a drunkenness state. Operation was done at 10 days after the injury.

 In all cases, after surgery over six months, the range of knee motion was full without extension lag.

 As a diagnosis was late in case 2, this disease is sometimes easily ignored because of lacking the characteristic views on the X-rays. The most important point to diagnose precisely this disease is that a physician do careful clinical examination.

Introduction: Staphylococcus aureus and Streptococcus species cause knee arthritis; however, there are very few reports of knee arthritis caused by Neisseria gonorrhea infection. Here, I report a case of purulent knee arthritis caused by multidrug-resistant N. gonorrhea infection.

Case: A 55-year-old male with diabetes mellitus and a BMI of 25.8 kg/m² visited our hospital. He complained of pain in his left knee joint and left wrist. His body temperature was 38°C; moreover, he had tenderness, swelling with heat emanating from his left hand joint and left knee joint, and rush on the entire surface of the limbs. He had a diffused inflammatory response along with a white blood cell count of 18520/μL and CRP level of 11.0 mg/dL. Additionally, his blood sugar level was 459 mg/dL and HbA1c level was 10.6%; his diabetes was poorly controlled. We performed a joint puncture after examining left floating patella. The synovial fluid was yellowish white and slightly opaque, with a sugar level of 364 mg/dL and the presence of many white blood cells. However, microscopic examination failed to reveal crystals and bacteria in the synovial fluid. Because we considered the possibility of knee arthritis, we performed arthroscopic debridement. Subsequently, synovial fluid culture was performed, and penicillinase-producing N. gonorrhea (PPNG) was detected on the fifth day. Thus, we initiated intravenous ceftriaxone administration. By postoperative day 17, his inflammatory reaction and symptoms improved.

Discussion: Reportedly, PPNG accounts for a small percentage of gonococci in Japan. Early arthroscopic debridement, which is recommended for general knee arthritis, proved effective against PPNG.

Conclusion: We reported a case of knee arthritis caused by multidrug-resistant N. gonorrhea.