Takaji Yanai

Joint distraction and movement for repair of articular cartilage in a rabbit model with subsequent weight-bearing

We have previously shown that joint distraction and movement with a hinged external fixation device for 12 weeks was useful for repairing a large articular cartilage defect in a rabbit model. We have now investigated the results after six months and one year. The device was applied to 16 rabbits who underwent resection of the articular cartilage and subchondral bone from the entire tibial plateau. In group A (nine rabbits) the device was applied for six months. In group B (seven rabbits) it was in place for six months, after which it was removed and the animals were allowed to move freely for an additional six months. The cartilage remained sound in all rabbits. The areas of type II collagen-positive staining and repaired soft tissue were larger in group B than in group A. These findings provide evidence of long-term persistence of repaired cartilage with this technique and that weight-bearing has a positive effect on the quality of the cartilage.

Effect of gradual weight-bearing on regenerated articular cartilage after joint distraction and motion in a rabbit model.

The purpose of this study was to clarify the effect of gradual weight bearing (GWB) on regenerating cartilage. We developed a novel external fixation device (EFD) with a controllable weight‐bearing system and continuous passive motion (CPM). A full‐thickness defect was created by resection of the entire articular surface of the tibial plateau after the EFD was fixed in the rabbits left knee. In the GWB group (n = 6), GWB was started 6 weeks after surgery. In the CPM group (n = 6), CPM with EFD was applied in the same manner without GWB. The control group (n = 5) received only joint distraction. All rabbits were sacrificed 9 weeks after surgery. The central one‐third of the regenerated tissue was assessed and scored blindly using a grading scale modified from the International Cartilage Repair Society visual histological assessment scale. The areas stained by Safranin‐O and type II collagen antibody were measured, and the percentage of each area was calculated. There was no significant difference in the histological assessment scale among the groups. The percentage of the type II collagen‐positive area was significantly larger in the GWB group than in the CPM group. The present study suggests that optimal mechanical stress, such as GWB, may affect regeneration of cartilage, in vivo.

Immunohistochemical Demonstration of Cyclooxygenase-2 in Glomus Tumors

BACKGROUND Glomus tumors are benign hamartomas that account for 1% to 5% of all soft-tissue tumors of the hand. Painful spasms radiating from the lesion are typical clinical signs. As the pain production mechanism is unclear, we evaluated S100 protein, substance P, and cyclooxygenase-2 expression by immunohistochemistry in glomus tumor samples. METHODS Eight solitary glomus tumors were surgically excised and confirmed histologically by an experienced pathologist. Paraffin-embedded tissues were prepared for immunohistochemistry. The sections were stained with separate polyclonal antibodies for S100, substance P, and cyclooxygenase-2. In three of the tumors, we measured the prostaglandin E2 concentrations. RESULTS All samples were positive for S100 protein and cyclooxygenase-2.Substance P was found in five of the eight samples. High prostaglandin-E2 concentrations were seen in all three samples tested. CONCLUSIONS Cyclooxygenase-2-immunoreactive cells are present in solitary glomus tumors. Since cyclooxygenase-2 produces prostaglandin E2, which is thought to be a strong vasodilator, the pain could be caused by vasodilation in the glomus tumor, with increased intracapsular pressure.

Disruption of Flexor Tendon after Intrasheath Triamcinolone Acetonide Injection for Trigger Digits: Two Case Reports

We experienced two cases of flexor tendons rupture after triamcinolone acetate (TA) injection for trigger finger. A 45-year-old man underwent injection of 40 mg of TA and 1 mL of 1% lidocaine solution into his little finger. While playing golf 3 months after the injection, he heard a popping sound, and was unable to flex it. A 57-year-old female nurse had undergone injection of 40 mg of TA and 1 mL of 1% lidocaine solution into her thumb twice at a 2-month interval. Two months after the second injection, she was unable to flex it. Both cases had high concentrated TA injection at trigger digits. The present and previous cases illustrate that when TA is injected into trigger digits, the dose should be low, the safety interval should be long, and refuse injection into the tendon proper.

Lipofibromatous Hamartoma of the Median and Ulnar Nerves at the Ipsilateral Wrist

Lipofibromatous hamartoma (LFH) is a rare condition of the peripheral nerves that typically affects the median nerve. To the best of our knowledge, this is the first report of LFH of both, the median and ulnar nerves, at the wrist of a 63-year-old female patient. The patient presented to our hospital with a 40-year history of pain, numbness, and dysesthesia affecting all fingers of her left hand. Atrophy of the thenar muscles and the first dorsal interosseous was observed upon physical examination. Imaging studies and a surgery revealed that the patients median and ulnar nerves were significantly enlarged, confirming the LFH diagnosis. The patients dysesthesia and numbness improved after Carpal tunnel and Guyon canal release, and her pinch ability improved after opponensplasty. LFH has been known to be solitary, typically affecting median nerve, but it must be noted that the tumor may affect multiple nerves like in our case.

Fabella Syndrome as an Uncommon Cause of Posterolateral Knee Pain after Total Knee Arthroplasty: A Case Report and Review of the Literature

The fabella is a sesamoid bone that is located in the lateral head of the gastrocnemius muscle and has been identified on magnetic resonance imaging in 31% of Japanese people. In the present case, a 65-year-old woman experienced posterolateral knee pain, accompanied by a clicking “sound” during active knee flexion, after undergoing total knee arthroplasty for knee osteoarthritis. Eight months of conservative therapy failed to produce an improvement, with progressive osteoarthritic change of the fabella identified on plain radiography. Based on this evidence, a diagnosis of fabella syndrome was made and the patient underwent a fabellectomy. Fabellectomy provided immediate resolution of posterolateral knee pain and the clicking sound with knee flexion, with the patient remaining symptom-free 18 months after fabellectomy and with no limitations in knee function. Fabellectomy eliminated symptoms in all of five case reports that have been previously published and is regarded as an effective first choice for treating fabella syndrome after total knee arthroplasty.