Aims

Myokine developmental endothelial locus-1 (DEL-1) has been documented to alleviate inflammation and endoplasmic reticulum (ER) stress in various cell types. However, the effects of DEL-1 on inflammation, ER stress, and apoptosis in tenocytes remain unclear.

Purpose

Failure resulting from a recurrent infection in total knee arthroplasty (TKA) is a challenging problem. Knee arthrodesis is one treatment option, however fusion is not always successful, as there is huge bone defect. The authors reports a new arthrodesis technique that uses a bundle of flexible intramedullary rods and an antibiotic-loaded cement spacer.

Purpose

Most of revision TKA needs bone reconstruction. The success of revision TKA depends on how well the bone reconstruction can be done. The method of reconstruction includes bone cementing, metal augmentation, allogenic bone graft, APC and tumor prosthesis, etc.

In moderate to severe bone defect, allograft is needed. However, allogenic bone graft is surgically demanding and needs long operation time, which is very risky to the elderly patients. The authors revised an alternative method of bone defect reconstruction using cementing method with multiple screws augmentation.

Introduction

The bone defect reconstruction is the first step of successful primary or revision TKA in case of large bone defect. If the defect is not reconstructed adequately, we can neither preserve knee joint function nor guarantee long survival of the implant. Allogeneic bone graft is known to be the treatment of choice in large defect. However the surgical technique is demanding and incorporation failure is constant issue of the allogeneic bone graft. We propose new bone defect reconstruction technique using multiple screws and cement.

Revision of infected TKA is one of the most challenging operation as the surgeon should achieve two goals, ie eradication of infection and restoration of function.

For the eradication of infection, a minimum of two operations are needed in most of cases.

First stage of revision is meticulous debridement and insertion of antibiotic loaded cement.

During arthrotomy, thick fibrous and granulation tissues which is located in the suprapatella pouch, lateral site to the patella tendon and posterior joint space should be removed so as to get better exposure, to get rid of infection source and to get better functional result.

During debridement, I use highly concentrated antibiotic saline (1 gm vancomycin in 10cc saline), for irrigation of the operation field. I also pack the opening of the medullary canal so as to prevent the debris from entering into the medullary canal.

I use antibiotics with the ratio of 1:3.

To reduce the dead space in the medullary canal I insert a dowel shaped antibiotic loaded cement spacer made from one pack of cement and fill the medullary canal. Thereafter two packs of cement are used to make a block to fill the gap between femur and tibia. The cement block should be large enough to cover the distal femur and proximal tibia so as not to cause bone defect and knee dislocation during walking.

After first stage of operation, antibiotics are administered for 4∼8 wks until the CRP levels become normalized and clinical findings show no sign of infection.

The 2^nd stage of operation is planned when clinical and laboratory signs of infection subside. The decision whether to reimplant the prosthesis or not is based on the operation findings and polymorphonuclear cell count on frozen section. However operation findings are considered more important than the frozen section results for reimplantation.

If operative findings are clean, I do reimplanation even though the polymorphonuclear cell count is more than 5 on high power field(hpf) on frozen section.

I have adopted numbering system to take specimen. Number 1 is specimen from suprapatella pouch, No 2 is that from gap between the femur and tibia, No 3 is that from femoral intramedullary canal, No 4 is that from tibial intramedullary canal, and No 5 is that from most unhealthy site.

In a retrospective analysis of 16 cases which received reimplantation despite of the prescence of more than five polymorphonuclear cells on intra-operative frozen sections, none of the cases had recurrence of infection at a final follow up of 2 years. The femoral medullary canal was the most prevalent site for higher polymorphonuclear cell count.

In conclusion, indication is the first step for successful reimplantion. Two stage revision is recommended and meticulous debridement is utmost important in first stage operation. Block type antibiotic loaded cement is sufficient for a good result.

Clinical, laboratory and operative findings are more important than polymorphonuclear cell count on frozen section to decide reimplantation.

I propose numbering system of the specimen site for frozen section, just as in tumor surgery.

In a prospective multicentre study we investigated variations in pain management used by knee arthroplasty surgeons in order to compare the differences in pain levels among patients undergoing total knee replacements (TKR), and to compare the effectiveness of pain management protocols. The protocols, peri-operative levels of pain and patient satisfaction were investigated in 424 patients who underwent TKR in 14 hospitals. The protocols were highly variable and peri-operative pain levels varied substantially, particularly during the first two post-operative days. Differences in levels of pain were greatest during the night after TKR, when visual analogue scores ranged from 16.9 to 94.3 points.

Of the methods of managing pain, the combined use of peri-articular infiltration and nerve blocks provided better pain relief than other methods during the first two post-operative days. Patients managed with peri-articular injection plus nerve block, and epidural analgesia were more likely to have higher satisfaction at two weeks after TKR. This study highlights the need to establish a consistent pain management strategy after TKR.

We checked intraoperative patellar tracking with both ‘towel clip technique’ and the ‘no thumb technique’ on 354 patients (571 knees) who underwent primary total knee arthroplasty to decide whether to do or not to do lateral retinacular release.

All surgical procedures consisted of medial parapatellar arthrotomy and patellar resurfacing. Patellar tracking was assessed under pneumatic tourniquette with the no thumb technique first and reevaluated with the towel clip technique. The tracking was graded as total contact, good contact, lateral contact, and subluxation. The knees graded as total or good contact with the no thumb technique were classified into group A; those graded lateral contact or subluxation by the no thumb technique but total or good contact by the towel clip technique were classified into group B; and those graded lateral contact or subluxation by both techniques were classified into group C, in which lateral releases were performed. We classified 371, 148, and 52 knees into groups A, B, and C respectively. Patellar lateral tilting in the Merchant view was reviewed preoperatively and 2 weeks, 6 weeks, 6 months, and 1 year postoperatively.

There were no statistical differences on postoperative patellar tilting among the groups. Assessment of the patellar tracking using only the no thumb technique may overestimate the need for lateral retinacular release. The use of the no thumb technique as a screening test, and reevaluation with the towel clip technique, may reduce unnecessary lateral retinacular release.

There are three basic concepts that are important to the biomechanics of pedicle screw-based instrumentation. First, the outer diameter of the screw determines pullout strength, while the inner diameter determines fatigue strength. Secondly, when inserting a pedicle screw, the dorsal cortex of the spine should not be violated and the screws on each side should converge and be of good length. Thirdly, fixation can be augmented in cases of severe osteoporosis or revision.

A trajectory parallel or caudal to the superior endplate can minimise breakage of the screw from repeated axial loading. Straight insertion of the pedicle screw in the mid-sagittal plane provides the strongest stability.

Rotational stability can be improved by adding transverse connectors. The indications for their use include anterior column instability, and the correction of rotational deformity.

We analyzed the causes of 113 revision total knee arthroplasties in 84 patients between December 1996 and June 2008. Patient history, medical record and radiographs were reviewed to detect the main cause of failure of primary total knee arthroplasty. The causes of revision total knee arthroplasty were as follows: 44 infections (38.9 %), 34 loosenings (30.1%), 22 polyethylene wears or breakages (19.5%), 5 stiffness (4.4%), 4 polyethylene dislocations (3.5%), 2 patellar dislocations (1.8%), 1 patellar component failure and 1 instability (0.9%, each). The mean interval from the index operation to the revision surgery was 59 months (1 month-20 years).

Infection was the most common causes of revision TKA and followed by loosening, wear or breakage of polyethylene, stiff knee, dislocation of polyethylene and so on.

In 16 mature New Zealand white rabbits mesenchymal stem cells were aspirated from the bone marrow, cultured in monolayer and implanted on to a full-thickness osteochondral defect artificially made on the patellar groove of the same rabbit. A further 13 rabbits served as a control group. The rabbits were killed after 14 weeks. Healing of the defect was investigated histologically using haematoxylin and eosin and Safranin-O staining and with immunohistochemical staining for type-II collagen. We also used a reverse transcription-polymerase chain reaction (RT-PCR) to detect mRNA of type-I and type-II collagen.

The semiquantitative histological scores were significantly higher in the experimental group than in the control group (p < 0.05). In the experimental group immunohistochemical staining on newly formed cartilage was more intense for type-II collagen in the matrix and RT-PCR from regenerated cartilage detected mRNA for type-II collagen in mature chondrocytes. These findings suggest that repair of cartilage defects can be enhanced by the implantation of cultured mesenchymal stem cells.