Cite this article: Bone Joint Open 2020;1-11:706–708.

Aims

Unicompartmental knee arthroplasty (UKA) has become a popular method of treating knee localized osteoarthritis (OA). Additionally, the posterior cruciate ligament (PCL) is essential to maintaining the physiological kinematics and functions of the knee joint. Considering these factors, the purpose of this study was to investigate the biomechanical effects on PCL-deficient knees in medial UKA.

Aims

To compare time dependent functional improvement for patients with medial, respectively lateral knee osteoarthritis (OA) after treatment with opening wedge osteotomy relieving the pressure on the osteoarthritic part of the knee.

Aims

Commonly performed unicompartmental knee arthroplasty (UKA) is not designed for the lateral compartment. Additionally, the anatomical medial and lateral tibial plateaus have asymmetrical geometries, with a slightly dished medial plateau and a convex lateral plateau. Therefore, this study aims to investigate the native knee kinematics with respect to the tibial insert design corresponding to the lateral femoral component.

Since the Oxford knee was first used unicompartmentally in 1982, a small number of bearings have fractured. Of 14 retrieved bearings, we examined ten samples with known durations in situ (four Phase 1, four Phase 2 and two Phase 3). Evidence of impingement and associated abnormally high wear (> 0.05 mm per year) as well as oxidation was observed in all bearings. In four samples the fracture was associated with the posterior radio-opaque wire. Fracture surfaces indicated fatigue failure, and scanning electron microscopy suggested that the crack initiated in the thinnest region. The estimated incidence of fracture was 3.20% for Phase 1, 0.74% for Phase 2, 0.35% for Phase 3, and 0% for Phase 3 without the posterior marker wire. The important aetiological factors for bearing fracture are impingement leading to high wear, oxidation, and the posterior marker wire. With improved surgical technique, impingement and high wear should be prevented and modern polyethylene may reduce the oxidation risk. A posterior marker wire is no longer used in the polyethylene meniscus. Therefore, the rate of fracture, which is now very low, should be reduced to a negligible level

1. The orientation of collagen fibres of the menisci of the knee has been demonstrated by polarised light microscopy. 2. As might be supposed from its fibre structure, the ultimate tensile strength of the meniscal tissue is dependent upon the axis of loading. 3. The tensile strength of the meniscus is similar to that of articular cartilage

The relationship between meniscal tearing and degenerative joint disease was studied by macroscopic examination of 115 knees at necropsy. The incidence of meniscal pathology was 57 per cent. There was no overall difference in the severity and distribution of tibiofemoral degeneration, whether the meniscus was torn or normal. We found little evidence that degenerative meniscal tears cause osteoarthritis or vice versa

1. Attention is drawn to the importance of taking tangential radiographs of the patella in all cases of injury to the knee, especially when there is difficulty in distinguishing between recurrent dislocation of the patella and tear of a meniscus. 2. New bone formation along the medial side of the patella confirms a diagnosis of recurrent dislocation. 3. The importance of Coleman's original observations is stressed

1. A method of finger dissection is described which provides a new approach to the anatomical study of structures in close relation to joints. 2. The volar part of the capsule of the finger joints is described, the attachment to the bones being particularly emphasised together with its form which is like that of a meniscus. 3. A gap between bone and tendon sheath is described. 4. Theoretical and clinical aspects of the local anatomy are discussed

Changes in the knee joint after meniscectomy include ridge formation, narrowing of the joint space, and flattening of the femoral condyle. Investigations suggest that these changes are due to loss of the weight-bearing function of the meniscus. Meniscectomy is not wholly innocuous; it interferes, at least temporarily, with the mechanics of the joint. It seems likely that narrowing of the joint space will predispose to early degenerative changes, but a connection between these appearances and later osteoarthritis is not yet established and is too indefinite to justify clinical deductions

Ten patients are reported who had sustained a partial rupture of the anterior cruciate ligament in a twisting injury of the knee. Nine of the 10 patients presented with a small effusion and pseudo-locking of the knee which was thought to be due to muscular spasm to prevent further ligamentous injury. The patients were examined clinically, under anaesthesia and by arthroscopy and the signs were found to be remarkably similar to those in patients with a tear of the medial meniscus. The mechanism of injury leading to partial rupture of the anterior cruciate ligament is discussed

A series of 135 knee arthroscopies has been reviewed to determine the accuracy of detection of meniscal lesions. Arthroscopy and double-contrast arthrography achieved similar accuracy (84 per cent and 86 per cent) in the diagnostically more difficult knees of the series. The combined accuracy of both examinations was 98 per cent. Arthroscopic difficulty in seeing the posterior third of the medial meniscus, and consequently tears in this region, is emphasised and discussed. Arthroscopy and arthrography are complementary in the diagnosis of difficult meniscal problems

We report a case of an apparent avulsion fracture of the posteromedial margin of the medial plateau of the tibia. This was associated with a tear of the medial meniscus and rupture of the anterior cruciate ligament (ACL). This triad has been previously reported, and the plateau fracture was related to the insertion of the semimembranosus tendon. The detailed investigation of our case and some experiments on cadaver knees showed that the injury was not an avulsion fracture but was produced by varus and external rotation forces on a flexed knee. It was due to the anterior subluxation of the medial tibial plateau after rupture of the ACL

From a total of 1571 surgically excised menisci, 112 (7.1 per cent) were found by gross and microscopic examination to contain one or more cysts. All of these cysts were associated with tears, either primarily horizontal or with a horizontal component. Tracks were often demonstrable leading from the tear to the cysts, and in some cases of osteoarthritis, detritus of bone could be found in their periphery. It is concluded that the cysts are fuelled by synovial fluid. The relationship of cysts to "myxoid" change of the meniscus is discussed

The significance of the posterior cruciate ligament in the stability of the knee was investigated in dogs and it was compared with that of the anterior cruciate ligament by studying the changes produced in the knee after transection of either ligament. Osteophyte formation and changes in articular cartilage were less prominent after division of the posterior cruciate ligament. A complete longitudinal tear of the medial meniscus was found in eight out of the 10 dogs who had undergone section of the anterior cruciate but in none of the 10 with section of the posterior cruciate. It appears that, in dogs at least, the posterior cruciate ligament is less important than the anterior in the stability of the knee

1. Ninety-eight cases of fracture of the upper end of the tibia treated by operative reduction have been reviewed. 2. The true split fractures and the mildly comminuted compression fractures showed the best results. The "mosaic" cases showed the least satisfactory results. 3. Age has scarcely any effect on the end-results and is consequently no contra-indication to operation. 4. Nearly half the patients regained normal or almost normal mobility in the knee joint. 5. In no case did a meniscus left in place cause symptoms indicating internal derangement

1. It is suggested that slow recovery and post-operative effusion after meniscectomy may often be due to "scar friction" when the incision in the synovial membrane is in contact with the non-articular surface of the femoral condyle. 2. The advantages of a horizontal incision are discussed, particularly with regard to early recovery. 3. The results of one hundred and three cases of meniscectomy are analysed. An attempt to trace the cause of incompletely successful results in 25 per cent. of cases failed to show any relation to minor coincident lesions discovered at operation, or to the amount of meniscus removed

It is well recognised that meniscal tears situated within the inner, avascular region do not heal. We investigated the potential effect of insulin-like growth factor-I (IGF-I) in promoting regeneration of meniscal tissue in the inner, middle and outer zones of the meniscus. Sheep menisci were harvested and monolayer cell cultures prepared. Various concentrations of IGF-I were used in the presence or absence of 10% fetal calf serum (FCS). We measured the uptake of radioactive thymidine, sulphur, and proline to assess cell proliferation and formation of extracellular matrix (ECM). IGF-I, in the presence or absence of FCS, increased the formation of DNA and ECM in all meniscal zones. However, the response of the cells from the avascular zone was greater than that from the vascular zone. Our findings indicate that fibrochondrocytes cultured from avascular meniscal tissue have the ability to regenerate when exposed to anabolic cytokines such as IGF-I

A biomechanical study has been carried out on 20 cadaveric knees to investigate their load-absorbing mechanism. The impact load was applied using a weight falling onto the transected proximal femur and the force transmitted through the knee was measured at the transected distal tibia using a load transducer. The peak force transmitted increased as, sequentially, meniscus, articular cartilage and subchondral bone were damaged or removed. The most striking result was found in an implanted knee replacement where the transmitted force reached 180% of that in the intact knee. The results show that the joint has an impact-absorbing property in each segment and that in the osteoarthritic knee there is less absorption of shock than in the normal knee. The high impact force in an implanted knee suggests that microfractures of the cancellous bone might be expected and may produce loosening