Fractures of the distal humeral articular surface which do not involve the medial and lateral columns are often more extensive than is apparent from plain radiographs. This retrospective study describes the epidemiology of this injury using modern classification systems and compares pre-operative radiography with operative findings. The study group included 79 patients with a mean age of 47 years (13 to 91). The annual incidence was 1.5 per 100 000 population, and was highest in women over the age of 60. The majority of the fractures (59; 75%) were sustained in falls from standing height. Young males tended to sustain more high-energy injuries with more complex fracture patterns. In 24% of cases (19) there was a concomitant radial head fracture. Classification from plain radiographs often underestimates the true extent of the injury and computed tomography may be of benefit in pre-operative planning, especially in those over 60 years of age

We report a study of the shapes of the tibial and femoral articular surfaces in sagittal, frontal and coronal planes which was performed on cadaver knees using two techniques, MRI and computer interpolation of sections of the articular surfaces acquired by a three-dimensional digitiser. The findings using MRI, confirmed in a previous study by dissection, were the same as those using the digitiser. Thus both methods appear to be valid anatomical tools. The tibial and femoral articular surfaces can be divided into anterior segments, contacting from 0° to 20 ± 10° of flexion, and posterior segments, contacting from 20 ± 10° to 120° of flexion. The medial and lateral compartments are asymmetrical, particularly anteriorly. Posteromedially, the femur is spherical and is located in a conforming, but partly deficient, tibial socket. Posterolaterally, it is circular only in the sagittal section and the tibia is flat centrally, sloping downwards both anteriorly and posteriorly to receive the meniscal horns. Anteromedially, the femur is convex with a sagittal radius larger than that posteriorly, while the tibia is flat sloping upwards and forwards. Anterolaterally, both the femoral and tibial surfaces are largely deficient. These shapes suggest that medially the femur can rotate on the tibia through three axes intersecting in the middle of the femoral sphere, but that the sphere can only translate anteroposteriorly and even then to a limited extent. Laterally, the femur can freely translate anteroposteriorly, but can only rotate around a transverse axis for that part of the arc, i.e., near extension, during which it comes into contact with the tibia through its flattened distal/medial surface as against its spherical posterior surface

Allografts of intact cartilage, isolated chondrocytes and cultured chondrocytes taken from the epiphysial growth-plate and from the articular surface of immature rabbits were inserted into full thickness defects in the tibial articular surface of 160 mature rabbits. In the contralateral knees, which were used as controls, similar defects were made but no grafts were inserted. Grafts were followed up for periods of up to one year after transplantation. Both intact articular and intact growth-plate grafts produced significantly better repair than that seen in control ungrafted defects in normal joints (P less than 0.01 and P less than 0.05 respectively) and in arthritic joints (P less than 0.01). Cultured chondrocytes cut to a precise fit also produced significantly better repair than ungrafted defects in arthritic joints (P less than 0.05)

Bone loss involving articular surface is a challenging problem faced by the orthopaedic surgeon. In the hand and wrist, there are articular defects that are amenable to autograft reconstruction when primary fixation is not possible. In this article, the surgical techniques and clinical outcomes of articular reconstructions in the hand and wrist using non-vascularised osteochondral autografts are reviewed

We have studied damage to the tibial articular surface after replacement of the femoral surface in dogs. We inserted pairs of implants made of alumina, titanium and polyvinyl alcohol (PVA) hydrogel on titanium fibre mesh into the femoral condyles. The two hard materials caused marked pathological changes in the articular cartilage and menisci, but the hydrogel composite replacement caused minimal damage. The composite osteochondral device became rapidly attached to host bone by ingrowth into the supporting mesh. We discuss the clinical implications of the possible use of this material in articular resurfacing and joint replacement

In an attempt to repair articular cartilage, allograft articular chondrocytes embedded in collagen gel, were transplanted into full-thickness defects in rabbit articular cartilage. Twenty-four weeks after the transplantation, the defects were filled with hyaline cartilage, specifically synthesising Type II collagen. These chondrocytes were autoradiographically proven to have originated from the transplanted grafts. Assessed histologically the success rate was about 80%, a marked improvement over the results reported in previous studies on chondrocyte transplantation without collagen gel. By contrast, the defects without chondrocyte transplantation healed with fibrocartilage. Immunological enhancement induced by transplanted allogenic chondrocytes or collagen was not significant at eight weeks after treatment, so far as shown by both direct and indirect blastformation reactions. Thus, allogenic transplantation of isolated chondrocytes embedded in collagen gel appears to be one of the most promising methods for the restoration of articular cartilage.

We describe a lumbar facet syndrome in which disabling symptoms are associated with normal or near-normal plain radiographs. Local spinal fusion relieved symptoms in 12 patients; the excised facet joint surfaces showed some of the histological changes seen in chondromalacia patellae and in osteoarthritis of other large joints. The most frequent change was focal full-thickness cartilage necrosis or loss of cartilage with exposure of subchondral bone, but osteophyte formation was remarkably absent in all specimens. We suggest that there are both clinical and histological similarities between the facet arthrosis syndrome and chondromalacia patellae. Facet arthrosis may be a relatively important cause of intractable back pain in young and middle-aged adults.

We undertook this study to determine the minimum amount of coronoid necessary to stabilise an otherwise intact elbow joint. Regan–Morrey types II and III, plus medial and lateral oblique coronoid fractures, collectively termed type IV fractures, were simulated in nine fresh cadavers. An electromagnetic tracking system defined the three-dimensional stability of the ulna relative to the humerus. The coronoid surface area accounts for 59% of the anterior articulation. Alteration in valgus, internal and external rotation occurred only with a type III coronoid fracture, accounting for 68% of the coronoid and 40% of the entire articular surface. A type II fracture removed 42% of the coronoid articulation and 25% of the entire articular surface but was associated with valgus and external rotational changes only when the radial head was removed, thereby removing 67% of the articular surface. We conclude that all type III fractures, as defined here, are unstable, even with intact ligaments and a radial head. However, a type II deficiency is stable unless the radial head is removed. Our study suggests that isolated medial-oblique or lateral-oblique fractures, and even a type II fracture with intact ligaments and a functional radial head, can be clinically stable, which is consistent with clinical observation.

Aims. The aims of this study were to evaluate wear on the surface of cobalt-chromium (CoCr) femoral components used in total knee arthroplasty (TKA) and compare the wear of these components with that of ceramic femoral components. Methods. Optical profilometry was used to evaluate surface roughness and to examine the features created by the wear process in a knee wear simulator. We developed a method of measuring surface changes on five CoCr femoral components and quantifying the loss of material from the articular surface during the wear process. We also examined the articular surface of three ceramic femoral components from a previous test for evidence of surface damage, and compared it with that of CoCr components. Results. We found that the surface roughness of CoCr components rapidly increased during the first 1,000 wear cycles, then reached a steady state, but material loss from the surface continued at a rate of 1,778,000 μm. 3. per million cycles as carbides were removed from its matrix. These carbides formed third-body wear particles, leading to the formation of new scratches even as older scratches were worn away. In contrast, no scratching, loss of material, or other surface damage, when evaluated with one nanometer resolution, was found on the surface of the ceramic components after a 15 M wear cycle test. Conclusion. This study showed wear and loss of CoCr material from scratching and microabrasive wear in TKA. The material loss from the surface continued in a linear relationship with increasing cycles. We also found the absence of scratching and roughening of ceramic femoral components in simulated wear, suggesting an advantage in wear rate and avoiding metal sensitivity. This may have implications in the management of persistent pain after TKA. Cite this article: Bone Joint J 2021;103-B(6 Supple A):94–101

The Oxford Unicompartmental Knee replacement (UKR) was introduced as a design to reduce polyethylene wear. There has been one previous retrieval study involving this implant, which reported very low rates of wear in some specimens but abnormal patterns of wear in others. There has been no further investigation of these abnormal patterns. The bearings were retrieved from 47 patients who had received a medial Oxford UKR for anteromedial osteoarthritis of the knee. None had been studied previously. The mean time to revision was 8.4 years (. sd. 4.1), with 20 having been implanted for over ten years. The macroscopic pattern of polyethylene wear and the linear penetration were recorded for each bearing. The mean rate of linear penetration was 0.07 mm/year. The patterns of wear fell into three categories, each with a different rate of linear penetration; 1) no abnormal macroscopic wear and a normal articular surface, n = 16 (linear penetration rate = 0.01 mm/year); 2) abnormal macroscopic wear and normal articular surfaces with extra-articular impingement, n = 16 (linear penetration rate = 0.05 mm/year); 3) abnormal macroscopic wear and abnormal articular surfaces with intra-articular impingement +/− signs of non-congruous articulation, n = 15 (linear penetration rate = 0.12 mm/year). The differences in linear penetration rate were statistically significant (p < 0.001). These results show that very low rates of polyethylene wear are possible if the device functions normally. However, if the bearing displays suboptimal function (extra-articular, intra-articular impingement or incongruous articulation) the rates of wear increase significantly

Our aim was to determine the effect of the initial pattern of fracture and the displacement of fragments on the outcome of proximal humeral fractures treated conservatively. We followed 93 consecutive patients prospectively for one year. Final movement and strength were compared with those of the contralateral side. The final American Shoulder and Elbow Society score and the Disabilities of Arm, Shoulder and Hand and Short-Form 36 questionnaires were compared with those provided by the patient on the day of the injury. Radiographs and CT scans with three-dimensional reconstruction were obtained in all patients. The pattern of the fracture and the displacement of individual fragments were analysed and correlated with the final outcome. There were two cases of nonunion and six of avascular necrosis. The majority of the fractures (84 patients; 90%) followed one of the following four patterns: posteromedial (varus) impaction in 50 patients (54%), lateral (valgus) impaction in 13 (14%), isolated greater tuberosity in 15 (16%), and anteromedial impaction fracture in six (6%). Head orientation, impaction of the surgical neck and displacement of the tuberosity correlated strongly with the outcome. In fractures with posteromedial impaction, a poor outcome was noted as the articular surface displaced inferiorly increasing its distance from the acromion. A poorer outcome was noted as a fractured greater tuberosity displaced medially overlapping with the posterior articular surface. Lateral impaction fractures had a worse outcome than other patterns of fracture

The treatment of a chronic posterior dislocation of the shoulder is often determined by the size of the associated impression fracture of the humeral head. Our hypothesis was that patients with a chronic unreduced posterior dislocation of the shoulder and a defect in the humeral head involving between 25% to 50% of the articular surface, would do better if reconstructed with an allograft from the femoral head rather than treated by a non-anatomical reconstruction. We reviewed ten men and three women with a mean age of 42 years (36 to 51) at a mean follow-up of 54 months (41 to 64) who had this procedure. At follow-up, nine had no pain or restriction of activities of daily living. Their mean Constant-Murley shoulder score was 86.8 (43 to 98). No patient had symptoms of instability of the shoulder. Reconstruction of the defect in the humeral head with an allograft provides good pain relief, stability and function for patients with a locked, chronic posterior dislocation where the defect involves between 25% and 50% of the circumference of the articular surface

We developed a new porous scaffold made from a synthetic polymer, poly(DL-lactide-co-glycolide) (PLG), and evaluated its use in the repair of cartilage. Osteochondral defects made on the femoral trochlear of rabbits were treated by transplantation of the PLG scaffold, examined histologically and compared with an untreated control group. Fibrous tissue was initially organised in an arcade array with poor cellularity at the articular surface of the scaffold. The tissue regenerated to cartilage at the articular surface. In the subchondral area, new bone formed and the scaffold was absorbed. The histological scores were significantly higher in the defects treated by the scaffold than in the control group (p < 0.05). Our findings suggest that in an animal model the new porous PLG scaffold is effective for repairing full-thickness osteochondral defects without cultured cells and growth factors

Surgical reconstruction of articular surfaces by transplantation of osteochondral autografts has shown considerable promise in the treatment of focal articular lesions. During mosaicplasty, each cylindrical osteochondral graft is centred over the recipient hole and delivered by impacting the articular surface. Impact loading of articular cartilage has been associated with structural damage, loss of the viability of chondrocytes and subsequent degeneration of the articular cartilage. We have examined the relationship between single-impact loading and chondrocyte death for the specific confined-compression boundary conditions of mosaicplasty and the effect of repetitive impact loading which occurs during implantation of the graft on the resulting viability of the chondrocytes. Fresh bovine and porcine femoral condyles were used in this experiment. The percentage of chondrocyte death was found to vary logarithmically with single-impact energy and was predicted more strongly by the mean force of the impact rather than by the number of impacts required during placement of the graft. The significance of these results in regard to the surgical technique and design features of instruments for osteochondral transplantation is discussed

Aims. A retrospective longitudinal study was conducted to compare directly volumetric wear of retrieved polyethylene inserts to predicted volumetric wear modelled from individual gait mechanics of total knee arthroplasty (TKA) patients. Methods. In total, 11 retrieved polyethylene tibial inserts were matched with gait analysis testing performed on those patients. Volumetric wear on the articular surfaces was measured using a laser coordinate measure machine and autonomous reconstruction. Knee kinematics and kinetics from individual gait trials drove computational models to calculate medial and lateral tibiofemoral contact paths and forces. Sliding distance along the contact path, normal forces and implantation time were used as inputs to Archard’s equation of wear to predict volumetric wear from gait mechanics. Measured and modelled wear were compared for each component. Results. Volumetric wear rates on eight non-delaminated components measured 15.9 mm. 3. /year (standard error (SE) ± 7.7) on the total part, 11.4 mm. 3. /year (SE ± 6.4) on the medial side and 4.4 (SE ± 2.6) mm. 3. /year on the lateral side. Volumetric wear rates modelled from patient gait mechanics predicted 16.4 mm. 3. /year (SE 2.4) on the total part, 11.7 mm. 3. /year (SE 2.1) on the medial side and 4.7 mm. 3. /year (SE 0.4) on the lateral side. Measured and modelled wear volumes correlated significantly on the total part (p = 0.017) and the medial side (p = 0.012) but not on the lateral side (p = 0.154). Conclusion. In the absence of delamination, patient-specific knee mechanics during gait directly affect wear of the tibial component in TKA. Cite this article: Bone Joint J 2020;102-B(6 Supple A):129–137

The experiments were performed to answer three main questions. These and our answers may be summarised as follows. What is the precise mechanism of healing of a raw bony surface in a joint? What cells are involved? Where do they originate?—In all the implant experiments and in the control series the fundamental mechanism of healing was similar. 1. A massive proliferation of fibroblasts occurred from the cut periosteum, from the cut joint capsule, and to a lesser extent from the medullary canal. 2. Fibroblasts grew centripetally in the first few weeks after operation, attempting to form a "fibroblast cap" to the cut bone end. 3. Fibroblasts of this cap near the cut bone spicules metamorphosed to become prechondroblasts, chondroblasts laying down cartilage matrix, and hypertrophied (alkaline phosphatase-secreting) chondrocytes lying in a calcified matrix. 4. This calcified cartilage matrix was invaded by dilated capillaries probably bearing osteoblasts which laid down perivascular (endochondral) bone. 5. Some of the cells of projecting bone spicules died and their matrix was eroded in the presence of many osteoclasts. 6. In the control experiments of simple excision of the radial head new bone was produced at the periphery only by processes (3) and (4). This sealed off the underlying peripheral cortical bone from the superficially placed peripheral articular surface of fibrocartilage. At about a year from operation the central portion of the articular surface was still formed of bare bone, or of bone spicules covered by a thin layer of irregularly arranged collagen fibres. The opposite capitular articular cartilage was badly eroded. Does the introduction of a dead cartilage implant over the raw bone end affect in any way the final constitution of the new articular surface?—In the implant experiments the new bone produced by processes (3) and (4) formed, after about a year, a complete cortical plate which entirely sealed off the cut end of the radius and left a superficially placed articular covering of smooth fibrocartilage, closely resembling a normal joint surface. The opposite capitular articular surface was normal. What is the final fate of such an implant?—Whale cartilage implants underwent replacement by fibroblasts and collagen fibres, and took about nine months to disappear. The cartilage of fixed autotransplants and homotransplants underwent similar gradual replacement, and took about the same time in each case. The dead bone, implanted in association with the cartilage in both cases, acted as a nidus for hyaline cartilage production by chondrocytes derived from fibroblasts. This cartilage underwent endochondral ossification. This observation suggests that induction by non-cellular osseous material is a factor in chondrification and ossification. All the implants functioned as temporary articular menisci or in some cases as temporary radial articular surfaces. They were always replaced by a permanent fibrocartilaginous meniscus, or a fibrocartilaginous articular surface. An implant did, in fact, always act as a temporary protecting cap and mould for the subjacent growth offibroblasts which was necessary for the production of a satisfactory new joint surface

Aims. The aim of this study was to evaluate the surface damage, the density of crosslinking, and oxidation in retrieved antioxidant-stabilized highly crosslinked polyethylene (A-XLPE) tibial inserts from total knee arthroplasty (TKA), and to compare the results with a matched cohort of standard remelted highly crosslinked polyethylene (XLPE) inserts. Materials and Methods. A total of 19 A-XLPE tibial inserts were retrieved during revision TKA and matched to 18 retrieved XLPE inserts according to the demographics of the patients, with a mean length of implantation of 15 months (1 to 42). The percentage areas of PE damage on the articular surfaces and the modes of damage were measured. The density of crosslinking of the PE and oxidation were measured at loaded and unloaded regions on these surfaces. Results. A-XLPE inserts had higher rates of burnishing and lower rates of pitting and scratching compared with XLPE. There were no differences in the density of crosslinking at loaded and unloaded regions. A-XLPE showed higher oxidation indices in the unloaded surface region compared with XLPE. There were no differences in the levels of oxidation in the loaded regions. Conclusion. Retrieval analysis of A-XLPE did not reflect a clinically relevant difference in surface damage, density of crosslinking, or oxidation compared with XLPE tibial inserts at short-term evaluation. Cite this article: Bone Joint J 2018;100-B:1330–5

We investigated the three-dimensional morphological differences of the articular surface of the femoral trochlea in patients with recurrent dislocation of the patella and a normal control group using three-dimensional computer models. There were 12 patients (12 knees) and ten control subjects (ten knees). Three-dimensional computer models of the femur, including the articular cartilage, were created. Evaluation was performed on the shape of the articular surface, focused on its convexity, and the proximal and mediolateral distribution of the articular cartilage of the femoral trochlea. The extent of any convexity, and the proximal distribution of the articular cartilage, expressed as the height, were shown by the angles about the transepicondylar axis. The mediolateral distribution of the articular cartilage was assessed by the location of the medial and lateral borders of the articular cartilage. The mean extent of convexity was 24.9° . sd. 6.7° for patients and 11.9° . sd. 3.6° for the control group (p < 0.001). The mean height of the articular cartilage was 91.3° . sd. 8.3° for the patients and 83.3° . sd. 7.7° for the control group (p = 0.03), suggesting a wider convex trochlea in the patients with recurrent dislocation of the patella caused by the proximally-extended convex area. The lateral border of the articular cartilage of the trochlea in the patients was more laterally located than in the control group. Our findings therefore quantitatively demonstrated differences in the shape and distribution of the articular cartilage on the femoral trochlea between patients with dislocation of the patella and normal subjects

We report the experimental use of three different biological implants to restore articular surface defects: glutaraldehyde-fixed bovine meniscal xenograft, glutaraldehyde-fixed bovine costal cartilage xenograft, and viable osteochondral allografts. The grafts were implanted in the knees of 19 goats who were allowed free-field activity and were studied for up to one year. The natural articular surfaces of meniscal fibrocartilage provided excellent articular surfaces at all times. Equally good articular surfaces were restored by host tissue growth covering costal cartilage grafts at six months, but by 12 months this surface had degenerated. The majority of the allografts survived and integrated with the host at six months, but many showed signs of failure at 12 months. Only three out of seven ungrafted defects healed completely at six months and the healed surfaces were degenerating at 12 months

Aims. This study aims to determine the proportion of patients with end-stage knee osteoarthritis (OA) possibly suitable for partial (PKA) or combined partial knee arthroplasty (CPKA) according to patterns of full-thickness cartilage loss and anterior cruciate ligament (ACL) status. Methods. A cross-sectional analysis of 300 consecutive patients (mean age 69 years (SD 9.5, 44 to 91), mean body mass index (BMI) 30.6 (SD 5.5, 20 to 53), 178 female (59.3%)) undergoing total knee arthroplasty (TKA) for Kellgren-Lawrence grade ≥ 3 knee OA was conducted. The point of maximal tibial bone loss on preoperative lateral radiographs was determined as a percentage of the tibial diameter. At surgery, Lachman’s test and ACL status were recorded. The presence of full-thickness cartilage loss within 16 articular surface regions (two patella, eight femoral, six tibial) was recorded. Results. According to articular cartilage loss and ACL status, 195/293 (67%) were suitable for PKA or CPKA: medial unicompartmental knee arthroplasty (UKA) 97/293 (33%); lateral UKA 25 (9%); medial bicompartmental arthroplasty 31 (11%); lateral bicompartmental arthroplasty 12 (4%); bicondylar-UKA 23 (8%); and patellofemoral arthroplasty (PFA) seven (2%). The ACL was intact in 166 (55%), frayed in 82 (27%), disrupted in 12 (4%), and absent in 33 (11%). Lachman testing was specific (97%) but poorly sensitive (38%) for disrupted/absent ACLs. The point of maximal tibial bone loss showed good interclass correlation (ICC 0.797, 0.73 to 0.85 95% confidence interval (CI); p < 0.001) and was more posterior when the ACL was absent. Maximum tibial bone loss occurring at > 55% of the anterior to posterior distance predicted ACL absence with 93% sensitivity and 91% specificity (area under the curve 0.97 (0.94 to 0.99 95% CI; p < 0.001). Conclusion. ACL status can be reliably determined from a lateral radiograph using the location of maximal tibial bone loss. According to regions of cartilage loss and ACL status, two-thirds of patients with end-stage knee OA could potentially be treated with PKA or CPKA. Cite this article: Bone Joint J 2020;102-B(6):716–726