Aims. This study aimed to use intraoperative free electromyography to examine how the placement of a retractor at different positions along the anterior acetabular wall may affect the femoral nerve during total hip arthroplasty (THA) when undertaken using the direct anterior approach (THA-DAA). Methods. Intraoperative free electromyography was performed during primary THA-DAA in 82 patients (94 hips). The highest position of the anterior acetabular wall was defined as the “12 o’clock” position (middle position) when the patient was in supine position. After exposure of the acetabulum, a retractor was sequentially placed at the ten, 11, 12, one, and two o’clock positions (right hip; from superior to inferior positions). Action potentials in the femoral nerve were monitored with each placement, and the incidence of positive reactions (defined as explosive, frequent, or continuous action potentials, indicating that the nerve was being compressed) were recorded as the primary outcome. Secondary outcomes included the incidence of positive reactions caused by removing the femoral head, and by placing a retractor during femoral exposure; and the incidence of femoral nerve palsy, as detected using manual testing of the strength of the quadriceps muscle. Results. Positive reactions were significantly less frequent when the retractor was placed at the ten (15/94; 16.0%), 11 (12/94; 12.8%), or 12 o’clock positions (19/94; 20.2%), than at the one (37/94; 39.4%) or two o’clock positions (39/94; 41.5%) (p < 0.050). Positive reactions also occurred when the femoral head was removed (28/94; 29.8%), and when a retractor was placed around the proximal femur (34/94; 36.2%) or medial femur (27/94; 28.7%) during femoral exposure. After surgery, no patient had reduced strength in the quadriceps muscle. Conclusion. Placing the anterior acetabular retractor at the one or two o’clock positions (right hip; inferior positions) during THA-DAA can increase the rate of electromyographic signal changes in the femoral nerve. Thus, placing a retractor in these positions may increased the risk of the development of a femoral nerve palsy. Cite this article: Bone Joint J 2022;104-B(2):193–199

Aims

The aim of this study was to compare the pattern of initial fixation and changes in periprosthetic bone mineral density (BMD) between patients who underwent total hip arthroplasty (THA) using a traditional fully hydroxyapatite (HA)-coated stem (T-HA group) and those with a newly introduced fully HA-coated stem (N-HA group).

Aims

The aims of this study were to investigate the ability to kneel after total knee arthroplasty (TKA) without patellar resurfacing, and its effect on patient-reported outcome measures (PROMs). Secondary aims included identifying which kneeling positions were most important to patients, and the influence of radiological parameters on the ability to kneel before and after TKA.

Aims

Dual plating of distal femoral fractures with medial and lateral implants has been performed to improve construct mechanics and alignment, in cases where isolated lateral plating would be insufficient. This may potentially compromise vascularity, paradoxically impairing healing. This study investigates effects of single versus dual plating on distal femoral vascularity.

Aims

Although knee osteoarthritis (OA) is diagnosed and monitored radiologically, actual full-thickness cartilage loss (FTCL) has rarely been correlated with radiological classification. This study aims to analyze which classification system correlates best with FTCL and to assess their reliability.

Aims

There is insufficient evidence to recommend the use of alternative polyethylene bearings in modular, fixed-bearing total knee arthroplasty (TKA). The purpose of this study was to compare standard polyethylene (SP) and highly crosslinked polyethylene (XLP) tibial liners in posterior-stabilized TKA, with osteolysis as the primary outcome and clinical results and the rate of re-operation as the secondary outcomes.

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

Although it has been suggested that the outcome after revision of a unicondylar knee replacement (UKR) to total knee replacement (TKR) is better when the mechanism of failure is understood, a comparative study on this subject has not been undertaken.

A total of 30 patients (30 knees) who underwent revision of their unsatisfactory UKR to TKR were included in the study: 15 patients with unexplained pain comprised group A and 15 patients with a defined cause for pain formed group B. The Oxford knee score (OKS), visual analogue scale for pain (VAS) and patient satisfaction were assessed before revision and at one year after revision, and compared between the groups.

The mean OKS improved from 19 (10 to 30) to 25 (11 to 41) in group A and from 23 (11 to 45) to 38 (20 to 48) in group B. The mean VAS improved from 7.7 (5 to 10) to 5.4 (1 to 8) in group A and from 7.4 (2 to 9) to 1.7 (0 to 8) in group B. There was a statistically significant difference between the mean improvements in each group for both OKS (p = 0.022) and VAS (p = 0.002). Subgroup analysis in group A, performed in order to define a patient factor that predicts outcome of revision surgery in patients with unexplained pain, showed no pre-operative differences between both subgroups.

These results may be used to inform patients about what to expect from revision surgery, highlighting that revision of UKR to TKR for unexplained pain generally results in a less favourable outcome than revision for a known cause of pain.

Cite this article: Bone Joint J 2013;95-B:1204–8.

We prospectively followed 191 consecutive collarless polished tapered (CPT) femoral stems, implanted in 175 patients who had a mean age at operation of 64.5 years (21 to 85). At a mean follow-up of 15.9 years (14 to 17.5), 86 patients (95 hips) were still alive. The fate of all original stems is known. The 16-year survivorship with re-operation for any reason was 80.7% (95% confidence interval 72 to 89.4). There was no loss to follow-up, with clinical data available on all 95 hips and radiological assessment performed on 90 hips (95%). At latest follow-up, the mean Harris hip score was 78 (28 to 100) and the mean Oxford hip score was 36 (15 to 48). Stems subsided within the cement mantle, with a mean subsidence of 2.1 mm (0.4 to 19.2). Among the original cohort, only one stem (0.5%) has been revised due to aseptic loosening. In total seven stems were revised for any cause, of which four revisions were required for infection following revision of the acetabular component. A total of 21 patients (11%) required some sort of revision procedure; all except three of these resulted from failure of the acetabular component. Cemented acetabular components had a significantly lower revision burden (three hips, 2.7%) than Harris Galante uncemented components (17 hips, 21.8%) (p < 0.001).

The CPT stem continues to provide excellent radiological and clinical outcomes at 15 years following implantation. Its results are consistent with other polished tapered stem designs.

We describe the technique and results of medial submuscular plating of the femur in paediatric patients and discuss its indications and limitations. Specifically, the technique is used as part of a plate-after-lengthening strategy, where the period of external fixation is reduced and the plate introduced by avoiding direct contact with the lateral entry wounds of the external fixator pins. The technique emphasises that vastus medialis is interposed between the plate and the vascular structures.

A total of 16 patients (11 male and five female, mean age 9.6 years (5 to 17)), had medial submuscular plating of the femur. All underwent distraction osteogenesis of the femur with a mean lengthening of 4.99 cm (3.2 to 12) prior to plating. All patients achieved consolidation of the regenerate without deformity. The mean follow-up was 10.5 months (7 to 15) after plating for those with plates still in situ, and 16.3 months (1 to 39) for those who subsequently had their plates removed. None developed a deep infection. In two patients a proximal screw fractured without loss of alignment; one patient sustained a traumatic fracture six months after removal of the plate.

Placing the plate on the medial side is advantageous when the external fixator is present on the lateral side, and is biomechanically optimal in the presence of a femoral defect. We conclude that medial femoral submuscular plating is a useful technique for specific indications and can be performed safely with a prior understanding of the regional anatomy.

Cite this article: Bone Joint J 2014;96-B:137–42.

The clinical diagnosis of a partial tear of the anterior cruciate ligament (ACL) is still subject to debate. Little is known about the contribution of each ACL bundle during the Lachman test. We investigated this using six fresh-frozen cadaveric lower limbs. Screws were placed in the femora and tibiae as fixed landmarks for digitisation of the bone positions. The femur was secured horizontally in a clamp. A metal hook was screwed to the tibial tubercle and used to apply a load of 150 N directed anteroposteriorly to the tibia to simulate the Lachman test. The knees then received constant axial compression and 3D knee kinematic data were collected by digitising the screw head positions in 30° flexion under each test condition. Measurements of tibial translation and rotation were made, first with the ACL intact, then after sequential cutting of the ACL bundles, and finally after complete division of the ACL. Two-way analysis of variance analysis was performed.

During the Lachman test, in all knees and in all test conditions, lateral tibial translation exceeded that on the medial side. With an intact ACL, both anterior and lateral tibial landmarks translated significantly more than those on the medial side (p < 0.001). With sequential division of the ACL bundles, selective cutting of the posterolateral bundle (PLB) did not increase translation of any landmark compared with when the ACL remained intact. Cutting the anteromedial bundle (AMB) resulted in an increased anterior translation of all landmarks. Compared to the intact ACL, when the ACL was fully transected a significant increase in anterior translation of all landmarks occurred (p < 0.001). However, anterior tibial translation was almost identical after AMB or complete ACL division.

We found that the AMB confers its most significant contribution to tibial translation during the Lachman test, whereas the PLB has a negligible effect on anterior translation. Section of the PLB had a greater effect on increasing the internal rotation of the tibia than the AMB. However, its contribution of a mean of 2.8° amplitude remains low. The clinical relevance of our investigation suggests that, based on anterior tibial translation only, one cannot distinguish between a full ACL and an isolated AMB tear. Isolated PLB tears cannot be detected solely by the Lachman test, as this bundle probably contributes more resistance to the pivot shift.

We matched 78 patients with a loose cemented Charnley Elite Plus total hip replacement (THR) by age, gender, race, prosthesis and time from surgery with 49 patients with a well-fixed stable hip replacement, to determine if poor bone quality predisposes to loosening. Clinical, radiological, biomechanical and bone mineral density indicators of bone quality were assessed.

Patients with loose replacements had more pain, were more likely to have presented with atrophic arthritis and to have a history of fragility fracture, narrower femoral cortices and lower peri-prosthetic or lumbar spine bone mineral density (all t-test, p < 0.01). They also tended to be smokers (chi-squared test, p = 0.08). Vitamin-D deficiency was common, but not significantly different between the two groups (t-test, p = 0.31)

In this series of cemented hip replacements performed between 1994 and 1998, aseptic loosening was associated with poor bone quality. Patients with a THR should be screened for osteoporosis and have regular radiological surveillance.