High-flexion total knee replacement (TKR) designs
have been introduced to improve flexion after TKR. Although the
early results of such designs were promising, recent literature
has raised concerns about the incidence of early loosening of the
femoral component. We compared the minimum force required to cause
femoral component loosening for six high-flexion and six conventional
TKR designs in a laboratory experiment. Each TKR design was implanted in a femoral bone model and placed
in a loading frame in 135° of flexion. Loosening of the femoral
component was induced by moving the tibial component at a constant
rate of displacement while maintaining the same angle of flexion.
A stereophotogrammetric system registered the relative movement
between the femoral component and the underlying bone until loosening
occurred. Compared with high-flexion designs, conventional TKR designs
required a significantly higher force before loosening occurred
(p <
0.001). High-flexion designs with closed box geometry required
significantly higher loosening forces than high-flexion designs
with open box geometry (p = 0.0478). The presence of pegs further contributed
to the fixation strength of components. We conclude that high-flexion designs have a greater risk for
femoral component loosening than conventional TKR designs. We believe
this is attributable to the absence of femoral load sharing between
the prosthetic component and the condylar bone during flexion.
The Gamma nail is frequently used in unstable
peri-trochanteric hip fractures. We hypothesised that mechanical failure
of the Gamma nail was associated with inadequate proximal three-point
fixation. We identified a consecutive series of 299 Gamma nails
implanted in 299 patients over a five-year period, 223 of whom fulfilled
our inclusion criteria for investigation. The series included 61
men and 162 women with a mean age of 81 years (20 to 101). Their fractures
were classified according to the Modified Evans’ classification
and the quality of fracture reduction was graded. The technical
adequacy of three points of proximal fixation was recorded from
intra-operative fluoroscopic images, and technical inadequacy for
each point was defined. All patients were followed to final follow-up
and mechanical failures were identified. A multivariate statistical
analysis was performed, adjusting for confounders. A total of 16
failures (7.2%) were identified. The position of the lag screw relative
to the lateral cortex was the most important point of proximal fixation,
and when inadequate the failure rate was 25.8% (eight of 31: odds
ratio 7.5 (95% confidence interval 2.5 to 22.7), p <
0.001). Mechanical failure of the Gamma nail in peri-trochanteric femoral
fractures is rare (<
1%) when three-point proximal fixation is
achieved. However, when proximal fixation is inadequate, failure
rates increase. The strongest predictor of failure is positioning
the lateral end of the lag screw short of the lateral cortex. Adherence
to simple technical points minimises the risk of fixation failure
in this vulnerable patient group. Cite this article:
Total hip replacement for high dislocation of the hip joint remains technically difficult in terms of preparation of the true acetabulum and restoration of leg length. We describe our experience of cementless total hip replacement combined with a subtrochanteric femoral shortening osteotomy in 20 hips with Crowe grade IV dislocation with a mean follow-up of 8.1 years (4 to 11.5). There was one man and 17 women with a mean age of 55 years (44 to 69) at the time of the operation. After placment of the acetabular component at the site of the natural acetabulum, a cementless porous-coated cylindrical femoral component was implanted following a subtrochanteric femoral shortening osteotomy. The mean Japanese Orthopedic Association hip score improved from a mean of 38 (22 to 62) to a mean of 83 points (55 to 98) at the final follow-up. The mean lengthening of the leg was 14.8 mm (−9 to 34) in patients with iliofemoral osteoarthritis and 35.3 mm (15 to 51) in patients with no arthritic changes. No nerve palsy was observed. Total hip replacement combined with subtrochanteric shortening femoral osteotomy in this situation is beneficial in avoiding nerve injury and still permits valuable improvement in inequality of leg length.
Ten patients, who were unsuitable for limb lengthening over an intramedullary nail, underwent lengthening with a submuscular locking plate. Their mean age at operation was 18.5 years (11 to 40). After fixing a locking plate submuscularly on the proximal segment, an external fixator was applied to lengthen the bone after corticotomy. Lengthening was at 1 mm/day and on reaching the target length, three or four screws were placed in the plate in the distal segment and the external fixator was removed. All patients achieved the pre-operative target length at a mean of 4.0 cm (3.2 to 5.5). The mean duration of external fixation was 61.6 days (45 to 113) and the mean external fixation index was 15.1 days/cm (13.2 to 20.5), which was less than one-third of the mean healing index (48 days/cm (41.3 to 55). There were only minor complications. Lengthening with a submuscular locking plate can successfully permit early removal of the fixator with fewer complications and is a useful alternative in children or when nailing is difficult.
We report the results of 79 patients (81 hips)
who underwent impaction grafting at revision hip replacement using the
Exeter femoral stem. Their mean age was 64 years (31 to 83). According
to the Endoklinik classification, 20 hips had a type 2 bone defect,
40 had type 3, and 21 had type 4. The mean follow-up for unrevised
stems was 10.4 years (5 to 17). There were 12 re-operations due to intra- and post-operative
fractures, infection (one hip) and aseptic loosening (one hip).
All re-operations affected type 3 (6 hips) and 4 (6 hips) bone defects.
The survival rate for re-operation for any cause was 100% for type
2, 81.2% (95% confidence interval (CI) 67.1 to 95.3) for type 3,
and 70.8% (95% CI 51.1 to 90.5) for type 4 defects at 14 years.
The survival rate with further revision for aseptic loosening as
the end point was 98.6% (95% CI 95.8 to 100). The final clinical
score was higher for patients with type 2 bone defects than type
4 regarding pain, function and range of movement. Limp was most
frequent in the type 4 group (p <
0.001). The mean subsidence
of the stem was 2.3 mm ( The impacted bone grafting technique has good clinical results
in femoral revision. However, major bone defects affect clinical
outcome and also result in more operative complications.
Short intense electrical pulses transiently increase the permeability of the cell membrane, an effect known as electroporation. This can be combined with antiblastic drugs for ablation of tumours of the skin and subcutaneous tissue. The aim of this study was to test the efficacy of electroporation when applied to bone and to understand whether the presence of mineralised trabeculae would affect the capability of the electric field to porate the membrane of bone cells. Different levels of electrical field were applied to the femoral bone of rabbits. The field distribution and modelling were simulated by computer. Specimens of bone from treated and control rabbits were obtained for histology, histomorphometry and biomechanical testing. After seven days, the area of ablation had increased in line with the number of pulses and/or with the amplitude of the electrical field applied. The osteogenic activity in the ablated area had recovered by 30 days. Biomechanical testing showed structural integrity of the bone at both times. Electroporation using the appropriate combination of voltage and pulses induced ablation of bone cells without affecting the recovery of osteogenic activity. It can be an effective treatment in bone and when used in combination with drugs, an option for the treatment of metastases.
Our understanding of the origin of hip pain in
degenerative disorders of the hip, including primary osteoarthritis, avascular
necrosis and femoroacetabular impingement (FAI), is limited. We
undertook a histological investigation of the nociceptive innervation
of the acetabular labrum, ligamentum teres and capsule of the hip,
in order to prove pain- and proprioceptive-associated marker expression.
These structures were isolated from 57 patients who had undergone
elective hip surgery (44 labral samples, 33 ligamentum teres specimens,
34 capsular samples; in 19 patients all three structures were harvested).
A total of
15 000 histological sections were prepared that were investigated
immunohistochemically for the presence of protein S-100, 68 kDa
neurofilament, neuropeptide Y, nociceptin and substance P. The tissues
were evaluated in six representative areas. Within the labrum, pain-associated free nerve ending expression
was located predominantly at its base, decreasing in the periphery.
In contrast, the distribution within the ligamentum teres showed
a high local concentration in the centre. The hip capsule had an
almost homogeneous marker expression in all investigated areas. This study showed characteristic distribution profiles of nociceptive
and pain-related nerve fibres, which may help in understanding the
origin of hip pain. Cite this article:
To determine the morbidity and mortality outcomes of patients
presenting with a fractured neck of femur in an Australian context.
Peri-operative variables related to unfavourable outcomes were identified
to allow planning of intervention strategies for improving peri-operative
care. We performed a retrospective observational study of 185 consecutive
adult patients admitted to an Australian metropolitan teaching hospital
with fractured neck of femur between 2009 and 2010. The main outcome
measures were 30-day and one-year mortality rates, major complications
and factors influencing mortality. Objectives
Methods
Disarticulation of the hip in patients with high-grade tumours in the upper thigh results in significant morbidity. In patients with no disease of the proximal soft tissue a femoral stump may be preserved, leaving a fulcrum for movement and weight-bearing. We reviewed nine patients in whom the oncological decision would normally be to disarticulate, but who were treated by implantation of an endoprosthesis in order to create a functioning femoral stump. The surgery was undertaken for chondrosarcoma in four patients, pleomorphic sarcoma in three, osteosarcoma in one and fibrous dysplasia in one. At follow-up at a mean of 80 months (34 to 132), seven patients were alive and free from disease, one had died from lung metastases and another from a myocardial infarction. The mean functional outcome assessment was 50 (musculoskeletal tumor society), 50 and 60 (physical and mental Short-form 36 scores). Implantation of an endoprosthesis into the stump in carefully selected patients allows fitting of an above-knee prosthesis and improves wellbeing and the functional outcome.
We evaluated two reconstruction techniques for a simulated posterolateral corner injury on ten pairs of cadaver knees. Specimens were mounted at 30° and 90° of knee flexion to record external rotation and varus movement. Instability was created by transversely sectioning the lateral collateral ligament at its midpoint and the popliteus tendon was released at the lateral femoral condyle. The left knee was randomly assigned for reconstruction using either a combined or fibula-based treatment with the right knee receiving the other. After sectioning, laxity increased in all the specimens. Each technique restored external rotatory and varus stability at both flexion angles to levels similar to the intact condition. For the fibula-based reconstruction method, varus laxity at 30° of knee flexion did not differ from the intact state, but was significantly less than after the combined method. Both the fibula-based and combined posterolateral reconstruction techniques are equally effective in restoring stability following the simulated injury.
We identified eight patients of 2900 with a primary malignant bone tumour who had coexisting neurofibromatosis type 1. This was a much higher incidence than would be expected by chance. The patients had a mean age of 22.4 years (9 to 54): five were male. Two patients subsequently developed a second bone sarcoma, one of which was radiation induced. Four of the primary tumours were osteosarcomas, four were spindle-cell sarcomas and one a Ewing’s sarcoma. All the patients were treated with chemotherapy and surgery: six of the eight appear to be cured. This study suggests a possible relationship between neurofibromatosis type 1 and the development of a bone sarcoma, the increased risk being estimated at eight times that of the normal population. We recommend that further research into this possible link should be considered.
We undertook a prospective randomised controlled trial involving 400 patients with a displaced intracapsular fracture of the hip to determine whether there was any difference in outcome between treatment with a cemented Thompson hemiarthroplasty and an uncemented Austin-Moore prosthesis. The surviving patients were followed up for between two and five years by a nurse blinded to the type of prosthesis used. The mean age of the patients was 83 years (61 to 104) and 308 (77%) were women. The degree of residual pain was less in those treated with a cemented prosthesis (p <
0.0001) three months after surgery. Regaining mobility was better in those treated with a cemented implant (p = 0.005) at six months after operation. No statistically significant difference was found between the two groups with regard to mortality, implant-related complications, re-operations or post-operative medical complications. The use of a cemented Thompson hemiarthroplasty resulted in less pain and less deterioration in mobility than an uncemented Austin-Moore prosthesis with no increase in complications.
Orientation of the native acetabular plane as defined by the transverse acetabular ligament (TAL) and the posterior labrum was measured intra-operatively using computer-assisted navigation in 39 hips. In order to assess the influence of alignment on impingement, the range of movement was calculated for that defined by the TAL and the posterior labrum and compared with a standard acetabular component position (abduction 45°/anteversion 15°). With respect to the registration of the plane defined by the TAL and the posterior labrum, there was moderate interobserver agreement (r = 0.64, p <
0.001) and intra-observer reproducibility (r = 0.73, p <
0.001). The mean acetabular component orientation achieved was abduction of 41° (32° to 51°) and anteversion of 18° (−1° to 36°). With respect to the Lewinnek safe zone (abduction 40° ±10°, anteversion 15° ±10°), 35 of the 39 acetabular components were within this zone. However, there was no improvement in the range of movement (p = 0.94) and no significant difference in impingement (p = 0.085). Alignment of the acetabular component with the TAL and the posterior labrum might reduce the variability of acetabular component placement in total hip replacement. However, there is only a moderate interobserver agreement and intra-observer reliability in the alignment of the acetabular component using the TAL and the posterior labrum. No reduction in impingement was found when the acetabular component was aligned with the TAL and the posterior labrum, compared with a standard acetabular component position.
Femoral lengthening using the Intramedullary Skeletal Kinetic Distractor is a new technique. However, with intramedullary distraction the surgeon has less control over the lengthening process. Therefore, 33 femora lengthened with this device were assessed to evaluate the effect of operative variables under the surgeon’s control on the course of lengthening. The desired lengthening was achieved in 32 of 33 limbs. Problems encountered included difficulty in achieving length in eight femora (24%) and uncontrolled lengthening in seven (21%). Uncontrolled lengthening was more likely if the osteotomy was placed with less than 80 mm of the thick portion of the nail in the distal fragment (p = 0.052), and a failure to lengthen was more likely if there was over 125 mm in the distal fragment (p = 0.008). The latter problem was reduced with over-reaming by 2.5 mm to 3 mm. Previous intramedullary nailing also predisposed to uncontrolled lengthening (p = 0.042), and these patients required less reaming. Using the Intramedullary Skeletal Kinetic Distractor, good outcomes were obtained; problems were minimised by optimising the position of the osteotomy and the amount of over-reaming performed.
We present the results of the surgical correction of lower-limb deformities caused by metabolic bone disease. Our series consisted of 17 patients with a diagnosis of hypophosphataemic rickets and two with renal osteodystrophy; their mean age was 25.6 years (14 to 57). In all, 43 lower-limb segments (27 femora and 16 tibiae) were osteotomised and the deformity corrected using a monolateral external fixator. The segment was then stabilised with locked intramedullary nailing. In addition, six femora in three patients were subsequently lengthened by distraction osteogenesis. The mean follow-up was 60 months (18 to 120). The frontal alignment parameters (the mechanical axis deviation, the lateral distal femoral angle and the medial proximal tibial angle) and the sagittal alignment parameters (the posterior distal femoral angle and the posterior proximal tibial angle) improved post-operatively. The external fixator was removed either at the end of surgery or at the end of the lengthening period, allowing for early mobilisation and weight-bearing. We encountered five problems and four obstacles in the programme of treatment. The use of intramedullary nails prevented recurrence of deformity and refracture.
The painful subluxed or dislocated hip in adults
with cerebral palsy presents a challenging problem. Prosthetic dislocation
and heterotopic ossification are particular concerns. We present
the first reported series of 19 such patients (20 hips) treated
with hip resurfacing and proximal femoral osteotomy. The pre-operative
Gross Motor Function Classification System (GMFCS) was level V in
13 (68%) patients, level IV in three (16%), level III in one (5%) and
level II in two (11%). The mean age at operation was 37 years (13
to 57). The mean follow-up was 8.0 years (2.7 to 11.6), and 16 of the
18 (89%) contactable patients or their carers felt that the surgery
had been worthwhile. Pain was relieved in 16 of the 18 surviving
hips (89%) at the last follow-up, and the GMFCS level had improved
in seven (37%) patients. There were two (10%) early dislocations;
three hips (15%) required revision of femoral fixation, and two
hips (10%) required revision, for late traumatic fracture of the
femoral neck and extra-articular impingement, respectively. Hence
there were significant surgical complications in a total of seven
hips (35%). No hips required revision for instability, and there
were no cases of heterotopic ossification. We recommend hip resurfacing with proximal femoral osteotomy
for the treatment of the painful subluxed or dislocated hip in patients
with cerebral palsy.
Deep prosthetic joint infection remains an uncommon but serious complication of total hip replacement. We reviewed 24 patients with recalcitrant hip wounds following infected total hip replacement treated with either pedicled rectus femoris or vastus lateralis muscle flaps between 1998 and 2009. The mean age of the patients was 67.4 years (42 to 86) with ten men and 14 women. There had been a mean of four (1 to 8) previous attempts to close the wound. A total of 20 rectus femoris and five vastus lateralis flaps were used, with one of each type of flap failing and requiring further reconstruction. All patients had positive microbiology. At a mean follow-up of 47 months (9 to 128), 22 patients had a healed wound and two had a persistent sinus. The prosthesis had been retained in five patients. In the remainder it had been removed, and subsequently re-implanted in nine patients. Six patients continued to take antibiotics at final follow-up. This series demonstrates the effectiveness of pedicled muscle flaps in healing these infected wounds. The high number of previous debridements suggests that these flaps could have been used earlier.
There are several methods for evaluating stability
of the joint during total knee replacement (TKR). Activities of daily
living demand mechanical loading to the knee joint, not only in
full extension, but also in mid-flexion. The purpose of this study
was to compare the varus-valgus stability throughout flexion in
knees treated with either cruciate-retaining or posterior-stabilised
TKR, using an intra-operative navigation technique. A total of 34
knees underwent TKR with computer navigation, during which the investigator
applied a maximum varus-valgus stress to the knee while steadily
moving the leg from full extension to flexion both before and after
prosthetic implantation. The femorotibial angle was measured simultaneously
by the navigation system at every 10° throughout the range of movement.
It was found that posterior-stabilised knees had more varus-valgus
laxity than cruciate-retaining knees at all angles examined, and
the differences were statistically significant at 10° (p = 0.0093),
20° (p = 0.0098) and 30° of flexion (p = 0.0252). Cite this article:
We undertook a randomised controlled trial to
compare bipolar hemiarthroplasty (HA) with a novel total hip replacement
(THR) comprising a polycarbonate–urethane (PCU) acetabular component
coupled with a large-diameter metal femoral head for the treatment
of displaced fractures of the femoral neck in elderly patients. Functional
outcome, assessed with the Harris hip score (HHS) at three months
and then annually after surgery, was the primary endpoint. Rates
of revision and complication were secondary endpoints. Based on a power analysis, 96 consecutive patients aged >
70
years were randomised to receive either HA (49) or a PCU-THR (47).
The mean follow-up was 30.1 months (23 to 50) and 28.6 months (22
to 52) for the HA and the PCU group, respectively. The HHS showed no statistically significant difference between
the groups at every follow-up. Higher pain was recorded in the PCU
group at one and two years’ follow-up
(p = 0.006 and p = 0.019, respectively). In the HA group no revision
was performed. In the PCU-THR group six patients underwent revision
and one patient is currently awaiting
re-operation. The three-year survival rate of the PCU-THR group
was 0.841 (95% confidence interval 0.680 to 0.926). Based on our findings we do not recommend the use of the PCU
acetabular component as part of the treatment of patients with fractures
of the femoral neck. Cite this article: