Stems improve the mechanical stability of tibial
components in total knee replacement (TKR), but come at a cost of stress
shielding along their length. Their advantages include resistance
to shear, reduced tibial lift-off and increased stability by reducing
micromotion. Longer stems may have disadvantages including stress
shielding along the length of the stem with associated reduction
in bone density and a theoretical risk of subsidence and loosening, peri-prosthetic
fracture and end-of-stem pain. These features make long stems unattractive
in the primary TKR setting, but often desirable in revision surgery
with bone loss and instability. In the revision scenario, stems
are beneficial in order to convey structural stability to the construct
and protect the reconstruction of bony defects. Cemented and uncemented
long stemmed implants have different roles depending on the nature
of the bone loss involved. This review discusses the biomechanics of the design of tibial
components and stems to inform the selection of the component and
the technique of implantation.
We have managed 27 patients (16 women and 11 men) with a mean age of 68.4 years (50 to 84), with failed total hip replacement and severe proximal femoral bone loss by revision using a distal fix/proximal wrap prosthesis. The mean follow-up was for 55.3 months (25 to 126). The mean number of previous operations was 2.2 (1 to 4). The mean Oxford hip score decreased from 46.2 (38 to 60) to 28.5 (17 to 42) (paired t-test, p <
0.001) and the mean Harris Hip score increased from 30.4 (3 to 57.7) to 71.7 (44 to 99.7) (paired t-test, p <
0.001). There were two dislocations, and in three patients we failed to eradicate previous infection. None required revision of the femoral stem. This technique allows instant distal fixation while promoting biological integration and restoration of bone stock. In the short term, the functional outcome is encouraging and the complication rates acceptable in this difficult group of patients.
Recent studies have shown that modulating inflammation-related
lipid signalling after a bone fracture can accelerate healing in
animal models. Specifically, decreasing 5-lipoxygenase (5-LO) activity
during fracture healing increases cyclooxygenase-2 (COX-2) expression
in the fracture callus, accelerates chondrogenesis and decreases
healing time. In this study, we test the hypothesis that 5-LO inhibition
will increase direct osteogenesis. Bilateral, unicortical femoral defects were used in rats to measure
the effects of local 5-LO inhibition on direct osteogenesis. The
defect sites were filled with a polycaprolactone (PCL) scaffold
containing 5-LO inhibitor (A-79175) at three dose levels, scaffold
with drug carrier, or scaffold only. Drug release was assessed Objectives
Methods
Using data from the Norwegian Hip Fracture Register,
8639 cemented and 2477 uncemented primary hemiarthroplasties for
displaced fractures of the femoral neck in patients aged > 70 years
were included in a prospective observational study. A total of 218
re-operations were performed after cemented and 128 after uncemented
procedures. Survival of the hemiarthroplasties was calculated using
the Kaplan-Meier method and hazard rate ratios (HRR) for revision
were calculated using Cox regression analyses. At five years the
implant survival was 97% (95% confidence interval (CI) 97 to 97)
for cemented and 91% (95% CI 87 to 94) for uncemented hemiarthroplasties.
Uncemented hemiarthroplasties had a 2.1 times increased risk of
revision compared with cemented prostheses (95% confidence interval
1.7 to 2.6, p < 0.001). The increased risk was mainly caused
by revisions for peri-prosthetic fracture (HRR = 17), aseptic loosening
(HRR = 17), haematoma formation (HRR = 5.3), superficial infection
(HRR = 4.6) and dislocation (HRR = 1.8). More intra-operative complications,
including intra-operative death, were reported for the cemented
hemiarthroplasties. However, in a time-dependent analysis, the HRR
for re-operation in both groups increased as follow-up increased. This study showed that the risk for revision was higher for uncemented
than for cemented hemiarthroplasties.
This review considers the surgical treatment
of displaced fractures involving the knee in elderly, osteoporotic patients.
The goals of treatment include pain control, early mobilisation,
avoidance of complications and minimising the need for further surgery.
Open reduction and internal fixation (ORIF) frequently results in
loss of reduction, which can result in post-traumatic arthritis
and the occasional conversion to total knee replacement (TKR). TKR
after failed internal fixation is challenging, with modest functional
outcomes and high complication rates. TKR undertaken as treatment
of the initial fracture has better results to late TKR, but does
not match the outcome of primary TKR without complications. Given
the relatively infrequent need for late TKR following failed fixation,
ORIF is the preferred management for most cases. Early TKR can be
considered for those patients with pre-existing arthritis, bicondylar
femoral fractures, those who would be unable to comply with weight-bearing restrictions,
or where a single definitive procedure is required.
We analysed the results of different strategies in the revision of primary uncemented acetabular components reported to the Norwegian Arthroplasty Register. The aim was to compare the risk of further acetabular revision after isolated liner exchange and complete component revision. The results of exchanging well-fixed components were also compared with those of exchanging loose acetabular components. The period studied was between September 1987 and April 2005. The following groups were compared: group 1, exchange of liner only in 318 hips; group 2, exchange of well-fixed components in 398; and group 3, exchange of loose components in 933. We found that the risk of a further cup revision was lower after revision of well-fixed components (relative risk from a Cox model (RR) = 0.56, 95% confidence interval 0.37% to 0.87%) and loose components (RR = 0.56, 95% confidence interval 0.39% to 0.80%), compared with exchange of the liner in isolation. The most frequent reason for a further acetabular revision was dislocation, accounting for 61 (28%) of the re-revisions. Other reasons for further revision included pain in 27 (12%), loosening in 24 (11%) and infection in 20 (9%). Re-revisions because of pain were less frequent when complete component (fixed or loose) revision was undertaken compared with isolated exchange of the liner (RR = 0.20 (95% confidence interval 0.06% to 0.65%) and RR = 0.10 (95% confidence interval 0.03% to 0.30%), respectively). The risk of further acetabular revision for infection, however, did not differ between the groups. In this study, exchange of the liner only had a higher risk of further cup revision than revision of the complete acetabular component. Our results suggest that the threshold for revising well-fixed components in the case of liner wear and osteolysis should be lowered.
We used an A significant improvement in functional weight-bearing was observed between six and 12 weeks. The significant increase in ground reaction force through the operated limb between six and 12 weeks was greater than that reported previously with morcellised graft augmented reconstructions. Histological appearance and collagen fibre orientation with bone block augmentation more closely resembled that of an intact enthesis compared with the morcellised grafting technique. Bone block augmentation of tendon-implant interfaces results in more reliable functional and histological outcomes, with a return to pre-operative levels of weight-bearing by 24 weeks.
Narrowing of the femoral neck after resurfacing arthroplasty of the hip has been described previously in both cemented and uncemented hip resurfacing. The natural history of narrowing of the femoral neck is unknown. We retrospectively measured the diameter of the femoral neck in a series of 163 Birmingham hip resurfacings in 163 patients up to a maximum of six years after operation to determine the extent and progression of narrowing. There were 105 men and 58 women with a mean age of 52 years (18 to 82). At a mean follow-up of five years, the mean Harris hip score was 94.8 (47 to 100) and the mean flexion of the hip 112.5° (80° to 160°). There was some narrowing of the femoral neck in 77% (125) of the patients reviewed, and in 27.6% (45) the narrowing exceeded 10% of the diameter of the neck. A multiple logistic regression analysis showed a significant association (chi-squared test (derived from logistic regression) p = 0.01) of narrowing with female gender and a valgus femoral neck/shaft angle. There was no significant association between the range of movement, position or size of the component or radiological lucent lines and narrowing of the neck (chi-squared test; p = 0.10 (flexion), p = 0.08 (size of femoral component), p = 0.09 (size of acetabular component), p = 0.71 (femoral component angulation), p = 0.99 (lucent lines)). There was no significant difference between the diameter of the neck at a mean of three years (2.5 to 3.5) and that at five years (4.5 to 5.5), indicating that any change in the diameter of the neck had stabilised by three years (sign rank test, p = 0.60). We conclude that narrowing of the femoral neck which is found with the Birmingham hip resurfacing arthroplasty is in most cases associated with no adverse clinical or radiological outcome up to a maximum of six years after the initial operation.
We evaluated the long-term fixation of 64 press-fit cemented stems of constrained total knee prostheses in 32 young patients with primary malignant bone tumours. Initial stable fixation, especially in rotation, was achieved by precise fit of the stem into the reamed endosteum, before cementation. Complementary fixation, especially in migration and rotation, was obtained by pressurised antibiotic-loaded cement. The mean age at operation was 33 years (13 to 61). No patient was lost to follow-up; 13 patients died and the 19 survivors were examined at a mean follow-up of 12.5 years (4 to 21). Standard revision press-fit cemented stems were used on the side of the joint which was not involved with tumour (26 tibial and six femoral), on this side there was no loosening or osteolysis and stem survival was 100%. On the reconstruction side, custom-made press-fit stems were used and the survival rate, with any cause for revision as an end point, was 88%, but 97% for loosening or osteolysis. This longevity is similar to that achieved at 20 years with the Charnley-Kerboull primary total hip replacement with press-fit cemented femoral components. We recommend this type of fixation when extensive reconstruction of the knee is required. It may also be suitable for older patients requiring revision of a total knee replacement or in difficult situations such as severe deformity and complex articular fractures.
In skeletally immature patients, resection of
bone tumours and reconstruction of the lower limb often results
in leg-length discrepancy. The Stanmore non-invasive extendible
endoprosthesis, which uses electromagnetic induction, allows post-operative
lengthening without anaesthesia. Between 2002 and 2009, 55 children
with a mean age of 11.4 years (5 to 16) underwent reconstruction
with this prosthesis; ten patients (18.2%) died of disseminated
disease and one child underwent amputation due to infection. We
reviewed 44 patients after a mean follow-up of 41.2 months (22 to
104). The mean Musculoskeletal Tumor Society score was 24.7 (8 to
30) and the Toronto Extremity Salvage score was 92.3% (55.2% to
99.0%). There was no local recurrence of tumour. Complications developed
in 16 patients (29.1%) and ten (18.2%) underwent revision. The mean length gained per patient was 38.6 mm (3.5 to 161.5),
requiring a mean of 11.3 extensions (1 to 40), and ten component
exchanges were performed in nine patients (16.4%) after attaining
the maximum lengthening capacity of the implant. There were 11 patients
(20%) who were skeletally mature at follow-up, ten of whom had equal
leg lengths and nine had a full range of movement of the hip and
knee. This is the largest reported series using non-invasive extendible
endoprostheses after excision of primary bone tumours in skeletally
immature patients. The technique produces a good functional outcome,
with prevention of limb-length discrepancy at skeletal maturity.
We report a case of spontaneous physeal growth arrest of the distal femur in a nine-year-old child with Ewing’s sarcoma of the proximal femur treated with chemotherapy and endoprosthetic replacement. Owing to the extent of disuse osteoporosis at the time of surgery, the entire intramedullary canal up to the distal femoral physis was filled with cement. Three years later, the femur remained at its pre-operative length of 19 cm. Pre-operative calculations of further growth failed to account for the growth arrest, and the initial expandable growing prosthesis inserted has been revised to a longer one in order to address the leg-length discrepancy. To our knowledge, this is the only reported case of distal femoral physeal growth arrest following cemented endoprosthetic replacement of the proximal femur.
We report the long-term results of revision total
hip replacement using femoral impaction allografting with both uncemented
and cemented Freeman femoral components. A standard design of component
was used in both groups, with additional proximal hydroxyapatite
coating in the uncemented group. A total of 33 hips in 30 patients received
an uncemented component and 31 hips in 30 patients a cemented component.
The mean follow-up was 9.8 years (2 to 17) in the uncemented group
and 6.2 years (1 to 11) in the cemented group. Revision procedures
(for all causes) were required in four patients (four hips) in the
uncemented group and in five patients (five hips) in the cemented
group. Harris hip scores improved significantly in both groups and
were maintained independently of the extent of any migration of
the femoral component within the graft or graft–cement mantle.
For the treatment of ununited fractures, we developed
a system of delivering magnetic labelled mesenchymal stromal cells
(MSCs) using an extracorporeal magnetic device. In this study, we
transplanted ferucarbotran-labelled and luciferase-positive bone
marrow-derived MSCs into a non-healing femoral fracture rat model
in the presence of a magnetic field. The biological fate of the
transplanted MSCs was observed using luciferase-based bioluminescence
imaging and we found that the number of MSC derived photons increased
from day one to day three and thereafter decreased over time. The
magnetic cell delivery system induced the accumulation of photons at
the fracture site, while also retaining higher photon intensity
from day three to week four. Furthermore, radiological and histological
findings suggested improved callus formation and endochondral ossification.
We therefore believe that this delivery system may be a promising
option for bone regeneration.
It is accepted that resurfacing hip replacement
preserves the bone mineral density (BMD) of the femur better than total
hip replacement (THR). However, no studies have investigated any
possible difference on the acetabular side. Between April 2007 and March 2009, 39 patients were randomised
into two groups to receive either a resurfacing or a THR and were
followed for two years. One patient’s resurfacing subsequently failed,
leaving 19 patients in each group. Resurfaced replacements maintained proximal femoral BMD and,
compared with THR, had an increased bone mineral density in Gruen
zones 2, 3, 6, and particularly zone 7, with a gain of 7.5% (95%
confidence interval (CI) 2.6 to 12.5) compared with a loss of 14.6%
(95% CI 7.6 to 21.6). Resurfacing replacements maintained the BMD
of the medial femoral neck and increased that in the lateral zones
between 12.8% (95% CI 4.3 to 21.4) and 25.9% (95% CI 7.1 to 44.6). On the acetabular side, BMD was similar in every zone at each
point in time. The mean BMD of all acetabular regions in the resurfaced
group was reduced to 96.2% (95% CI 93.7 to 98.6) and for the total
hip replacement group to 97.6% (95% CI 93.7 to 101.5) (p = 0.4863).
A mean total loss of 3.7% (95% CI 1.0 to 6.5) and 4.9% (95% CI 0.8
to 9.0) of BMD was found above the acetabular component in W1 and
10.2% (95% CI 0.9 to 19.4) and 9.1% (95% CI 3.8 to 14.4) medial
to the implant in W2 for resurfaced replacements and THRs respectively.
Resurfacing resulted in a mean loss of BMD of 6.7% (95% CI 0.7 to
12.7) in W3 but the BMD inferior to the acetabular component was
maintained in both groups. These results suggest that the ability of a resurfacing hip replacement
to preserve BMD only applies to the femoral side.
We evaluated the use of a stemmed acetabular component in the treatment of severe acetabular deficiency during revision and complex primary total hip arthroplasty. There were 31 hips of which 24 were revisions (20 for aseptic loosening, four for infection) and the remainder were complex primary arthroplasties. At a mean follow-up of 10.7 years (6 to 12.8), no component had been revised for aseptic loosening; one patient had undergone a revision of the polyethylene liner for wear. There was one failure because of infection. At the latest follow-up, the cumulative survival rate for aseptic loosening, with revision being the end-point, was 100%; for radiographic loosening it was 92% and for infection and radiographic loosening it was 88%. These results justify the continued use of this stemmed component for the reconstruction of severe acetabular deficiency.
Primary uncemented femoral stems reported to the Norwegian arthroplasty register between 1987 and 2005 were included in this prospective observational study. There were 11 516 hips (9679 patients) and 14 different designs of stem. Kaplan-Meier survival probabilities and Cox regression were used to analyse the data. With aseptic loosening as the end-point, all currently used designs performed excellently with survival of 96% to 100% at ten years. With the end-point as stem revision for any cause, the long-term results of the different designs varied from poor to excellent, with survival at 15 years ranging between 29% and 97%. Follow-up for longer than seven years was needed to identify some of the poorly-performing designs. There were differences between the stems; the Corail, used in 5456 hips, was the most frequently used stem with a survival of 97% at 15 years. Male gender was associated with an increased risk of revision of × 1.3 (95% confidence interval 1.05 to 1.52), but age and diagnosis had no influence on the results. Overall, modern uncemented femoral stems performed well. Moderate differences in survival between well-performing stems should be interpreted with caution since the differences may be caused by factors other than the stem itself.
Ciprofloxacin hydrochloride-loaded microspheres were prepared by a spray-drying method using pectin and chitosan. The effects of different polymers and drug ratios were investigated. The most appropriate carriers were selected by The drug was released rapidly from the pectin carrier but this was more sustained in the chitosan formulation. Chitosan microspheres loaded with ciprofloxacin hydrochloride were more effective for the treatment of osteomyelitis than equivalent intramuscular antibiotics.
A modular layered acetabular component (metal-polyethylene-ceramic) was developed in Japan for use in alumina ceramic-on-ceramic total hip replacement. Between May 1999 and July 2000, we performed 35 alumina ceramic-on-ceramic total hip replacements in 30 consecutive patients, using this layered component and evaluated the clinical and radiological results over a mean follow-up of 5.8 years (5 to 6.5). A total of six hips underwent revision, one for infection, two for dislocation with loosening of the acetabular component, two for alumina liner fractures and one for component dissociation with pelvic osteolysis. There were no fractures of the ceramic heads, and no loosening of the femoral or acetabular component in the unrevised hips was seen at final follow-up. Osteolysis was not observed in any of the unrevised hips. The survivorship analysis at six years after surgery was 83%. The layered acetabular component in our experience, has poor durability because of unexpected mechanical failures including alumina liner fracture and component dissociation.
In a series of 1304 patients (1867 knees), the results of simultaneous and staged bilateral total knee arthroplasty were compared with each other and with unilateral total knee arthroplasty. The bilateral procedures had a significantly higher rate of complications than unilateral procedures, almost entirely because of thromboembolic problems. However, this did not correspond to an increase in mortality. If a bilateral procedure was indicated, then a simultaneous procedure had no increased risk over a staged procedure. There was no increase in cardiovascular complications, the rate of deep-vein thrombosis or pulmonary embolism or mortality. The rate of infection was lower with a bilateral procedure and the overall revision rate was less than 1% in all groups. The prosthesis functioned as well in all groups in the medium and longer term periods. We feel that simultaneous bilateral total knee arthroplasty is a safe and successful procedure when compared with a staged bilateral procedure. It also has the added benefit of single anaesthetic, reduced costs and decreased total recovery time when compared to a staged bilateral procedure. For these reasons it should be considered as an option in the presence of bilateral knee joint disease.
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.