Pelvic discontinuity with associated bone loss is a complex challenge in acetabular revision surgery. Reconstruction using ilio-ischial cages combined with trabecular metal acetabular components and morsellised bone (the component-cage technique) is a relatively new method of treatment. We reviewed a consecutive series of 26 cases of acetabular revision reconstructions in 24 patients with pelvic discontinuity who had been treated by the component-cage technique. The mean follow-up was 44.6 months (24 to 68). Failure was defined as migration of a component of >
5 mm. In 23 hips (88.5%) there was no clinical or radiological evidence of loosening at the last follow-up. The mean Harris hip score improved significantly from 46.6 points (29.5 to 68.5) to 76.6 points (55.5 to 92.0) at two years (p <
0.001). In three hips (11.5%) the construct had migrated at one year after operation. The complications included two dislocations, one infection and one partial palsy of the peroneal nerve. Our findings indicate that treatment of pelvic discontinuity using the component-cage construct is a reliable option.
Bone surface strains were measured in cadaver femora during loading prior to and after resurfacing of the hip and total hip replacement using an uncemented, tapered femoral component. In vitro loading simulated the single-leg stance phase during walking. Strains were measured on the medial and the lateral sides of the proximal aspect and the mid-diaphysis of the femur. Bone surface strains following femoral resurfacing were similar to those in the native femur, except for proximal shear strains, which were significantly less than those in the native femur. Proximomedial strains following total hip replacement were significantly less than those in the native and the resurfaced femur. These results are consistent with previous clinical evidence of bone loss after total hip replacement, and provide support for claims of bone preservation after resurfacing arthroplasty of the hip.
The management of bone loss in revision replacement of the knee remains a challenge despite an array of options available to the surgeon. Bone loss may occur as a result of the original disease, the design of the prosthesis, the mechanism of failure or technical error at initial surgery. The aim of revision surgery is to relieve pain and improve function while addressing the mechanism of failure in order to reconstruct a stable platform with transfer of load to the host bone. Methods of reconstruction include the use of cement, modular metal augmentation of prostheses, custom-made, tumour-type or hinged implants and bone grafting. The published results of the surgical techniques are summarised and a guide for the management of bone defects in revision surgery of the knee is presented.
This prospective study presents the ten-year (5 to 16) clinical and radiological results of 55 primary total hip replacements (THR) using a cementless modular femoral component (S-ROM). All patients had a significant anatomical abnormality which rendered the primary THR difficult. The mean Harris hip score was 36 (12 to 72) pre-operatively, 83 (44 to 100) at five years, and 85 (45 to 99) at ten years. The Western Ontario and McMaster Universities osteoarthritis index (WOMAC) and short-form (SF)-12 scores were recorded from the year 2000. The mean SF-12 score at five years after surgery was 45.24 (22.74 to 56.58) for the physical component and 54.14 (29.20 to 66.61) for the mental component. By ten years the SF-12 scores were 42.86 (21.59 to 58.95) and 51.03 (33.78 to 61.40), respectively. The mean WOMAC score at five years post-operatively was 25 (0 to 59), and at ten years was 27 (2 to 70). No femoral components were radiologically loose, although five had osteolysis in Gruen zone 1, three had osteolysis in zone 7, and two showed osteolysis in both zones 1 and 7. No osteolysis was observed around or distal to the prosthetic sleeve. No femoral components were revised, although three hips underwent an acetabular revision and two required a liner exchange. At a mean of ten years’ follow-up the S-ROM femoral component implanted for an anatomically difficult primary THR has excellent clinical and radiological results.
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.
A 34-year-old woman with a benign form of osteopetrosis developed osteoarthritis of the hip. In order to avoid the difficulties associated with inserting the femoral component of a conventional total hip arthroplasty, a hybrid metal-on-metal resurfacing was performed. There were several technical challenges associated with the procedure, including the sizing of the component, press-fit fixation of the acetabular component and femoral head preparation, as well as trying to avoid a fracture. No surgical complication occurred. After more than a year following surgery, the patient showed excellent clinical function and remained satisfied with the outcome. We conclude that the hybrid metal-on-metal resurfacing arthroplasty represents a valuable option for the treatment of patients with osteopetrosis and secondary hip osteoarthritis.
In this study we present our experience with
four generations of uncemented total knee arthroplasty (TKA) from Smith
&
Nephew: Tricon M, Tricon LS, Tricon II and Profix, focusing
on the failure rates correlating with each design change. Beginning
in 1984, 380 Tricon M, 435 Tricon LS, 305 Tricon 2 and 588 Profix
were implanted by the senior author. The rate of revision for loosening
was 1.1% for the Tricon M, 1.1% for the Tricon LS, 0.5% for the
Tricon 2 with a HA coated tibial component, and 1.3% for the Profix
TKA. No loosening of the femoral component was seen with the Tricon
M, Tricon LS or Tricon 2, with no loosening seen of the tibial component
with the Profix TKA. Regarding revision for wear, the incidence
was 13.1% for the Tricon M, 6.6% for the Tricon LS, 2.3% for the
Tricon 2, and 0% for the Profix. These results demonstrate that
improvements in the design of uncemented components, including increased
polyethylene thickness, improved polyethylene quality, and the introduction
of hydroxyapatite coating, has improved the outcomes of uncemented
TKA over time.
Failure of fixation is a common problem in the treatment of osteoporotic fractures around the hip. The reinforcement of bone stock or of fixation of the implant may be a solution. Our study assesses the existing evidence for the use of bone substitutes in the management of these fractures in osteoporotic patients. Relevant publications were retrieved through Medline research and further scrutinised. Of 411 studies identified, 22 met the inclusion criteria, comprising 12 experimental and ten clinical reports. The clinical studies were evaluated with regard to their level of evidence. Only four were prospective and randomised. Polymethylmethacrylate and calcium-phosphate cements increased the primary stability of the implant-bone construct in all experimental and clinical studies, although there was considerable variation in the design of the studies. In randomised, controlled studies, augmentation of intracapsular fractures of the neck of the femur with calcium-phosphate cement was associated with poor long-term results. There was a lack of data on the long-term outcome for trochanteric fractures. Because there were only a few, randomised, controlled studies, there is currently poor evidence for the use of bone cement in the treatment of fractures of the hip.
The Cementless Oxford Unicompartmental Knee Replacement
(OUKR) was developed to address problems related to cementation,
and has been demonstrated in a randomised study to have similar
clinical outcomes with fewer radiolucencies than observed with the
cemented device. However, before its widespread use it is necessary
to clarify contraindications and assess the complications. This
requires a larger study than any previously published. We present a prospective multicentre series of 1000 cementless
OUKRs in 881 patients at a minimum follow-up of one year. All patients
had radiological assessment aligned to the bone–implant interfaces
and clinical scores. Analysis was performed at a mean of 38.2 months
(19 to 88) following surgery. A total of 17 patients died (comprising
19 knees (1.9%)), none as a result of surgery; there were no tibial
or femoral loosenings. A total of 19 knees (1.9%) had significant
implant-related complications or required revision. Implant survival
at six years was 97.2%, and there was a partial radiolucency at
the bone–implant interface in 72 knees (8.9%), with no complete radiolucencies.
There was no significant increase in complication rate compared
with cemented fixation (p = 0.87), and no specific contraindications
to cementless fixation were identified. Cementless OUKR appears to be safe and reproducible in patients
with end-stage anteromedial osteoarthritis of the knee, with radiological
evidence of improved fixation compared with previous reports using
cemented fixation. Cite this article:
The Motec cementless modular metal-on-metal ball-and-socket
wrist arthroplasty was implanted in 16 wrists with scaphoid nonunion
advanced collapse (SNAC; grades 3 or 4) and 14 wrists with scapholunate
advanced collapse (SLAC) in 30 patients (20 men) with severe (grades
3 or 4) post-traumatic osteoarthritis of the wrist. The mean age of
the patients was 52 years (31 to 71). All prostheses integrated
well radiologically. At a mean follow-up of 3.2 years (1.1 to 6.1)
no luxation or implant breakage occurred. Two wrists were converted
to an arthrodesis for persistent pain. Loosening occurred in one
further wrist at five years post-operatively. The remainder demonstrated close
bone–implant contact. The clinical results were good, with markedly
decreased Disabilities of the Arm Shoulder and Hand (DASH) and pain
scores, and increased movement and grip strength. No patient used
analgesics and most had returned to work. Good short-term function was achieved using this wrist arthroplasty
in a high-demand group of patients with post-traumatic osteoarthritis.
During revision total hip replacement using morcellised compacted bone allograft, 16 patients were randomised to receive a graft which had been rinsed in either an ibandronate solution or in saline. Patients were assessed by dual energy x-ray absorptiometry after operation and at 3, 6, 12 and 24 months. A region of interest between the tip of the femoral stem and the distal plastic plug was chosen to measure the changes in bone density over time. The study was double-blinded. In all the control patients the bone density decreased during the first three months and then remained constant at this lower level. A large proportion of the mass of the bone graft was lost. In contrast, all patients with grafts treated with bisphosphonate showed a slight increase in bone density. The difference between the groups was highly significant at all points in time. We conclude that rinsing the graft in a bisphosphonate solution prevents its resorption and may therefore reduce the risk of mechanical failure. The treatment is simple, inexpensive, and appears virtually free of risk.
An experimental sheep model was used for impaction allografting of 12 hemiarthroplasty femoral components placed into two equal-sized groups. In group 1, a 50:50 mixture of ApaPore hydroxyapatite bone-graft substitute and allograft was used. In group 2, ApaPore and allograft were mixed in a 90:10 ratio. Both groups were killed at six months. Ground reaction force results demonstrated no significant differences (p >
0.05) between the two groups at 8, 16 and 24 weeks post-operatively, and all animals remained active. The mean bone turnover rates were significantly greater in group 1, at 0.00206 mm/day, compared to group 2 at 0.0013 mm/day (p <
0.05). The results for the area of new bone formation demonstrated no significant differences (p >
0.05) between the two groups. No significant differences were found between the two groups in thickness of the cement mantle (p >
0.05) and percentage ApaPore-bone contact (p >
0.05). The results of this animal study demonstrated that a mixture of ApaPore allograft in a 90:10 ratio was comparable to using a 50:50 mixture.
Our aim in this prospective study was to compare the bone mineral density (BMD) around cementless acetabular and femoral components which were identical in geometry and had the same alumina modular femoral head, but differed in regard to the material of the acetabular liners (alumina ceramic or polyethylene) in 50 patients (100 hips) who had undergone bilateral simultaneous primary total hip replacement. Dual energy X-ray absorptiometry scans of the pelvis and proximal femur were obtained at one week, at one year, and annually thereafter during the five-year period of the study. At the final follow-up, the mean BMD had increased significantly in each group in acetabular zone I of DeLee and Charnley (20% (15% to 26%), p = 0.003), but had decreased in acetabular zone II (24% (18% to 36%) in the alumina group and 25% (17% to 31%) in the polyethylene group, p = 0.001). There was an increase in the mean BMD in zone III of 2% (0.8% to 3.2%) in the alumina group and 1% (0.6% to 2.2%) in the polyethylene group (p = 0.315). There was a decrease in the mean BMD in the calcar region (femoral zone 7) of 15% (8% to 24%) in the alumina group and 14% (6% to 23%) in the polyethylene group (p <
0.001). The mean bone loss in femoral zone 1 of Gruen et al was 2% (1.1% to 3.1%) in the alumina group and 3% (1.3% to 4.3%) in the polyethylene group (p = 0.03), and in femoral zone 6, the mean bone loss was 15% (9% to 27%) in the alumina group and 14% (11% to 29%) in the polyethylene group compared with baseline values. There was an increase in the mean BMD on the final scans in femoral zones 2 (p = 0.04), 3 (p = 0.04), 4 (p = 0.12) and 5 (p = 0.049) in both groups. There was thus no significant difference in the bone remodelling of the acetabulum and femur five years after total hip replacement in those two groups where the only difference was in the acetabular liner.
We studied a consecutive series of 285 uncemented total hip replacements in 260 patients using the Taperloc femoral component and the T-Tap acetabular component. The outcome of every hip was determined in both living and deceased patients. A complete clinical and radiological follow-up was obtained for 209 hips in 188 living patients, followed for a mean of 14.5 years (10 to 18.9). They were divided into two groups, obese and non-obese, as determined by their body mass index. There were 100 total hip replacements in 89 patients in the obese cohort (body mass index ≥ 30 kg/m2), and 109 in 99 non-obese (body mass index <
30 kg/m2) patients. A subgroup analysis of 31 patients of normal weight (body mass index 20 kg/m2 to 25 kg/m2) (33 hips) and 26 morbidly obese patients (body mass index ≥ 35 kg/m2) (30 hips) was also carried out. In the obese group five femoral components (5%) were revised and one (1%) was loose by radiological criteria. Femoral cortical osteolysis was seen in eight hips (8%). The acetabular component was revised in 57 hips (57%) and a further 17 (17%) were loose. The mean Harris hip score improved from 52 (30 to 66) pre-operatively to 89 (49 to 100) at final follow-up. Peri-operative complications occurred in seven patients (7%). In the non-obese group six (6%) femoral components were revised and one (1%) was loose. Femoral cortical osteolysis occurred in six hips (6%). The acetabular component was revised in 72 hips (66%) and a further 18 (17%) were loose. The mean Harris hip score increased from 53 (25 to 73) prior to surgery to 89 (53 to 100) at the time of each patient’s final follow-up radiograph. No statistically significant difference was identified between the obese and non-obese patients with regards to clinical and radiological outcome or complications. The subgroup analysis of patients of normal weight and those who were morbidly obese showed no statistically significant difference in the rate of revision of either component. Our findings suggest there is no evidence to support withholding total hip replacement from obese patients with arthritic hips on the grounds that their outcome will be less satisfactory than those who are not obese.
Between January 1984 and January 1986, 131 porous-coated anatomic total hip replacements were performed in 119 consecutive patients. Of these, 100 patients (110 hips) who were alive at a minimum of 18 years after replacement were included in the study. The mean age of the patients at surgery was 48.4 years and that of surviving patients at the latest follow-up was 67.8 years. The mean duration of the clinical and radiological follow-up was 19.4 years (18 to 20). The mean Harris hip score initially improved from 55 points before to 95 points at two years after operation, but subsequently decreased to 91 points after six years, 87 points after 11.2 years, and 85 points after 19.4 years. At the final follow-up, 23 hips (18%) of the entire cohort and 21% of survivors had undergone revision because of loosening or osteolysis of the acetabular component and eight hips (6%) of the entire cohort and 7% of survivors for loosening or osteolysis of the femoral component. Only four femoral components (4%) were revised for isolated aseptic loosening without osteolysis and two (2%) for recurrent dislocation. On the basis of these long-term results, the porous-coated anatomic femoral component survived for a minimum of 18 years after operation while the acetabular component was less durable. The findings identify the principles of uncemented joint replacement which can be applied to current practice.
We carried out a prospective investigation into
the radiological outcomes of uncemented Oxford medial compartment
unicondylar replacement in 220 consecutive patients (231 knees)
performed in a single centre with a minimum two-year follow-up.
The functional outcomes using the mean Oxford knee score and the
mean high-activity arthroplasty score were significantly improved
over the pre-operative scores (p <
0.001). There were 196 patients
with a two-year radiological examination performed under fluoroscopic
guidance, aiming to provide images acceptable for analysis of the
bone–implant interface. Of the six tibial zones examined on each
knee on the anteroposterior radiograph, only three had a partial
radiolucent line. All were in the medial aspect of the tibial base plate
(zone 1) and all measured <
1 mm. All of these patients were
asymptomatic. There were no radiolucent lines seen around the femoral
component or on the lateral view. There was one revision for loosening
at one year due to initial inadequate seating of the tibial component.
These results confirm that the early uncemented Oxford medial unicompartmental
compartmental knee replacements were reliable and the incidence
of radiolucent lines was significantly decreased compared with the
reported results of cemented versions of this implant. These independent
results confirm those of the designing centre.
We investigated the effect of stimulation with a pulsed electromagnetic field on the osseointegration of hydroxyapatite in cortical bone in rabbits. Implants were inserted into femoral cortical bone and were stimulated for six hours per day for three weeks. Electromagnetic stimulation improved osseointegration of hydroxyapatite compared with animals which did not receive this treatment in terms of direct contact with the bone, the maturity of the bone and mechanical fixation. The highest values of maximum push-out force (Fmax) and ultimate shear strength (σu) were observed in the treated group and differed significantly from those of the control group at three weeks (Fmax; p <
0.0001; σu, p <
0.0005).
We reviewed 59 bone graft substitutes marketed
by 17 companies currently available for implantation in the United Kingdom,
with the aim of assessing the peer-reviewed literature to facilitate
informed decision-making regarding their use in clinical practice.
After critical analysis of the literature, only 22 products (37%)
had any clinical data. Norian SRS (Synthes), Vitoss (Orthovita),
Cortoss (Orthovita) and Alpha-BSM (Etex) had Level I evidence. We question
the need for so many different products, especially with limited
published clinical evidence for their efficacy, and conclude that
there is a considerable need for further prospective randomised
trials to facilitate informed decision-making with regard to the
use of current and future bone graft substitutes in clinical practice. Cite this article:
Persistent groin pain after seemingly successful
total hip replacement (THR) appears to have become more common.
Recent studies have indicated a high incidence after metal-on-polyethylene
and metal-on-metal conventional THR and it has been documented in
up to 18% of patients after metal-on-metal resurfacing. There are many
causes, including acetabular loosening, stress fracture, and iliopsoas
tendonitis and impingement. The evaluation of this problem requires
a careful history and examination, plain radiographs and an algorithmic approach
to special diagnostic imaging and tests. Non-operative treatment
is not usually successful. Specific operative treatment depending
on the cause of the pain usually involves revision of the acetabular
component, iliopsoas tenotomy or other procedures, and is usually
successful. Here, an appropriate algorithm is described.
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.