Constrained acetabular components are a useful adjunct for the potentially unstable hip arthroplasty. There have been concerns over implant failure and early acetabular component loosening secondary to the increased implant constraint. We report the results of a constrained ace-tabular component used as treatment for dislocating hips and as prophylaxis against dislocation in high risk primary and revision hip arthroplasty. At average 3.1 years follow-up only one insert of eighty-nine inserted had failed. No cups have demonstrated radiographic or clinical evidence of loosening. We conclude this implant is safe and effective for both the prevention and treatment of hip instability. To review the effectiveness and durability of a constrained acetabular component used to treat and prevent recurrent dislocation after total hip arthroplasty Constrained acetabular components of this type provide both an excellent treatment and preventative option in total hip arthroplasty. There is no evidence of accelerated cup loosening and the implant failure rate remains acceptable despite the increased constraint. Constrained acetabular components have been mainly used as a salvage option for dislocating hip arthroplasty. There have been concerns over implant failure and early acetabular component loosening secondary to the increased implant constraint. Use of this implant can prevent dislocation in high risk patient groups (eg: revision surgery) without compromising implant longevity. This significantly reduces the potential morbidity associated with hip instability. Eighty-nine patients received the tripolar constrained acetabular component. Fifteen were inserted for recurrent dislocation whilst seventy-two were inserted in patients felt to be at high risk of dislocation (forty-nine for intra-operative instability at revision surgery, twenty-five for primary THA in patients with poor compliance, neurological conditions or deficient abductor mechanism). One implant failed by component dissociation at eighteen months. All other recurrent dislocators remained stable. There was no evidence of accelerated component loosening at medium term review (range twelve – eighty three months, average thirty-seven months) Radiographic and clinical data was prospectively collected on eighty-nine patients who had the constrained acetabular component inserted.
Controversy continues to exist regarding the choice of a cementless femoral component in a primary total hip arthroplasty. Both proximally coated tapered stems and fully coated cylindrical stems have excellent clinical results. The incidence of both thigh pain and proximal femoral stress shielding and multiple validated outcome measures were evaluated in a prospective randomized clinical trial with a minimum of two year follow-up comparing a proximally coated tapered femoral stem to a fully coated cylindrical femoral stem. A prospective randomized clinical trial (RCT) was performed comparing a cylindrical cobalt chrome fully coated femoral stem (Prodigy, Depuy, Warsaw, IN) to a tapered, titanium, proximally porous coated stem (Synergy, Smith &
Nephew, Memphis, TN) with respect to thigh pain, femoral stress shielding and multiple outcome measures. One hundred and ninety-four patients were enrolled and evaluations were performed pre-operatively, three months, six months and annually. Multiple outcome measures (Harris Hip Score, SF12, WOMAC, Patient Satisfaction Questionnaire, Thigh Pain Questionnaire) were obtained. Sixty-one of these patients were randomized to receive a bone density scan pre-operatively, two weeks post-operatively, six months and annually. Twelve patients were unavailable for two-year follow-up, leaving one hundred and eighty-two patients evaluated. No significant differences were demonstrated in thigh pain incidence or the multiple outcome measures. Bone density scans demonstrated significantly greater bone density (p<
0.005) in the tapered stem versus the cylindrical stem patients at two-week evaluations from distal femoral reaming. Both stem designs demonstrated statistically significant bone loss in Gruen zones one, six, seven between the two-week and one and two-year evaluations. There were no differences between stem designs although the Prodigy stem demonstrated trends towards greater bone loss in Gruen zones six and seven. This prospective RCT demonstrated no difference in thigh pain incidence and multiple outcome measures between patients receiving a proximally coated tapered versus a fully coated cylindrical femoral component. Both stem designs demonstrated statistically significant proximal femoral bone loss between the post-operative and two-year evaluations; however, there were no differences between stem designs.
This Blinded Randomized Clinical Trial outlines: how peri-articular intra-operative multimodal analgesia significantly reduces post-operative analgesia requirement. Sixty-four patients undergoing total knee replacement were randomised to receive a peri-articular intra-operative injection containing ropivacaine, ketorolac, epimorphine and epinephrine or nothing. Patients who received the injection demonstrated greater satisfaction and pain relief. Finally, patients in the injected group did not show any signs of cardio and central nervous system toxicity. Post-operative analgesia can be associated with troublesome side effects. Good peri-operative analgesia facilitates rehabilitation, improves patient satisfaction and may reduce hospital stay. The purpose of this study was to assess a novel cocktail for peri-articular analgesia after total knee replacement. Sixty-four patients undergoing total knee replacement were randomised to receive a peri-articular intra-operative injection containing ropivacaine, ketorolac, epimorphine and epinephrine or nothing. The anaesthetic analgesic regime was standardised. All patients received patient controlled analgesia (PCA) for twenty-four hours post surgery, followed by standard analgesia. VAS pain scores during activity and at rest and patient satisfaction scores were recorded pre and post operatively and at six week follow up. PCA consumption and overall analgesic requirement were measured. PCA use at six, twelve and over twenty-four hours post surgery was significantly less in patients receiving the injection (p<
0.01, p=0.016, p<
0.01). Patient satisfaction in PACU and four hours post operation was greater (p=0.016, p=0.013). VAS for pain during activity in PACU and at four hours were significantly less (p=0.04, p=0.007) in the injected group. The average ROM at six weeks was no different. Overall hospital stay and the incidence of wound complications were not different between the two groups. Peri-articular intra-operative multimodal analgesia significantly reduces post-operative analgesia requirement. Patient satisfaction and pain relief is greater in the injection group. No cardio and central nervous system toxicity was observed. Our novel cocktail of ketorolac, epimorphine, epinephrine and ropivacaine provides superior pain relief with no adverse side effects.
Despite favourable wear characteristics of compression molded HMWPE in vitro preliminary data show no statistical difference in wear between RAM extruded HMWPE and compression moulded polyethylene. This study reviews AP and lateral radiographs for wear using the Martell technique at two, five years and maximum follow up (mean 88.2 months). Reduced implant survivorship due to aseptic loosening has prompted research into alternative bearing materials. Simulator testing is useful but clinical studies are the gold standard to evaluate the wear characteristics of new bearing materials. On hundred and twelve patients matched for sex, age, body mass index, primary pathology, Charnley grade, and follow up underwent uncemented total hip replacement using an identical implant. Group One (sixty-four patients) had a RAM extruded liner (GUR 4150 HP) and Group Two (forty-eight patients) had a compression molded liner (Montell H 1900). HMWPE sterilisation regimes were identical. AP and lateral radiographs were analysed for wear using the Martell technique at two, five years and maximum follow up (mean 88.2 months). Preliminary data show a linear and volumetric wear rate in Group One of 0.067 mm/yr and 26 mm3/year respectively between two years to maximum follow up. Similarly, the wear rates for Group Two were 0.132 mm/yr and 45 mm3/year respectively. There was no statistical difference in acetabular osteolysis between Group One (16.3%) and Group Two (15%) patients at maximum follow up. Despite favourable wear characteristics of compression molded HMWPE in vitro preliminary data show no statistical difference in wear between RAM extruded HMWPE and compression moulded polyethylene. Quality of the wear debris is more likely to be important in producing aseptic loosening than actual wear rate.
T cells have been implicated in the pathogenesis of osteolysis. The goal of this study was to compare the ratios of CD4+ T cell populations in total hip arthroplasty (THA) patients with and without osteolysis. We found no significant differences in the frequency of peripheral blood CD4+CD25+ regulatory and effector T cells, serum IL-10 and TGF-β concentrations, and immuno-suppressive ability of regulatory T cells from patients with osteoarthritis prior to THA, and THA patients with and without radiographic evidence of osteolysis. CD4+ T cells are critical in regulating immune-mediated conditions. This study compared the frequency of CD4+ T cell subpopulations in the peripheral blood of patients with and without osteolysis following total hip arthroplasty (THA). Numbers of CD4+CD25hi regulatory T cells, CD4+CD25moderate effector T cells, and CD4+CD25+ T cells in the peripheral blood of thirty patients with osteoarthritis prior to primary THA, thirty patients with asymptomatic THAs and no radiographic evidence of osteolysis, nineteen patients with asymptomatic THAs with radiographic evidence of early osteolysis (not requiring revision surgery) and nine patients scheduled for revision THA for osteolysis were determined by flow cytometry. Serum IL-10 and TGF-β levels were measured using ELISA kits. Results were compared by t-test and rank sum test. CD4+ CD25hi regulatory T cells and CD4+ CD25neg T cells were isolated from blood using a MACS cell isolation kit, co-cultured for three days, and T cell proliferation determined by [3H]-thy-midine uptake. The frequency of CD4+CD25hi regulatory T cells, CD4+CD25moderate effector T cells, and CD4+CD25+ T cells were similar in each study group. Regulatory T cells from patients with and without osteolysis had a normal functional ability to inhibit CD4+ T cell proliferation. Serum levels of the regulatory T cell-derived cytokines IL-10 and TGF-β were also comparable between groups. Our data suggests that CD4+ T cell immune responses are normal in THA regardless of the level of osteolysis, in contrast to previous studies that have implicated T cell hypersensitivity in the pathogenesis of osteolysis surrounding THA.
Fifty-one prospectively followed Contour_ acetabular reconstruction cages, inserted through the direct lateral approach, were reviewed at three years minimum follow-up (range 3 to 6.4 yrs.). To date, four reoperations were required (two each for sepsis and instability) with no failures due to aseptic loosening. The Kaplan-Meier Survival Rate for any reoperation was 87% at 6.4 years. Short to mid-term follow-up of a single type of acetabular reconstruction cage, inserted through the lateral approach, demonstrated this to be a successful reconstruction option in the management of large acetabular bone defects. This study reports the mid-term results of a single design of acetabular reconstruction cage inserted through the direct lateral approach. At minimum three years follow-up (range 3 to 6.4 yrs.), there were no failures due to aseptic loosening with only four of fifty-one cases requiring reoperation (two sepsis, two instability). This review supports the use of the reconstruction cage, inserted through the lateral approach, for large defects that cannot be managed with a hemispherical porous implant. The use of the reconstruction cage in our center is reserved for large defects that cannot be managed with a hemispherical porous implant because of insufficient bone stock for initial implant stability and/or host bone contact for in-growth. Fifty-one consecutive prospectively followed Contour_ (Smith and Nephew) acetabular reconstruction cages, inserted through the direct lateral approach, were reviewed at three years minimum follow-up (range 3 to 6.4 yrs.). The majority of cases were AAOS Type Three and Four defects in which morsellized allograft was used in forty-nine cases and structural graft in three cases. Harris hip scores improved from 32.1±17.8 pre-op to 65.3±24.1 at most recent follow-up. Defining any acetabular reoperation as a failure, four of the fifty-one cages were considered to have failed giving a Kaplan-Meier Cumulative Survival Rate of 87% at 6.41 years. Two reoperations were for recurrent dislocation and the other two for sepsis. None of the fifty-one cages have been revised for aseptic loosening to date.
The timing of liner exchange for retroacetabular oste-olysis in THA remains uncertain. Liner exchange should be done before the shell becomes loose. The purpose of this study was to determine the radiographic quantity of osteolysis that will predict impending loosening of the cementless shell. Osteolytic lesions were quantified radiographically using three different measures. Implant stability was confirmed intraoperatively. Percent of shell circumference with surrounding osteolysis appears to be more predictive of cementless shell loosening than the area of osteolysis. When greater than fifty percent of the shell circumference has osteolysis on AP or lateral films, liner exchange is necessary. The timing of liner exchange for retroacetabular osteolysis in cementless THA remains uncertain. Liner exchange should be done before the shell becomes loose. To determine the radiographic quantity of osteolysis that will predict impending loosening of the cementless shell. Osteolytic areas differ between loose and stable shells. Between 1992 to 2002, seventy-one cementless shells of the same design were revised at our institution; forty-six were for aseptic retroacetabular osteolysis. Radiographs and a computer-assisted technique were used to quantify osteolytic areas and percent of shell circumference associated with lesions. Implant stability was confirmed intraoperatively. Of twenty-six stable and twenty loose shells, the average area of osteolysis on AP radiographs showed no significant difference (Stable 591mm2, Loose 630 mm2, p greater than 0.05); whereas, lateral radiographs demonstrated a significant difference (Stable 546 mm2, Loose 837 mm2, p 0.05). The percentage of shell circumference with associated osteolysis on AP and lateral films demonstrated a significant difference (AP: Stable 60, Loose 75, p 0.042; LATERAL: Stable 49, Loose73, p 0.016). Diagnostic criteria of fifty percent shell circumference associated with osteolysis on AP films has sensitivity 1, specificity 0.27 while the same criteria on lateral films has sensitivity 0.84, specificity 0.54 for shell loosening. Percent of shell circumference with surrounding oste-olysis appears to be more predictive of cementless shell loosening than the area of osteolysis. When greater than fifty percent of the shell circumference has osteolysis on AP or lateral films, liner exchange is necessary.
Purpose: To determine the radiographic quantity of osteolysis that will predict impending loosening of the cementless shell. Hypothesis: Osteolytic areas differ between loose and stable shells.
Our aim was to evaluate the functional outcome of extensile revision knee exposure techniques. 166 revision total knee arthroplasties requiring an extensile exposure with 2 year minimum follow-up were prospectively studied {81 rectus snips (RS), 42 tibial tubercle osteotomies (TTO), and 43 quadriceps turn-downs (QT)}. Patients were clinically evaluated for knee society score, range of motion (ROM) and extensor lag comparing pre-op and 24 month follow-up appointment findings. Radiological evidence of avascular necrosis (AVN) pre &
post operation was recorded. The TTO group was further examined for proximal migration of the tubercle post op. Pre-operative knee motion (75° &
71°) and knee scores (74 &
70) were lower in revision total knee arthroplasties requiring QT &
TTO than those requiring a RS (91° &
84). Post op flexion and knee scores were greater in the RS group (102° &
131) than in the QT (81° &
114) and TTO (84° &
111) groups in whom there was no significant difference. Avascular necrosis of the patella was most commonly seen following QT. In both QT &
TTO groups performing a lateral release was significantly associated with AVN of the patella. Extensor lag (>
10°) was seen only in the QT &
TTO groups (11% &
8%) in whom there was no significant difference. Tubercle escape (>
2mm) in the TTO group was significantly greater (54%) in those where circlage wires only had been used than in those where a proximal transfixation wire was used (11%). In conclusion, both QT &
TTO groups had similarly poor knee scores &
ROM pre &
post operation. AVN of the patella for both groups was similar and significantly associated with performing a lateral release. Finally we would conclude that the use of a through wire significantly reduces tubercle escape in TTO fixation.