We report ten-year clinical and radiological follow-up data for the Sigma Press Fit Condylar total knee replacement system (Sigma PFC TKR). Between October 1998 and October 1999 a total of 235 consecutive PFC Sigma TKRs were carried out in 203 patients. Patients were seen at a specialist nurse-led clinic seven to ten days before admission and at six and 18 months, three, five and eight to ten years after surgery. Data were recorded prospectively at each clinic visit. Radiographs were obtained at the five- and eight- to ten-year follow-up appointments. Of the 203 patients, 147 (171 knees) were alive at ten years and 12 were lost to follow-up. A total of eight knees (3.4%) were revised, five for infection and three to change the polyethylene insert. The survival at ten years with an endpoint of revision for any reason was 95.9%, and with an endpoint of revision for aseptic failure was 98.7%. The mean American Knee Society Score (AKSS) was 79 (10 to 99) at eight to ten years, compared with 31 (2 to 62) pre-operatively. Of 109 knee with radiographs reviewed, 47 knees had radiolucent lines but none showed evidence of loosening. Cite this article: Bone Joint J 2013;95-B:177–80

The DuPuy Sigma total knee arthroplasty (TKA) is a modification of the well-established Press Fit Condylar (PFC) TKA and is used extensively in the UK and worldwide. This study reports the first 10-year clinical and radiological follow-up data for the Sigma PFC. A total of 235 consecutive Sigma TKAs were performed in 203 patients between October 1998 and October 1999, in our unit. Patients were seen at a specialist nurse-led clinic 1 week before admission and at 6 months, 18 months, 3 years, 5 years and 7-10 years after surgery. Data was recorded prospectively at each clinic visit. Of 235 knees, 171 (147 patients) were alive at 10 years. Twelve were lost to follow up. Eight knees (3.4%) were revised; four for infection and four underwent isolated change of polyethylene insert. Ten-year survival with an end point of revision for any reason was 95.9%, and with an endpoint of revision for aseptic failure was 98.7%. The mean American Knee Society score was 62 at 8-10 years compared with 31 out of 100 pre-operatively. Our results show that the PFC Sigma knee arthroplasty performs well over the first 10 years post-implantation

This study reports the first 10-year clinical and radiological follow-up data for the Sigma PFC. The DuPuy Sigma total knee arthroplasty (TKA) is a modification of the well established Press Fit Condylar (PFC) TKA and is used extensively in the UK and worldwide. It is the most commonly used TKA in England and Wales, where it accounts for 34% of all primary TKA. A total of 235 consecutive Sigma TKAs were performed in 203 patients between October 1998 and October 1999, in our unit. Patients were seen at a specialist nurse led clinic 7 to 10 days before admission and at 6 months, 18 months, 3 years, 5 years and 7-10 years after surgery. Data was recorded prospectively at each clinic visit. Radiographs were obtained at the 5 year and 8-10 year follow-up appointment. Of 235 knees 171 (147 patients) were alive at 10 years. Twelve were lost to follow up. Nine knees (3.8%) were revised; five for infection and four underwent change of polyethylene insert. Ten-year survival with and end point of revision for any reason was 95.9%, and with and endpoint of revision for aseptic failure was 98.7%. The mean American Knee Society score was 62 at 8-10 years compared with 31 out of 100 pre-operatively. Of 109 radiographs, 47 knees had radiolucent lines but none showed radiological evidence of loosening. Our results show that the PFC Sigma knee arthroplasty performs well over the first 10 years post implantation

The Morscher press fit acetabular component is a monobloc cup with the polyethylene bonded directly to a titanium mesh shell. There is little published data on the longevity of the Morscher cup apart from the designer’s series. It has been quite widely used in New Zealand since its introduction in 1993. The aim of this retrospective study was to provide an independent mid-term audit of the results of this cup in the New Zealand population. A retrospective review was undertaken of all Morscher cups implanted at Dunedin Public Hospital or Mercy Hospital by 5 orthopaedic surgeons between 1994 and 1998 with a minimum follow-up of seven years. Clinical and radiological survey was performed with standardised scoring systems. A new method for measuring linear cup wear was developed due to the unusual geometry of the Morscher cup. 136 hips were replaced in 121 patients during the study period 101 were performed in private and 35 in public. Our follow up ranged from 7 to 11 years (mean 8.69). There were 73 males (85 hips) and 48 females (51 hips). The average age of the patients was 57.5yrs (SO 24.97). Pre operatively the mean Merle d’Aubigne score was 9.4 (SO 4.02) and post operatively it was 17.4 (SO 1.58 (p< 0.0001). There were 2 early revisions: one at 3 days for instability post-operatively and one for an unrecognised intra-operative femoral fracture. One hip required a two stage revision for deep infection at 3 years. Two hips have been revised for polyethylene wear and osteolysis at 7 yrs and 9 yrs and one hip required bone grafting of a large acetabular osteolytic lesion with retention of the cup. A further 4 patients have significant osteolytic defects and 2 have minor osteolytic lesions. Wear measurements in the unrevised hips have shown a mean linear wear rate of 0.079mm/yr (range 0.000 to 0.222mm). 33% of these hips have a wear rate of > 0.1 mm/yr and 25% have a wear rate of < 0.05mm/yr. We have found excellent clinical results with the use of the Morscher cup in this relatively young and active cohort. A small group of patients, however, have shown higher wear rates or osteolysis, and we emphasise the importance of continuing radiological review

Introduction. When using press-fit stems in revision total knee arthroplasty (TKA), diaphyseal engagement optimizes stability. Attempts to maximize press fit may lead to periprosthetic fracture; however, the literature offers no guidance regarding the prevalence or management of this complication. The purpose of this study is to report the incidence, risk factors, and outcomes of these fractures. Methods. 634 Stemmed implants (307 femoral and 327 tibial) from 413 consecutive revision TKAs were reviewed. Immediate and 6 week post-operative radiographs were examined. Patient age, gender, stem length, diameter, and offset were evaluated as potential risk factors for fracture occurrence using a paired t-test for continuous and a chi-square analysis for categorical variables. Results. 15 Periprosthetic fractures (2.4%) were identified including two femoral (0.65%) and 13 tibial (4.0%). 10 Fractures were non-displaced, 3 had cortical displacement <2mm, and 2 were displaced >2mm. 1 Femur fracture was recognized and fixed intra-operatively with cables. 11 patients with non or minimally displaced fractures were allowed to bear weight as tolerated and 2 were protected for 2 weeks. 1 Displaced fracture was braced for 3 months, while the other was casted for concomitant extensor allograft reconstruction. All fractures showed radiographic evidence of healing and all patients were able to painlessly bear weight within 6 months. There was no evidence of implant migration at a mean of 15 months (range 3-47 months). 1 Patient developed recurrent infection at 10 months; no other complications were identified. With the sample size available for study, no significant differences in age (p=0.09), implant parameters (p=0.06-0.85) or gender (p=0.37) were detected between the fracture and non-fracture groups. Conclusions. Periprosthetic fractures occurred in approximately 2.4% of press-fit stems in revision TKA, more commonly in the tibia than femur. All fractures were managed non-operatively without complication or loss of prosthetic fixation

A good primary mechanical stability is a prerequisite for secondary cementless stem fixation by osseointegration. The construction, basic shapes and their development, as well as the nature of the surface in the CLS system are thus directed towards this goal.

The biomechanical concept of the CLS stem is characterised by the three-dimensional V-form, the strongly accentuated ribs in the proximal region and the all-round conical form of the distal part of the stem. The construction uses the adaptable trabeculum for the primary fixation. The features that characterise the CLS stem are found both in the classical version and the varus version.

The fixation of the stem in the proximal area should guarantee that transmission of force is retained within this area. The interposition of the cancellous structures reduces the danger of the bond between the bone and prosthesis becoming stiff. On introduction, the axial ribs exercise a cutting action and promote stability. In order to avoid tension peaks, the surfaces of the distal part of the stem are well rounded. The shape of the distal part of the stem is kept relatively slender, thus direct contact with the cortex is avoided. This means reduced incidence of pain for the patient, plus the new trabecular structures can form between the cortex and the implant, which eventually result in osseointegration.

To what extent and how quickly an implant becomes integrated is not just a question of primary stability. Important factors that have an influence also include the material and the surface structures of the prosthesis. It is generally the case that new bone grows preferentially on protruding parts such as prosthesis ribs or edges, and also on existing trabeculae, such as those altered by the surgery. The formation of new bone tissue in association with the CLS prosthesis was thoroughly investigated in many histological studies. The coarse-grained titanium alloy is, to a great extent, osteophilic. This is demonstrated by the fact that bone marrow or new bone can form directly on the surface of the CLS prosthesis.

The indications can be calculated on the basis of four key parameters: age, sex, the degree of osteoporosis, and the morphology of the femur. The morphological-cortical index (MCI) is used as an instrument to determine the shape of the femur. This provides a reliable method of classification of one of three basic morphological types: trumpet-shaped, cylindrical, and dysplastic.

The first 300 consecutive primary total hip arthroplasty (THA) procedures (299 patients), from Dec. 1983 to Apr. 1985, using a collarless, three-dimensional tapered, straight, titanium alloy stem with a grit-blasted surface, were evaluated clinically and radiographically in up to 16 years of follow-up. Radiographic evaluation assessed Engh’s implant-bone femoral fixation score, implant-bone demarcation, and periprosthesis osteolysis. The average duration of long-term radiographic follow- up was 12.6 years (10–16 years).

Patients were evaluated clinically by the HHS system. At last examination, five hips were lost to follow-up and 69 patients had died. The femoral revision rate was 7% (two aseptic loosening, five septic, 12 osteolysis). Femoral component survivorship was 95% at 10 years and 90% at 14 years. Femoral implant-bone fixation was stable, bone ingrowth in 97% stable, fibrous fixation in 1% and unstable, fibrous-fixation in 2% of the cases revised for acetabular mobilisation.

The grit-blasted, press-fit, collarless, tapered femoral component continued to perform well. While considering a “first-generation” cementless stem, CLS is still in use without virtually any design modifications.

We reviewed the results at nine to 13 years of 125 total hip replacements in 113 patients using the monoblock uncemented Morscher press-fit acetabular component. The mean age at the time of operation was 56.9 years (36 to 74). The mean clinical follow-up was 11 years (9.7 to 13.5) and the mean radiological follow-up was 9.4 years (7.7 to 13.1). Three hips were revised, one immediately for instability, one for excessive wear and one for deep infection.

No revisions were required for aseptic loosening. A total of eight hips (7.0%) had osteolytic lesions greater than 1 cm, in four around the acetabular component (3.5%). One required bone grafting behind a well-fixed implant. The mean wear rate was 0.11 mm/year (0.06 to 0.78) and was significantly higher in components with a steeper abduction angle.

Kaplan-Meier survival curves at 13 years showed survival of 96.8% (95% confidence interval 90.2 to 99.0) for revision for any cause and of 95.7% (95% confidence interval 88.6 to 98.4) for any acetabular re-operation.

Purpose: We report the 10 to 13 year results of the PFC knee system at our institution.

Method/Results: Between 1992 and 1995 97 PFC primary knee arthroplasties were performed consecutively in 82 patients. 32 patients have subsequently died (37 knees) and four (4 knees) are lost to follow-up. Clinical and radiological review of 46 patients (56 knees) was performed at a mean of 11.1 years post-operatively. Outcome was assessed using the Charnley modification of the Merle D’Aubigne score, with a median of 5 for pain and 4 for function. Radiological failure was defined as progressive radiolucency (1 case), lysis (1 case) or subsidence (1 case). Polyethylene wear was detectable in 10 cases, with > 50% in two. There was 100% survivorship with revision for aseptic loosening as an endpoint. There has been one revision for infection and one patella resurfacing, giving a 98% survivorship with no re-operation. In addition one periprosthetic fracture above a well fixed femoral component, required a supracondylar nail.

Conclusions: The PFC gives excellent outcome and survivorship at 13 years, regardless of the experience of the operating surgeon. This demonstrates that with careful training the PFC is a reliable knee replacement in the long-term for trainers and trainees alike.

Introduction: The use of screw fixation for cementless porous-coated acetabular components for primary total hip arthroplasty (THA) remains controversial. Aim of this study was to evaluate initial acetabular implant stability and late acetabular implant migration with screw fixation of the acetabular component in order to answer the question whether screws are necessary for the fixation of the acetabular component in cementless primary THA.

Methods: In a prospective study, 102 patients (107 hips) were available for follow up after primary THA using a cementless, porous-coated acetabular component. Patients were followed up at 6 and 12 weeks, 6 and 12 months and annually thereafter to an average of 2.6 ± 1.7 years. A total of 428 standardized radiographs were analyzed by the Einzel-Bild-Röntgen-Analyse (EBRA)-digital method. Additionally, the Harris Hip Score (HHS, 0–100) was assessed at the latest follow-up.

Results: 101 (94.4 %) implants did not show significant migration of more than 1 mm of the acetabular component. Six (5.6%) implants showed a migration of more than 1 mm: in 3 cases (2.8%), migration was progressive during follow-up and led to a revision surgery due to aseptic loosening. In 3 cases, migration came to a halt and cups were claimed stable. Individuals without cup migration had an average HHS of 78.4 ± 22.9, whereas patients who showed a cup migration of > 1 mm had 53.3 ± 24.2. Statistical analysis did not reveal preoperative patterns that would identify future migration.

Discussion: and Conclusion: Our findings show that the use of screw fixation for cementless porous-coated acetabular components for primary THA does not prevent cup migration.

25 First metatarso phalangeal joint replacements using the MOJE implant were prospectively assessed. There were 13 females and 10 males, with an average age of 60 years (range 45–71 years). The main indication for surgery was a symptomatic Hallux Rigidus.

The minimum follow up period was 2 years (range 24–38 months). The patients were assessed before and after surgery using the AOFAS (American Orthopaedic Foot and Ankle Society Hallux Score). The mean pre operative AOFAS score was 45.60 and this improved to 85.63 after surgery. There was a significant improvement in the sub scale for pain, from 4.58 pre operatively to 31.25 post operatively. A 9.5⁰ improvement in the range of motion was noted.

The authors conclude that their study demonstrates that the use of the MOJE implant for the treatment of Hallux Rigidus is a safe and useful option, although a more long term follow up is indicated.

We set out to demonstrate the 10-year survivorship of the PFC sigma TKA in a young patient group.

Demographic and clinical outcome data were collected prospectively at 6 months, 18 months, 3 years, 5 years and 8–10 years post surgery.

The data were analysed using Kaplan Meier survival statistics with end point being regarded as death or revision for any reason.

203 patients were found to be < 55 years at the time of surgery. Four patients required revision and four patients died. Another four patients moved away from the region and were excluded from the study.

A total of 224 knees in 199 patients (101 male and 98 females.) 168 patients had a diagnosis of Osteoarthritis and 28 with inflammatory arthritis. Average age 50.6 years range 28–55 years (median 51). Ten-year survivorship in terms of revision 98.2% at ten years 95% confidence interval.

Our results demonstrate that the PFC Sigma knee has an excellent survival rate in young patients over the first 10 years. TKR should not be withheld from patients on the basis of age.

We set out to demonstrate the 10-year survivorship of the PFC sigma TKA in a young patient group.

Demographic and clinical outcome data were collected prospectively at 6 months, 18 months, 3 years, 5 years and 8-10 years post surgery.

The data were analysed using Kaplan Meier survival statistics with end point being regarded as death or revision for any reason.

203 patients were found to be ≤55 years at the time of surgery. Four patients required revision and four patients died. Another four patients moved away from the region and were excluded from the study.

A total of 224 knees in 199 patients (101 male and 98 females.) 168 patients had a diagnosis of Osteoarthritis and 28 with inflammatory arthritis. Average age 50.6 years range 28-55 years (median 51).

Ten-year survivorship in terms of revision 98.2% at ten years 95% confidence interval.

Our results demonstrate that the PFC Sigma knee has an excellent survival rate in young patients over the first 10 years.

TKR should not be withheld from patients on the basis of age.

Introduction

There are a number of options available for surgical management of hallux rigidus. Ceramic implants of the first metatarsophalangeal joint (MTPJ) have been available for years; however there are no published long-term results existing.

The PFC Sigma Cobalt Chrome Sigma (PFCSCC) was introduced in 2006, an update of the PFC Sigma designed to reduce backside wear. To help identify any significant early failures following its introduction, we prospectively identified all recipients over a one-year period. The patient's clinical, demographic and radiographic data, American Knee Society scores (AKSS), Oxford Knee scores (OKS) and SF-12 scores was recorded pre-operatively and at one, three and five years. 233 patients underwent 249 primary knee arthroplasties with the PFCSCC. Seventeen patients (19 knees) died and 29 patients (30 knees) were also lost to follow up at the five year point. The mean age was 66.6 (34–80) with 47.6% of the cohort being male. The mean five year follow-up was 1836 days (1530–2307). Five knees (2.2%) were revised for infection and three were revised for pain. The 5–year cumulative survival rate was 96.6% for any failure and 98.6% for aseptic failure. AKSS 32.6 (0–86.6) preoperatively, 80.7 (29–95) 5 years P < 0.001. OKS was 39.0 (22–53) preoperatively, 23.5 (4.7–42.3) 5 years P < 0.001. These results demonstrate a good early survivorship when compared to the old design PFC Sigma, however further follow-up to ten years is required.

Since cementless stem fixation in hip arthroplasty is becoming more and more common, the overall incidence of intraoperative femoral fractures has risen considerably. Depending on primary or revision arthroplasty, literature reports fracture rates between a few percent up to one third of the cases.

In this study, methods commonly applied in the field of structural testing were customized for this specified interference fit situation. A cementless hip system (ABG II, Stryker) was used on animal bones and biomechanical bones.

Transient excitation in the form of regular hammer strokes and sinusoidal excitation using a shaker served as an input. The output of the system under test was measured on the greater trochanter using a piezoelectric accelerometer.

The signals were digitized with a high-speed data acquisition system and analyzed in real-time with spectrum analysis software.

Analysis included threshold detection in the time domain to determine the time delay between the input and output transducer. Spectrum analysis in the frequency domain included FFT analysis and frequency response function analysis to identify shifts of fundamental frequencies and harmonics to describe the vibrational changes with increasing stability.

A digital imaging system was set up to take pictures of the metal-bone site to measure inducible displacement with each hammer impact and correlate it with the vibrometry results. Furthermore a strain gauge circularly mounted around the proximal femur monitored accurately any hairline fracture.

This study shows that changes of the vibrational spectrum are directly related to implant fit. The range of interest is well in the sonic range, which apparently is the reason for many surgeons to listen and ‘feel’ carefully during advancing the broach or the final implant into the femur.

The study is trying to extract critical vibrational parameters correlated with stability and femoral integrity. Due to the different dimensions of the tested animal bones and lack of soft tissue damping, further experiments on cadavers need to be carried out.

Vibrational spectrum analysis could prove to be a useful tool to readily assess implant stability and femoral integrity. It seems to be most beneficial in revision surgery or minimally invasive hip replacement, where the risk of femoral fractures is increased or fissures could easily be missed.

The present clinico-radiographical study evaluated the long term performance of a Ti-Al-V alloy cementless modular press-fit cups (Fitek™) having, on the outer surface, an oriented multilayer titanium mesh (Sulmesh™) with 65% tridimensional porosity and 2 fins applied to the outer surface. Fins were initially designed for anti-rotatory purposes but showed to give an excellent initial mechanical stability. Thus, in the following years, we have designed 2 other cups having 8 fins and ceramic insert. In this paper we compare the design and the results obtained with these 3 cups.

We have reviewed the first 100 consecutive FITEK cups implanted in 92 patients with an average FU of 9,7 years (range 9-11 years). Results were evaluated with the Harris score. We had 86 Excellent, 10 Good, 2 Fair and 2 Poor. In this series we always used 28 mm heads.

Dysplastic patients showed inferior results compared to arthritics patients in different parameters, as pain, limp, ROM (p < 0.05), putting socks and shoes (p < 0.05).

Radiographically, our cups were implanted in a fairly horizontal position (36.5° an average).

At the last FU radiolucent lines were present in 14 % of the cases, never progressive.

In no case we found a change of position of the cup, and in this series no revision was necessary.

Between 2005 and 2008 we have implanted 140 consecutive Delta Fins cups with ceramic-on-ceramic articulation. The fins of this cup have a trapezoidal shape, with HA coating. The cup has an interference of 2 mm. The Delta ceramic insert allows the use of 32 or 36 mm heads.

Clinico-radiographical results were very good. One cup needed to be revised for aseptic loosening consecutive to a surgical error (undersizing)

The H.M.S. cup is made of Porous Titanium with 8 fins having a triangular section, in order to increase their penetration into cortical bone. The ceramic insert allows even larger ceramic insert (32, 36 and 40). Preliminary clinico-radiographical results were excellent, with complete initial mechanical stability and great ROM due to the large ceramic heads.

The presence of fins on the outer surface of cementless cups enhances primary stability and fixation and the use of large ceramic heads improves ROM and subjective patients satisfaction.

This study was conducted to assess the results in two subgroups:a) the effect of the PFC Sigma as compared to the PFC total knee replacement in lowering patella lateral release rates and b) the results of severe fixed flexion deformity correction with emphasis on some technical operative details.

Data is collected prospectively on all patients undergoing total knee replacements for an ongoing research programmer. As part of this project, we assessed the patella lateral release rate in 954 knees performed between April 1994 and January 2000.

Lateral release was reached in 55 out of 592 PFC knees compared with 25 out of 362 Sigma knees. The overall lateral release rate was 8.3%.

Using the Chi squared test, there is a statistically significant lower lateral release rate using the Sigma system and the study also demonstrated a low overall lateral release rate in our entire series. The biomechanics of the PFC Sigma system and some operative technical points will be discussed in the talk.

As regards the fixed flexion deformity group data was once again collected prospectively on the Knee Society Scoring form. The results are as follows:

Preoperative flexion deformity > 20 degrees = 53 knees, (Range 20 to 60 degrees),

Preoperative Mean Knee Score = 17.2,

Postoperative flexion deformity < 5 degrees=91%

Postoperative Mean Knee Score = 90.04.

These numbers and results are comparable to other large series and some technical operative details will be discussed in the talk.

Aims

It is important to analyze objectively the hammering sound in cup press-fit technique in total hip arthroplasty (THA) in order to better understand the change of the sound during impaction. We hypothesized that a specific characteristic would present in a hammering sound with successful fixation. We designed the study to quantitatively investigate the acoustic characteristics during cementless cup impaction in THA.

Aims

It is important to analyze objectively the hammering sound in cup press-fit technique in total hip arthroplasty (THA) in order to better understand the change of the sound during impaction. We hypothesized that a specific characteristic would present in a hammering sound with successful fixation. We designed the study to quantitatively investigate the acoustic characteristics during cementless cup impaction in THA.

Restoration a joint's articular surface following degenerative or traumatic pathology to the osteochondral unit pose a significant challenge. Recent advances have shown the utility of collagen-based scaffolds in the regeneration of osteochondral tissue. To provide these collagen scaffolds with the appropriate superstructure novel techniques in 3D printing have been investigated. This study investigates the use of polyɛ-caprolactone (PCL) collagen scaffolds in a porcine cadaveric model to establish the stability of the biomaterial once implanted. This study was performed in a porcine cadaveric knee model. 8mm defects were created in the medial femoral trochlea and repaired with a PCL collagen scaffold. Scaffolds were secured by one of three designs; Press Fit (PF), Press Fit with Rings (PFR), Press Fit with Fibrin Glue (PFFG). Mobilisation was simulated by mounting the pig legs on a continuous passive motion (CPM) machine for either 50 or 500 cycles. Biomechanical tensile testing was performed to examine the force required to displace the scaffold. 18 legs were used (6 PF, 6 PFR, 6 PFFG). Fixation remained intact in 17 of the cohort (94%). None of the PF or PFFG scaffolds displaced after CPM cycling. Mean peak forces required to displace the scaffold were highest in the PFFG group (3.173 Newtons, Standard deviation = 1.392N). The lowest peak forces were observed in the PFR group (0.871N, SD = 0.412N), while mean peak force observed in the PF group was 2.436N (SD = 0.768). There was a significant difference between PFFG and PFR (p = 0.005). There was no statistical significance in the relationship between the other groups. PCL reinforcement of collagen scaffolds provide an innovative solution for improving stiffness of the construct, allowing easier handling for the surgeon. Increasing the stiffness of the scaffold also allows press fit solutions for reliable fixation. Press fit PCL collagen scaffolds with and without fibrin glue provide dependable stability. Tensile testing provides an objective analysis of scaffold fixation. Further investigation of PCL collagen scaffolds in a live animal model to establish quality of osteochondral tissue regeneration are required