Introduction

Total hip replacements using highly cross-linked polyethylene show excellent clinical outcomes, low wear, and minimal lysis at 5 years follow-up. A recent RSA study reports a significant increase in femoral head penetration between 5 and 7 years. This study is a multi-center radiographic analysis to determine whether the RSA observation is present in a large patient cohort.

Sir John Charnley unquestionably was the pioneer of modern joint arthroplasty. He was also an innovator in many other areas of orthopedics, including fracture care and arthrodesis, but this tribute will focus on his contributions to arthroplasty.

Charnley pioneered the use of methyl methacrylate cement and in so doing provided the first reliable means of fixing implants to bone. For the first time, this provided arthritis patients with reproducible long-term, reliable pain relief from advanced joint arthritis. Charnley also pioneered the use of a novel bearing surface, high molecular weight polyethylene. In so doing, he pioneered resurfacing of both sides of a joint with a low-friction, low-wear bearing. This provided the potential for excellent pain relief and also durable function of a hip arthroplasty.

Charnley understood the importance of reproducing joint mechanics and kinematics, and the arthroplasties he designed fully reproduced leg length and hip offset, and therefore the mechanics of the hip.

Finally, Charnley understood that technology is only a great value when it can be transferred effectively to many surgeons around the world. He created a carefully constructed educational structure to teaching the methodology in a way that would allow surgeons to practice this procedure successfully in other centers. Charnley understood the importance of minimizing complications for a procedure to be widely adopted and successful.

It is no exaggeration to state that Charnley’s contributions have helped tens of millions of patients worldwide who otherwise would have been permanently crippled by arthritis. Today’s further advances in joint arthroplasty are all dependent on the foundations of joint arthroplasty pioneered by Sir John Charnley.

Purpose of the study: Few data are available concerning the proper management of patients with a periprosthetic fracture of the hip who presents biological signs of inflammation (increased WBC, sedimentation rate, or C-reactive protein). The purpose of this work was to determine the prevalence of elevated biological markers in this type of patient and to determine the reliability of such markers for the diagnosis of periprosthetic infection.

Material and methods: A periprosthetic hip fracture was diagnosed in 204 patients from 2000 to 2006. The WBC count, the sedimentation rate and the serum CRP level were noted at admission to the emergency ward. The diagnosis of infection was confirmed by at least two positive bacteriological samples of tissue biopsy and/or joint fluid collected at surgery. A statistical analysis was conducted to determine the prevalence of elevated biological markers of inflammation, the sensitivity, their specificity and their positive predictive value for deep infection.

Results: Twenty-one patients (11.6%) developed a periprosthetic infection. Among the 204 patients, the WBC count increased in 16.2%, sedimentation rate in 33.3% and CRP in 50.5%. The sensitivity was 24% (WBC), 50% (sedimentation rate) and 83% (CRP). The specificity was 85% (WBC), 69% (sedimentation rate) and 56% (CRP). The positive predictive value was low (18, 21 and 29% respectively).

Discussion: Markers of inflammation are frequently ordered before surgery to search for infection but can be elevated for various reasons. Most often, these markers are elevated because of the patient’s general status and are thus related to other co-morbid conditions and/or reaction to the new fracture. In this population, the WBC count did not contribute to the diagnosis of infection as only 24% of the infected patients had a high count. CRP and sedimentation rate and the WBC count had low positive predictive values.

Conclusion: This study shows that an isolated elevation of biological markers of inflammation in a patient with a periprosthetic fracture is not a good indicator of infection.

Introduction: The International Knee Documentation Committee (IKDC) recommends use of the IKDC score to document subjective, objective and functional ACL outcome. To further improve knowledge concerning patient QOL after ACL reconstruction, an additional specific QOL questionnaire was developed. Using a combination of univariate and multivariate analysis the patient factors and surgical factors that influenced QOL 5- years after ACL reconstruction were determined.

Materials: 500 patients operated on for arthroscopic ACL reconstruction at our institution between 1997 and 2001 were prospectively enrolled. Patient psychosocial profile, sport expectations, knee exam, type of graft, associated lesion, type of anesthesia, complications, IKDC, KT 2000 at 6 moths, 1 year and 2 years were recorded. At five years, patients were asked to complete a 5-subscale validated QOL questionnaire for ACL deficiency. A multivariate analysis was performed to identify the factors influencing 5-year QOL.

Results: 203 patients completed the 5-years QOL questionnaire. Responders did not statistically differ from non responders. Patient subjective factors such as: patient expectations, pre-operative symptoms, work-school concerns, recreations concerns, social and psycho-social concerns were significantly (p< 0.05) and independently associated with the five-year QOL results. Objective factors such as meniscus tears and results of the KT 2000 (p< 0.05) were the two surgical factors correlated with 5-year QOL.

Discussion: In this large prospective study, most of the factors influencing the 5-year QOL results after ACL reconstruction were related to patient expectations, psycho-social, symptoms and work-sport concerns. The presence of a meniscus tear and greater KT 2000 laxity also contributed to poorer 5-year QOL results.

Studies of patients having primary THR using highly cross-linked polyethylene show excellent clinical outcomes and very low radiographic wear results at a minimum of 5 years follow-up. Recently, a radiostereometric analysis (RSA) study of a small group of patients reported that after no detectable wear during years 1–5, they found a significant increase in femoral head penetration between 5 and 7 years follow-up. However, this increase in head penetration after 5 years has not been confirmed in a larger patient cohort.

The purpose of this study was to organize a multicenter radiographic study involving leading medical centers in the U.S. having the longest-term follow-up available on this type of highly cross-linked polyethylene in order to determine if the RSA observation can be confirmed in a larger study.

Six academic centers agreed to contribute radiographic data to this study. All patients received primary total hip replacements with Longevity polyethylene liners (Zimmer, Warsaw, IN) coupled with 26, 28, and 32mm cobalt chrome femoral heads. The radiographic inclusion criteria required a minimum of four radiographs per patient: one at 1 year; at least one from 2 to 4.5 years; one 4.5 to 5.5 years; and at least one from 5.5 to 9 years follow-up. The Martell Hip Analysis Suit-eTM software was used for the wear analysis. All wear values were determined by calculating head penetration between the follow-up radiograph and the 1-year radiograph to remove creep, the majority of which has been shown to occur during the first year. Separate linear regressions, representing the wear rates, were computed for the early period from 1 year to 5.5 years and the late period from 5.5 years to 9 years follow-up. The Zar test was used to determine the significance of the difference between these two linear regressions.

We present the completed analysis of 165 hips. When the early and late data points were combined into one data set, the second-order regression indicated an inflection point at 6.3 years with a slightly positive inflection. There were 402 film comparisons in the early time period, and the slope and confidence interval of the regression line was 4.9μm/yr (95% CI of −28μm/yr to 38μm/yr). There were 188 film comparisons in the late period, and slope of the regression line for the late period was 10.8 μm/yr (95% CI of −58μm/yr to 80μm/yr). The Zar test showed no significant difference between the two slopes (Figure 1, p=0.886).

No significant increase in femoral head penetration was found for the late period after 5 years compared to the early period before 5 years follow-up in either analysis. Additionally, no significant late increase in wear was seen within individuals. While we continue to enroll patients, at this time we do not observe the increase in wear seen in the RSA study after 5 years.

Introduction and Aims: Hip arthroplasty alters stress patterns in the proximal femur, thereby influencing femoral bone remodelling. The purpose of our study was to determine long-term skeletal response to wellfixed total hip arthroplasty.

Method: Seventy-two hips in 66 patients (mean age 57, range 25–72; 29 male, 37 female) were evaluated with standardised measurement protocol after arthroplasty with cemented Charnley (32 hips) or uncemented 5/8 coated AML stem (40 hips). Inclusion criteria: stable implants and complete radiographic record with minimum follow-up 15–20 years. 3159 measurements were made with power calipers and normalised for magnification.

Results: There was time dependent loss of proximal cortical thickness around both stems (AML greater than Charnley; proximal medial greater than proximal lateral cortex, (p< 0.05, all parameters). At 15–20 years, median proximal medial cortical thickness decreased by 12% for Charnley and 70% for AML stems. Median proximal lateral cortical thickness decreased by 9% for Charnley and 21% for AML stems. Median cortical thickness changes around the mid and distal prosthesis for both stems was mild, with a non-statistically significant trend (p> 0.05) towards more cortical loss (2–9%) around Charnley than AML stems (0–8%). The median intramedullary width increased by 1–10%, depending on level (no difference by prosthesis type, p> 0.05). Changes continued progressively over the entire observation period.

Conclusion: This paper provides the first detailed long-term information on the effect of well-functioning hip arthroplasty on femoral morphology in a large patient group. Morphologic changes are most pronounced in the proximal medial femur and vary by implant type. Also, the medullary canal widens around a replaced hip as the patient ages.

The fixation concept of a fluted, conical, tapered grit-blasted titanium stem has been employed successfully in Europe, but the experience in North America with implants of this design is more limited. The most commonly studied stem of this design, the Wagner stem has been reported to provide good pain relief function and implant stability in several aeries, although large series with long-term follow-up are lacking.

Implants with a similar distal geometry but modular proximal features were introduced in an attempt to solve one of the practical difficulties of using a stem of this design: determining where the implant would seat was difficult, trialing options were limited, and accurate leg length and soft tissue balancing were difficult. Modular implants are more user-friendly but have the theoretical disadvantage of introducing the potential for modular junction failure (failure due to fatigue or fretting). To date, there are only limited (but favourable) short-term reported results on the efficacy of this form of revision.

Implants of this design can be used when rotational stability, axial stability, and long-term implant fixation must be gained primarily from the distal diaphysis of the femur. Examples include patients with periprosthetic femur fractures and patients with marked proximal bone thinning but good diaphyseal bone.

From the practical viewpoint, the fluted section of these implants must be straight (to allow milling of a cone-shaped diaphysis) and thus anterior cortical perforation is a potential complication. Anterior extended osteotomy as described by Wagner accomplishes the goal of femoral exposure and helps prevent distal anterior femoral perforation.

Uncemented hemispherical sockets are the implant of choice for most acetabular revisions. Several studies at mid-term document good clinical results, and furthermore, the implants are both versatile and technically straightforward to insert. When bone loss is present, the indications for uncemented sockets are expanded by using jumbo uncemented cups or uncemented cups placed at a high hip center. The main limitation of uncemented hemispherical cups is the need to place them on sufficient host bone to provide initial mechanical stability with a high, long-term likelihood of biologic fixation. The amount of host bone needed to meet these criteria has been debated. One rule of thumb that has been used is 50% surface area contact of the shell with host bone. However, for large sockets with a large surface area, a smaller percentage of the surface in contact with host bone may prove acceptable, provided the shell has host bone support in key areas including a peripheral rim fit and support in the dome of the socket.

When these criteria cannot be fulfilled, an alternative method of acetabular reconstruction must be considered. These alternatives include structural bone grafts, impaction grafting, and anti-protrusio cages. Anti-protrusio cages have the advantage of distributing forces over a large surface area of native bone, resisting migration, and being compatible with either bulk or particulate graft in massive acetabular deficiencies. These implants do not provide for biologic fixation and thus their use probably is best restricted to situations in which porous coated implants are not likely to work.

Pelvic discontinuity is a specific form of acetabular bone deficiency in which there is a transverse fracture of the acetabulum. Usually this occurs in association with marked acetabular bone loss and represents a stress fracture through deficient bone. Preoperative findings suggestive of pelvic discontinuity include: medial/lateral offset of the superior pelvis relative to the inferior hemipelvis, malrotation of the inferior hemipelvis relative to superior hemipelvis, or visible fracture line demonstrating the pelvic discontinuity. Judet films and true lateral radiographs of the hip can be helpful to delineate the presence of pelvic discontinuity.

The treatment principles for pelvic discontinuity include the following: 1.) gain stable fixation of the new acetabular implant. When the bone deficiency is relatively modest this may be possible with a hemispherical uncemented socket. Frequently, however, bone deficiency is massive and an anti-protrusio cage is necessary; 2.) restore pelvic continuity and stability. Usually this is possible with just a posterior column plate; 3.) bone graft large defects using particulate versus structural bone graft. In massive deficiencies structural bone grafts have the advantage of bridging the discontinuity and allowing healing of the native pelvis to the structural graft inferiorly and superiorly which may promote healing of the discontinuity.

The results of treatment of pelvic discontinuity are dependent on the severity of bone loss and whether or not the pelvis had previous therapeutic radiation; milder bone loss is associated with better results; and more severe bone loss and previous therapeutic pelvic radiation with worse results.

Surgery for pelvic discontinuity is complex and the most common complications include recurrent instability, infection, and sciatic neuropathy.

Prevention: Many periprosthetic femur fractures may be prevented by: (1) good patient follow-up, (2) timely reoperation of lytic lesions if radiographs suggest fracture risk, and (3) prophylactic use of longer stemmed implants or strut grafts to bypass cortical defects at revision surgery.

Treatment: Periprosthetic fractures can be treated using an algorithmic approach based on the Vancouver classification system. Fractures of greater or lesser trochanter (Type A)

Nonoperative treatment if displacement acceptable and if not associated with lysis

These fractures almost always require surgery. Nonoperative treatment is associated with high rate of malunion, nonunion, poor results. Treatment is according to fixation status of implant and bone quality.

Well-fixed stem (Type B1): ORIF with cable plate and/or strut grafts

* Principles: obtain fracture stability, implant stability, and optimise conditions for bone healing (use bone grafts, don’t strip periosteum)

Loose stem, unreconstructable proximal bone damage (Type B3): revise substituting for proximal femur with allograft prosthetic composite or tumour prosthesis

Ten cases are described of catastrophic failure of the polyethylene liner of three different designs of uncemented acetabular component. Failure occurred as a result of either 'wearthrough' to the metal backing, liner fracture or a combination of both, at a mean of 4.6 years after implantation (2 to 7.6). At revision there was metallosis in all hips and osteolysis of the femur or the pelvis in six. Catastrophic failure was seen only in cups with a minimum polyethylene thickness of less than 5 mm.

Revision hip arthroplasty in patients with massive acetabular bone deficiency has generally given poor long-term results. We report the use of an 'anti-protrusio cage', secured to the ischium and ilium, which bridges areas of acetabular bone loss, provides support for the acetabular socket, and allows pelvic bone grafting in an environment protected from excessive stress. Forty-two failed hip arthroplasties with massive acetabular bone loss were revised with the Burch-Schneider anti-protrusio cage and evaluated after two to 11 years (mean five years). There was failure due to sepsis in five hips (12%) and aseptic loosening in five (12%); the remaining 32 hips (76%) showed no evidence of acetabular component failure or loosening.