The number of cemented femoral stems implanted in the United States continues to slowly decrease over time. Approximately 10% of all femoral components implanted today are cemented, and the majority are in patients undergoing hip arthroplasty for femoral neck fractures. The European experience is quite different. In the UK, cemented femoral stems account for approximately 50% of all implants, while in the Swedish registry, cemented stems still account for the majority of implanted femoral components. Recent data demonstrating some limitations of uncemented fixation in the elderly for primary THA, may suggest that a cemented femoral component may be an attractive alternative in such a group.

Two general philosophies exist with regards to the cemented femoral stem: Taper slip and Composite Beam. There are flagship implants representing both philosophies and select designs have shown excellent results past 30 years. A good femoral component design and cementing technique, however, is crucial for long-term clinical success.

The author's personal preference is that of a “taper slip” design. The cemented Exeter stem has shown excellent results past 30 years with rare cases of loosening. The characteristic behavior of such a stem is to allow slight subsidence of the stem within the cement mantle through the process of cement creep. One or two millimeters of subsidence in the long-term have been observed with no detrimental clinical consequences. There have been ample results in the literature showing the excellent results at mid- and long-term in all patient groups.

The author's current indication for a cemented stem include the elderly with no clear and definitive cutoff for age, most likely in females, THA for femoral neck fracture, small femoral canals such as those patients with DDH, and occasionally in patients with history of previous hip infection.

Modern and impeccable cement technique is paramount for durable cemented fixation. It is important to remember that the goal is interdigitation of the cement with cancellous bone, so preparing the femur should not remove cancellous bone. Modern technique includes distal plugging of the femoral canal, pulsatile lavage, drying of the femoral canal with epinephrine or hydrogen peroxide, retrograde fill of the femoral canal with cement with appropriate suction and pressurization of the femoral cement into the canal prior to implantation of the femoral component.

The dreaded “cement implantation syndrome” leading to sudden death can be avoided by appropriate fluid resuscitation prior to implanting the femoral component. This is an extremely rare occurrence today with reported mortality for the Exeter stem of 1 in 10,000.

A cemented femoral component has been shown to be clinically successful at long term. Unfortunately, the art of cementing a femoral component has been lost and is rarely performed in the US. The number of cemented stems, unfortunately, may continue to go down as it is uncommonly taught in residency and fellowship, however, it might find a resurgence as the limits of uncemented fixation in the elderly are encountered. National joint registers support the use of cemented femoral components, and actually demonstrate higher survivorship at short term when compared to all other uncemented femoral components. A cemented femoral component should be in the hip surgeons armamentarium when treating patients undergoing primary and revision THA.

Chronic extensor mechanism insufficiency around TKA is a very challenging pathology to treat. An insufficient extensor mechanism negatively affects implant survival and patient outcomes. There are several risk factors for extensor mechanism disruption and the surgeon should be aware and avoid these problems in the perioperative period. In appropriately selected patients, reconstruction of the extensor mechanism is a valid option. Whole extensor mechanism and Achilles tendon allograft reconstruction of the deficient extensor mechanism have been proposed with good early published results. These reconstructions, however, are expensive and with time may stretch and lead to recurrence of an extensor lag. An alternative to allograft, is the use of Marlex mesh as popularised by Browne and Hanssen. This technique uses a knitted monofilament polypropylene mesh that is secured to the patient's native lateral tissue and covered by an appropriately dissected and distalised vastus medialis muscle. The technique can be used for both patellar and quadriceps tendon deficiencies and can be done with or without implant revision and is currently the treatment of choice at the presenter's institution. The surgeon should be aware of the complexity and limitations of these three reconstructive techniques.

Aim

Toxin-antitoxin (TA) systems are small genetics elements found in the majority of bacteria which encode a toxin causing bacterial growth arrest and an antitoxin counteracting the toxic effect. In Salmonella and E. coli, TA systems were shown to be involved in the formation of persisters. Persisters are a bacterial subpopulation with low growth rate and high tolerance to antibiotics. They could be responsible for antibiotic treatment failure in chronic infections and relapses, notably in bone and joint infections (BJI) caused by Staphylococcus aureus. Currently, two type II TA system families were described in S. aureus, mazEF and axe/txe, but their physiological roles are not well described. In this work, we studied the importance of mazEF in the intracellular survival of S. aureus inside osteoblasts, one of the mechanisms considered in the chronicity of S. aureus BJI.

There are three major diagnoses that have been associated with early hip degeneration and subsequent hip replacement in young patients: FAI, hip dysplasia and hip osteonecrosis. I will focus mainly on the first two. Both conditions, if diagnosed early in the symptomatic patient, can be surgically treated in order to try to prevent further hip degeneration. But, what is the natural history of these disorders?

Our recent paper published this year described the natural history of hip dysplasia in a group of patients with a contralateral THA. At an average of 20 years, 70% of hips that were diagnosed at Tönnis Grade 0, had progression in degenerative changes with 23% requiring a THA at 20 years. Once the hip degeneration progressed to Tönnis 1, then 60% of hips progressed and required a THA. This natural history study demonstrates that degeneration of a dysplastic hip will occur in over 2/3 of the hips despite the limitations of activity imposed by a contralateral THA.

In this same study, we were unable to detect a significant difference in progression between FAI hips and those categorised as normal. FAI damage has been commonly considered to be “motion-induced” and as such, the limitations imposed by the THA, might have limited the progression in hip damage. Needless to say, progression was seen in about half of the hips at 10 years, but very few required a THA at final follow-up. We have recently presented data on a group of young asymptomatic teenagers with FAI. At 5 years of follow-up, the group of patients with limited ROM in flexion and internal rotation, cam deformity and increased alpha angles, depicting a more severe form of disease, showed MRI evidence of progression in hip damage and worst clinical scores than a control group. This data supports our initial impressions that FAI may truly lead to irreversible hip damage.

Is surgery always the option? I indicate surgery when the patient is symptomatic and has a correctable structural problem that has failed non-operative management. The data suggests that few patients improve with physical therapy, but activity modification may be an option in patients with FAI as the hip damage is mainly activity related. This may not be the case with hip dysplasia. For hip dysplasia, my current recommendations are in the form of a periacetabular osteotomy (PAO) to correct the structural problem. The procedure leads to improvement in pain as it takes care of the 4 pain generators in the dysplastic hip: the labrum, cartilage, abductors, and resultant instability. The labrum and cartilage are off-loaded with the PAO, the instability is improved by providing containment and the abductor pain is improved by improving the hip mechanics by medializing the acetabulum. I perform a hip arthroscopy prior to the PAO in the majority to treat the labrum and to perform a head neck junction osteochondroplasty, if needed. Correction of the dysplasia to a more normal hip, will improve the outcome of these hips in the long-term.

For FAI, arthroscopy has become the best option for management and today is considered the gold standard. A careful review of the imaging is important prior to surgical decision making as patient selection and surgical correction is key. Poor outcomes have been seen in patients with advanced degenerative changes (joint space narrowing, femoral head damage) or in patients with incomplete correction of the deformity. Open surgical correction is an option in cases where deformity precludes an arthroscopic treatment alone.

The number of cemented femoral stems implanted in the United States continues to slowly decrease over time. Approximately 10% of all femoral components implanted today are cemented, and the majority are in patients undergoing hip arthroplasty for femoral neck fractures. The European experience is quite different, in the UK, cemented femoral stems account for approximately 50% of all implants, while in the Swedish registry, cemented stems still account for the majority of implanted femoral components. Recent data demonstrating some limitations of uncemented fixation in the elderly for primary THA, may suggest that a cemented femoral component may be an attractive alternative in such a group.

Two general philosophies exist with regards to the cemented femoral stem: Taper slip and Composite Beam. There are flagship implants representing both philosophies and select designs have shown excellent results past 30 years. A good femoral component design and cementing technique, however, is crucial for long-term clinical success. The authors' personal preference is that of a “taper slip” design. The cemented Exeter stem has shown excellent results past 30 years with rare cases of loosening. The characteristic behavior of such a stem is to allow slight subsidence of the stem within the cement mantle through the process of cement creep. One or two millimeters of subsidence in the long-term have been observed with no detrimental clinical consequences. There have been ample results in the literature showing the excellent results at mid- and long-term in all patient groups.

The authors' current indications for a cemented stem include the elderly with no clear and definitive cutoff for age, most likely in females, THA for femoral neck fracture, small femoral canals such as those patients with DDH, and occasionally in patients with history of previous hip infection. Modern and impeccable cement technique is paramount for durable cemented fixation. It is important to remember that the goal is interdigitation of the cement with cancellous bone, so preparing the femur should not remove cancellous bone. Modern technique includes distal plugging of the femoral canal, pulsatile lavage, drying of the femoral canal with epinephrine or hydrogen peroxide, retrograde fill of the femoral canal with cement with appropriate suction and pressurization of the femoral cement into the canal prior to implantation of the femoral component.

The dreaded “cement implantation syndrome” leading to sudden death can be avoided by appropriate fluid resuscitation prior to implanting the femoral component. This is a extremely rare occurrence today with reported mortality for the Exeter stem of 1 in 10,000.

A cemented femoral component has been shown to be clinically successful at long term. Unfortunately, the art of cementing a femoral component has been lost and is rarely performed in the US. The number of cemented stems unfortunately may continue to go down as it is uncommonly taught in residency and fellowship, however it might find a resurgence as the limits of uncemented fixation in the elderly are encountered. National joint registers support the use of cemented femoral components, and actually demonstrate higher survivorship at short term when compared to all other uncemented femoral components. A cemented femoral component should be in the hip surgeons' armamentarium when treating patients undergoing primary and revision THA.

The technique involves impaction of cancellous bone into a cavitary femur. If segmental defects are present, the defects can be closed with stainless steel mesh. The technique requires retrograde fill of the femoral cavity with cancellous chips of appropriate size to create a new endomedullary canal. By using a set of trial impactors that are slightly larger than the real implants the cancellous bone is impacted into the tube. Subsequent proximal impaction of bone is performed with square tip or half moon impactors. A key part of the technique is to impact the bone tightly into the tube especially around the calcar to provide optimal stability. Finally a polished tapered stem is cemented using almost liquid cement in order to achieve interdigitation of the implant to the cancellous bone.

The technique as described is rarely performed today in many centers around the world. In the US, the technique lost its interest because of the lengthy operative times, unacceptable rate of peri-operative and post-operative fractures and most importantly, owing to the success of tapered fluted modular stems. In centers such as Exeter where the technique was popularised, it is rarely performed today as well, as the primary cemented stems used there, rarely require revision.

There is ample experience from around the globe, however, with the technique. Much has been learned about the best size and choice of cancellous graft, force of impaction, surface finish of the cemented stem, importance of stem length, and the limitations and complications of the technique. There are also good histology data that demonstrate successful vascularization and incorporation of the impacted cancellous bone chips and host bone.

Our experience at the clinic was excellent with the technique as reported in CORR in 2003 by M Cabanela. The results at mid-term demonstrated minimal subsidence and good graft incorporation. Six of 54 hips, however, had a post-operative distal femoral fracture requiring ORIF. The use of longer cemented stems may decrease the risk of distal fracture and was subsequently reported by the author after reviewing a case series from Exeter.

Today, I perform this technique once or twice per year. It is an option in the younger patient, where bone restoration is desired. Usually in a Paprosky Type IV femur, where a closed tube can be recreated and the proximal bone is reasonable. If the proximal bone is of poor quality, then I prefer to perform a transfemoral osteotomy, and perform an allograft prosthetic composite instead of impaction grafting, and wrap the proximal bone around the structural allograft. I prefer this technique as I can maintain the soft tissues over the bone and avoid the stripping that would be required to reinforce the bone with struts or mesh. Another indication for its use in the primary setting is in the patient with fibrous dysplasia.

90% of young patients that develop DJD of the hip have an underlying structural problem, most frequently hip dysplasia. The structural problem results in decreased contact area, increased contact stresses about the anterior and lateral acetabulum and femoral head and results in labral pathology, early cartilage damage and if left untreated leads to end stage hip arthritis.

Despite the optimism of alternative bearing surfaces and highly cross linked polyethylene, THA should still be discouraged in young patients. Many patients with symptomatic hip dysplasia in the absence of arthritis will benefit from joint preservation. The goal of treatment should be restoration of anatomy as close to normal as possible. The Bernese PAO is the preferred technique in many centres in North America and Europe because of its balance between minimal exposure, complications, and ability to provide optimal correction. The ideal patient for a PAO is young, has no arthritis, is not obese (BMI <30) and has poorly covered femoral head where congruency is possible. A PAO has advantages over other osteotomies and include: 1)

Performed through one incision without violation of the abductors

The results of the osteotomy have been encouraging with up to 60% survivorship free from total hip arthroplasty at 20 years. Most studies show improvement in pain and function, improvement in radiographic coverage of the femoral head with no improvement in range of motion. Treatment should be individualised to each patient based on radiographic findings, age and cartilage status and restoration of anatomy as close to normal as possible should be the ideal treatment, most commonly in the form of a periacetabular osteotomy.

The majority of patients who develop hip arthritis have a mechanical abnormality of the joint. The structural abnormalities range from instability (DDH) to impingement. Impingement leads to osteoarthritis by chronic damage to the acetabular labrum and adjacent cartilage.

In situations of endstage secondary DJD, hip arthroplasty is the most reliable treatment choice. In young patients with viable articular cartilage, joint salvage is indicated. Treatment should be directed at resolving the structural abnormalities that create the impingement.

Femoral abnormalities corrected by osteotomy or increased head-neck offset by chondro-osteoplasty creating a satisfactory head-neck offset. This can safely be done via anterior surgical dislocation or arthroscopically. The acetabular-labral lesions can be debrided and/or repaired. Acetabular abnormalities should be corrected by “reverse” PAO in those with acetabular retroversion or anterior acetabular debridement in those with satisfactory posterior coverage and a damaged anterior rim.

Often combinations of the above are indicated.

ORIF is the treatment of choice for the majority of acetabular fractures with the ultimate goal of native hip preservation. As long as anatomic reduction and joint congruency is achieved, the results of ORIF have led to good to excellent outcomes. Total hip arthroplasty (THA) after acetabular fracture is indicated: 1.) acutely in the setting of a fracture where ORIF has been shown to portray a poor prognosis (severe femoral head and/or posterior wall impaction, dome comminution (gull sign) or 2.) in the presence of the sequelae of acetabular fractures such as posttraumatic arthritis or osteonecrosis. Independent of the setting, THA after acetabular fracture presents unique challenges to the orthopaedic surgeon and in many instances requires a team approach that includes both joint reconstruction and trauma specialists. The main goal of the operation is to restore continuity of the fractured columns prior to implantation of an uncemented acetabular component. Technical challenges include infection, residual pelvic deformity, acetabular bone loss and/ or ununited fractures, osteonecrosis of bone fragments, retained hardware, heterotopic ossification, sciatic nerve compromise, and the difficulties in obtaining long-term socket fixation. Careful pre-operative assessment with review of x-rays and CT scans to assess bone loss, fracture nonunion, and infection is necessary. The surgeon must anticipate more blood loss, longer operative times, and difficulties with exposure and must anticipate the need of special tools intra-operatively such as pelvic reconstruction plates, use of autogenous bone graft, metal cutting instruments and post-operative heterotopic ossification prophylaxis either in the form of NSAIDS or radiation. In case of a necrosis, nonunion, or bone loss principles of revision total hip arthroplasty are commonly used and today the use of highly porous metals is particularly useful. Cemented acetabular components should be avoided. Care should be taken with cup position as distorted anatomy may influence cup position and bony impingement may lead to dislocation. The results of THA in general has provided excellent pain relief and functional improvement but the biggest historical problem has been socket fixation and bearing surface wear, hopefully now improved with the advent of highly porous metals and alternative bearing surfaces.

Purpose

We describe an update of our experience with the implantation of the first 325 Exeter Universal hips. The fate of every implant is known.