Large Femoral Head Research Articles

Acetabular Alignment and Primary Arc of Motion for Minus, Skirtless, and Skirted 28-, 32-, 36-, and 40-mm Femoral Heads

We examined the influence of acetabular cup alignment on the primary arc of motion (PAOM) for minus (−3.5), skirtless (+3.5), and skirted (+10.5) neck lengths with 28-, 32-, 36-, and 40-mm femoral heads. Total hip arthroplasty was performed in a pelvic saw bone model. The acetabulum was positioned in 30°/45°/60° abduction and 0°/15°/30° anteversion, respectively. The PAOM was determined using a digital inclinometer for each of the acetabular positions and 12 femoral heads mentioned above. Best PAOM was found in 45° abduction and 15° to 30° anteversion as well as 60° abduction and 0° anteversion. Combinations of excessive abduction and anteversion as well as horizontalization and retroversion resulted in the worst PAOM. Primary arc of motion is mainly determined by cup alignment even when using larger femoral heads.

Large Femoral Heads Decrease the Incidence of Dislocation After Total Hip Arthroplasty

The use of larger femoral heads has been proposed to reduce the risk of dislocation after total hip arthroplasty, but there is a lack of evidence to support this proposal. The aim of this multicenter randomized controlled trial was to determine whether the incidence of dislocation one year after total hip arthroplasty is significantly lower in association with the use of a 36-mm femoral head articulation as compared with a 28-mm articulation. Six hundred and forty-four middle-aged and elderly patients undergoing primary or revision arthroplasty were randomized intraoperatively to receive either a 36 or 28-mm metal femoral head on highly cross-linked polyethylene. Patients who were at high risk of dislocation (including those with dementia and neuromuscular disease) and those undergoing revision for the treatment of recurrent hip dislocation or infection were excluded. Patients were stratified according to other potential risk factors for dislocation, including diagnosis and age. Diagnosis of hip dislocation required confirmation by a physician and radiographic evidence of a dislocation. Overall, at one year of follow-up, hips with a 36-mm femoral head articulation had a significantly lower incidence of dislocation than did those with a 28-mm articulation (1.3% [four of 299] compared with 5.4% [seventeen of 316]; difference, 4.1% [95% confidence interval, 1.2% to 7.2%]) when controlling for the type of procedure (primary or revision) (p = 0.012). The incidence of dislocation following primary arthroplasty was also significantly lower for hips with a 36-mm femoral head articulation than for those with a 28-mm articulation (0.8% [two of 258] compared with 4.4% [twelve of 275]; difference, 3.6% [95% confidence interval, 0.9% to 6.8%]) (p = 0.024). The incidence of dislocation following revision arthroplasty was 4.9% (two of forty-one) for hips with a 36-mm articulation and 12.2% (five of forty-one) for hips with a 28-mm articulation; this difference was not significant with the relatively small sample size of the revision group (difference, 7.3% [95% confidence interval, -5.9% to 21.1%]) (p = 0.273). Compared with a 28-mm femoral head articulation, a larger 36-mm articulation resulted in a significantly decreased incidence of dislocation in the first year following primary total hip arthroplasty. However, before a 36-mm metal-on-highly cross-linked polyethylene articulation is widely recommended, the incidence of late dislocation, wear, periprosthetic osteolysis, and liner fracture should be established.

Low Early and Late Dislocation Rates with 36- and 40-mm Heads in Patients at High Risk for Dislocation

Large (36- and 40-mm) femoral heads with highly crosslinked polyethylene liners were introduced to reduce the risk of dislocation after primary total hip arthroplasty (THA), but it is unclear whether the risk is reduced and whether there is osteolysis or liner fracture. We therefore determined (1) the incidence of early and late (>5years) dislocation; (2) the rate of femoral and acetabular component loosening and revision; and (3) the rate of liner fracture and pelvic osteolysis. We retrospectively reviewed 112 patients presumed at high risk for dislocation who had 122 primary THAs: 108 with 36-mm and 14 with 40-mm femoral heads. The risk factors were: age>75years (80 hips); proximal femur fracture (18); history of contralateral dislocation (two); history of alcohol abuse (two); large acetabulum>60mm (six); and other (14). Patients were evaluated for early (<1year) and late (>5years) dislocation; rate of reoperation; clinical result with Harris hip score; and standard radiographic analysis for radiolucent lines and osteolysis. The rate of early dislocation was 4% (five of 122 hips), all with a 36-mm head. There were no late dislocations in 74 hips followed for 5 to 10years, no revision for acetabular or femoral loosening, and no liner fractured. There were no hips with pelvic osteolysis and seven hips with an acetabular radiolucent line. The 36- and 40-mm femoral heads were associated with a low risk of dislocation in high-risk patients undergoing primary THA with no osteolysis or liner fracture. Level IV, therapeutic study. See the Guidelines for Authors for a complete description of level of evidence.

Hip resurfacing in patients under thirty years old: an attractive option for young and active patients

Metal-on-metal hip resurfacing is offered as an alternative to traditional hip arthroplasty for young, active adults with advanced osteoarthritis. The concept of hip resurfacing is considered very attractive for this specific population (hard-on-hard bearing component with a large femoral head limiting the risk of dislocation, and allowing femoral bone stock preservation). A prospective clinical trial was designed to investigate the outcome of hip resurfacing in young patients (under 30 years old). We studied 24 hips in 22 patients. Mean age at operation was 24.9 years (range 17.1-29.9). No patient was lost to follow-up. There was no revision at average follow-up of 50.6 months (44-59). Mean UCLA activity score improved from 5.5 (1-9) pre-operatively to 7.6 (1-10) postoperatively (p < 0.001). Mean Harris hip score increased from 43.9 (19-67) to 89.3 (55-100) (p < 0.001). Radiological analysis discerned no osteolysis and no implant migration. The absence of short-term complications, such as mechanical failure or dislocation, is encouraging and leads us to think that mid-term results will be satisfactory. Moreover, the specific advantages of hip resurfacing (bone stock preservation, excellent stability, low risk of dislocation, large-diameter head) make the procedure a very attractive option for young subjects.

The role of large femoral head components in revision of total hip arthroplasty

To study the efficiency of decreasing instability of large femoral head components in revision total hip arthroplasty (THA). From August 2005 to December 2010, 107 patients (112 hips) with 28 mm femoral head components (28 mm group) and 46 patients (46 hips) with 36 mm femoral head components (36 mm group) in revision THA were analyzed retrospectively in order to find if the dislocation rate and Harris hip score were different between the two groups at the time of last follow-up. All the operations were performed by the first author. There were 81 male patients (85 hips) and 26 female patients (27 hips) in 28 mm group with mean age of (62±17) years (26-79 years) and 33 male patients (33 hips) and 13 female patients (13 hips) in 36 mm group with mean age of (60±16) years (31-77 years). The mean follow-up period was 43.3 months (33-71 months) for 28 mm group and 26.7 months (12-37 months) for 36 mm group. There were 7 patients dislocated after revision in 28 mm group, including 2 revised with reinforcement rings (with dislocation rate 9.5%), 3 revised with impaction bone grafting technique (with dislocation rate 8.3%) and 2 revised with cementless cups (with a dislocation rate 3.6%). The dislocation rate of this group was 6.2%. While the dislocation rate of 36 mm group was 2.2%, the only dislocated patient was because of loss of gluteus medius muscle function in the index operation. If this case was excluded, the dislocation rate of 36 mm group would be 0. There was significant difference between the two groups (χ2=103.0095, P<0.01). The Harris hip score was 88±11 for 28 mm group and 89±9 for 36 mm group, there was no significant difference between the two groups (P>0.05). The large femoral head components can significantly decrease the instability after revision THA, which should be used in revision THA.

Effect of Restoration of Combined Offset on Stability of Large Head Tha

Improvements in bearing technology have resulted in a reduction in wear and larger femoral heads to reduce dislocation rates. We retrospectively reviewed 668 primary THAs (580 patients) inserted with 32 mm or 36 mm femoral heads (1/2003-6/2007) performed through a posterior approach with posterior repair. Patients received a questionnaire assessing instability and dislocations. We compared clinical and radiographic data between patients with and without dislocations. Follow-up averaged 3.4 years (range 2-6.6 years). The dislocation rate was 1.3% (9/668). Decreasing the combined postoperative offset (lateral offset + medial offset measurements) and using acetabular cups larger than 58 mm in outer diameter increased the risk of dislocation. A majority of the hips that dislocated had negative combined offset and abduction angles in the upper and lower quartiles of all hips studied. Appropriate positioning should be used to minimise dislocation risk in THAs inserted with large femoral heads.

Socket position determines hip resurfacing 10-year survivorship.

Modern metal-on-metal hip resurfacing arthroplasty designs have been used for over a decade. Risk factors for short-term failure include small component size, large femoral head defects, low body mass index, older age, high level of sporting activity, and component design, and it is established there is a surgeon learning curve. Owing to failures with early surgical techniques, we developed a second-generation technique to address those failures. However, it is unclear whether the techniques affected the long-term risk factors. We (1) determined survivorship for hips implanted with the second-generation cementing technique; (2) identified the risk factors for failure in these patients; and (3) determined the effect of the dominant risk factors on the observed modes of failure. We retrospectively reviewed the first 200 hips (178 patients) implanted using our second-generation surgical technique, which consisted of improvements in cleaning and drying the femoral head before and during cement application. There were 129 men and 49 women. Component orientation and contact patch to rim distance were measured. We recorded the following modes of failure: femoral neck fracture, femoral component loosening, acetabular component loosening, wear, dislocation, and sepsis. The minimum followup was 25 months (mean, 106.5 months; range, 25-138 months). Twelve hips were revised. Kaplan-Meier survivorship was 98.0% at 5 years and 94.3% at 10 years. The only variable associated with revision was acetabular component position. Contact patch to rim distance was lower in hips that dislocated, were revised for wear, or were revised for acetabular loosening. The dominant modes of failure were related to component wear or acetabular component loosening. Acetabular component orientation, a factor within the surgeon's control, determines the long-term success of our current hip resurfacing techniques. Current techniques have changed the modes of failure from aseptic femoral failure to wear or loosening of the acetabular component. Level III, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

Early Results of Large Head Metal-on-Metal Hip Arthroplasties

Total hip arthroplasty significantly improves patient's life quality. However, total joint replacement is associated with possible complications, such as dislocations, infections, fractures and periprosthetic osteolysis. The goal of this study was to evaluate a large head metal-on-metal total hip arthroplasties and analyse short term complications related to them. Between 9/2005 and 6/2009, a total of 691 hip replacements were performed on 635 patients with the use of Magnum M2 large head cementless metal-on-metal prosthesis in Turku University Hospital. All patients had a scheduled follow-up at two to three months, and at one year. The results were evaluated using X-rays, Harris Hip Score (HHS), and evaluating post-operative complications and reasons for re-operations. During our follow-up the HHS median raised from its preoperative value of 59.8 to 86.4 two to three months after the operation, and to 93.9 one year after the operation. As a complication we had five infections requiring single open debridement (early infection) or a two stage revision. Seven patients had a periprosthetic femoral fracture that was operated and 11 patients were reoperated because of acetabular component malposition, fracture or early loosening. We did not observe any dislocations, n. ischiadicus damages, squeeking or complications related to high metal ion release (ALVAL-reactions (Aseptic Lymphocyte-dominated Vasculitis-Associated Lesion) or pseudotumours). The metal-on-metal bearing pair allows large femoral head size, which decreases the risk for dislocation. It may also decrease the risk for osteolysis and aseptic loosening in a long run. Early complication rate related to the bearing surface is minimal. Metal-on-metal prosthesis is a good choice for young and active patients with good bone quality.

Free Vascularized Fibula Graft to Treat Chondroblastoma of the Hip

Chondroblastomas are rare tumors that present in the epiphysis of the long bones. Bone grafting following aggressive surgical curettage has yielded the best results. When present in the femoral head, they pose a higher risk of recurrence due to the difficulty of achieving an adequate resection without destroying the structural integrity of the weight-bearing surface. This article describes a case of surgical treatment of a chondroblastoma of the femoral head with the use of a free vascularized fibula graft. A 26-year-old woman had several months of increasing left hip pain and decreased range of motion. Imaging studies confirmed a large bubbly lesion with sclerotic borders in the left femoral head consistent with chondroblastoma. After performing an aggressive and complete excisional biopsy, a large cavitary defect remained in the femoral head. Reconstruction of the defect and structural support was achieved using a free vascularized fibula. Nine years postoperatively, the patient had full hip motion, no pain, and no radiographic evidence of collapse. A free vascularized fibula graft is an excellent option for the reconstruction of a large femoral head defect after chondroblastoma resection.

Dual-mobility bearings: a review of the literature

Dislocation after total hip arthroplasty remains a major problem and hip instability is the most common reason for revision. These complications are costly to both patients and the healthcare system, and efforts to reduce them have had varied degrees of success. Although there are well documented patient and surgical risk factors for dislocation, the typical surgical solutions offered (constrained liners, large femoral heads) have the drawbacks of reduced range-of-motion and high rates of revision. Dual-mobility prostheses (unconstrained tripolar prostheses) are hip design solutions to dislocation that aim to provide a greater stability with an increased range-of-motion, along with potentially reduced wear. The mean overall dislocation rate from multiple combined studies using dual-mobility prostheses was 0.1% for primary total hip arthroplasty and 3.5% for revisions, compared with 2–7% for standard primary total hip arthroplasties and up to 16% for revisions. Dual-mobility prostheses offer a viable option for treating recurrent dislocation as well as for primary and revision arthroplasty.

A Case of a C-Stem Fracture at the Head-Neck Junction and a Review of the Literature

We report the first case of a fracture of the standard C-stem in combination with a large metal-on-metal articulation. This occurred at the head-neck junction. Analysis of the fractured stem showed evidence of fatigue failure with possible corrosion. The use of large femoral heads with neck adaptors and narrow tapers should be used with caution, especially in heavy, active patients.

A Multinational Assessment of Metal-on-Metal Bearings in Hip Replacement

There is emerging evidence that many metal-on-metal (MoM) bearings, when used with large femoral heads in conventional hip replacement and some resurfacing prostheses, are associated with increased rates of revision arthroplasty. Registries are the main sources of data on MoM prostheses. At the recent International Consortium of Orthopaedic Registries (ICOR) meeting, data were presented from the Australian, England and Wales, and New Zealand registries. All registries reported an increased rate of revision for large femoral head MoM prostheses when prostheses were aggregated compared with the aggregated data of hip prostheses with other bearing surfaces. There was also evidence, however, that the outcome varied, depending on the type of prostheses used, in both large femoral head MoM conventional hip replacement as well as resurfacing hip replacement.The relevance of the recent isolated case reports on systemic metal toxicity was also discussed at the ICOR meeting. Although systemic metal toxicity appears to be a rare occurrence, there is a need to undertake appropriately designed studies to define the true prevalence of this phenomenon. There may be advantages in nesting these studies within registries. The ICOR meeting highlighted the implications of the MoM experience for the orthopaedic industry, regulators, and surgeons.

Ultrasound Screening of Periarticular Soft Tissue Abnormality Around Metal-on-Metal Bearings

Although metal hypersensitivity or pseudotumors are concerns for metal-on-metal (MoM) bearings, detailed pathologies of patterns, severity, and incidence of periprosthetic soft tissue lesions are incompletely understood. We examined the potential of ultrasound for screening of periarticular soft tissue lesions around MoM bearings. Ultrasound examinations were conducted in 88 hips (79 patients) with MoM hip resurfacings or MoM total hip arthroplasties with a large femoral head. Four qualitative ultrasound patterns were shown, including normal pattern in 69 hips, joint-expansion pattern in 11 hips, cystic pattern in 5 hips, and mass pattern in 3 hips. Hips with the latter 3 abnormal patterns showed significantly higher frequency of clinical symptoms, without significant differences of sex, duration of implantation, head sizes, and cup abduction/anteversion angles, compared with hips with normal pattern. Ultrasound examination provides sensitive screening of soft tissue reactions around MoM bearings and may be useful in monitoring progression and defining treatment for periarticular soft tissue abnormalities.

The Frank Stinchfield Award: Dislocation in Revision THA: Do Large Heads (36 and 40 mm) Result in Reduced Dislocation Rates in a Randomized Clinical Trial?

Dislocation after revision THA is a common complication. Large heads have the potential to decrease dislocation rate, but it is unclear whether they do so in revision THA. We therefore determined whether a large femoral head (36 and 40 mm) resulted in a decreased dislocation rate compared to a standard head (32 mm). We randomized 184 patients undergoing revision THA to receive either a 32-mm head (92 patients) or 36- and 40-mm head (92 patients) and stratified patients by surgeon. The two groups had similar baseline demographics. The primary end point was dislocation. Quality-of-life (QOL) measures were WOMAC and SF-36. The mean followup for dislocation was 5 years (range, 2-7 years); the mean followup for QOL was 2.2 years (range, 1.6-4 years). In the 36- and 40-mm head group, the dislocation rate was 1.1% (one of 92) versus 8.7% (eight of 92) for the 32-mm head. There was no difference in QOL outcomes between the two groups. Our observations confirm a large femoral head (36 or 40 mm) reduces dislocation rates in patients undergoing revision THA at short-term followup. We now routinely use large heads with a highly crosslinked polyethylene acetabular liner in all revision THAs. Level I, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Robotic Guidance in Total Hip Arthroplasty: The Shape of Things to Come

Surgeons want to perform a perfect total hip arthroplasty (THA) with every operation. Human performance has limitations, especially when performing a mechanical operation in a biological environment. Recent suggested changes to improve outcomes have been large femoral heads and anterior incisions, but unfortunately, neither has resulted in any scientific data that change has been effected. The scientific data tell us that poor component positions and impingement are the source of increasing mechanical complications. Therefore, attempts have been made to improve the surgeon's performance by precise quantitative knowledge in the operating room. Robotic-guided navigation provides numerical data for cup inclination plus anteversion and center of rotation; femoral leg length and offset; and combined anteversion of the cup and stem. The acetabular bone preparation is done with a reamer connected to a robotic arm, which prevents human error by the surgeon of reaming off line or too deep. This technology provides predictable and reproducible results.

Metal-on-Metal Total Hip Arthroplasty: High Failure Rates with Large Femoral Heads

Metal-on-Metal Total Hip Arthroplasty: High Failure Rates with Large Femoral Heads

Dislocation Rate after Hip Arthroplasty within the First Postoperative Year: 36Mm versus 28Mm Femoral Heads

Dislocation is a common and important complication of total hip arthroplasty (THA). Larger femoral heads may reduce the risk of dislocation and improve the range of movement. The aim of this study was to compare the relative risk (RR) of dislocation during the first year after THA between implants with 28 mm and 36 mm femoral heads. 198 consecutive hips with 28 mm femoral head (Group-28) and 259 hips with 36 mm femoral head (Group-36) were studied. The patients were assessed preoperatively and periodically using the Harris hip score (HHS) and radiographic analysis. The relative risk (RR) of dislocation was calculated. The average HHS significantly improved from a preoperative baseline to the last follow-up at 82.1 months (28 mm) and 44.3 months (36 mm). No statistically significant differences were revealed between the two groups for HHS results and complications (p>0.05), but the difference in RR of dislocation within the first year between the two groups was 7.85 (95% CI: 1.34-46.03), p=0.046.Although dislocation is multifactorial in etiology, the two groups were homogenous for all principal contributing factors except the diameter of the femoral head. Therefore, the use of 36-mm heads can reduce the risk of dislocation following THA by a factor of 8 compared to conventional 28 mm heads.

Robotic assisted total hip arthroplasty using the MAKO platform

Surgeons want to perform a perfect total hip replacement (THR) with every operation. Human performance has limitations, especially when performing a mechanical operation in a biological environment. Recent suggested changes to improve outcomes have been large femoral heads and anterior incisions, but unfortunately neither has resulted in any scientific data that change has been effected. The scientific data does tell us that poor component positions and impingement are the source of increasing mechanical complications. Therefore, attempts to improve the surgeon's performance by precise quantitative knowledge in the operating room have been used. We discuss robotic guided navigation as a solution. This technology provides predictable and reproducible results.

Lower rates of dislocation with increased femoral head size after primary total hip replacement

Increased femoral head size may reduce dislocation rates following total hip replacement. The National Joint Registry for England and Wales has highlighted a statistically significant increase in the use of femoral heads ≥ 36 mm in diameter from 5% in 2005 to 26% in 2009, together with an increase in the use of the posterior approach. The aim of this study was to determine whether rates of dislocation have fallen over the same period. National data for England for 247 546 procedures were analysed in order to determine trends in the rate of dislocation at three, six, 12 and 18 months after operation during this time. The 18-month revision rates were also examined. Between 2005 and 2009 there were significant decreases in cumulative dislocations at three months (1.12% to 0.86%), six months (1.25% to 0.96%) and 12 months (1.42% to 1.11%) (all p < 0.001), and at 18 months (1.56% to 1.31%) for the period 2005 to 2008 (p < 0.001). The 18-month revision rates did not significantly change during the study period (1.26% to 1.39%, odds ratio 1.10 (95% confidence interval 0.98 to 1.24), p = 0.118). There was no evidence of changes in the coding of dislocations during this time. These data have revealed a significant reduction in dislocations associated with the use of large femoral head sizes, with no change in the 18-month revision rate.

Open Repair and Arthroscopic Follow-Up of Severely Delaminated Femoral Head Cartilage Associated with Traumatic Obturator Fracture-Dislocation of the Hip

This article describes an unusual case of a young adult with traumatic obturator fracture-dislocation of the hip, involving a large femoral head fragment and severe delamination of articular cartilage. The dislocation was irreducible by closed reduction because of interposing soft tissues, including the rectus femoris and iliopsoas muscles, and torn joint capsules, and therefore, open reduction was performed using an anterolateral approach in the lateral decubitus position. The large femoral head fragment was released from the ligamentum teres and fixed to the dislocated femoral head with headless screws. The severely delaminated femoral head cartilage was repaired with suture anchors and absorbable sutures. The patient was kept nonweight bearing for 6 weeks postoperatively, and was then allowed to resume full weight bearing gradually. He returned to normal activities of daily living at 14 weeks. At 9 months postoperatively, arthroscopic examination showed complete healing of the fracture and cartilage lesions, and at 12-month follow-up, there was no clinical or radiographic evidence of arthritis or osteonecrosis. The patient had no pain or limp, and achieved an excellent result according to Epstein's clinical evaluation criteria. To our knowledge, no previous report exists on the arthroscopic follow-up of a repaired femoral head cartilage in patients with obturator fracture-dislocation of the hip along with a large femoral head fragment and severe delamination of articular cartilage.