Ligament reconstruction following multi-ligamentous knee injuries involves graft fixation in bone tunnels using interference screws (IS) or cortical suspensory systems. Risks of IS fixation include graft laceration, cortical fractures, prominent hardware, and inability to adjust tensioning once secured. Closed loop suspensory (CLS) fixation offers an alternative with fewer graft failures and improved graft-to-tunnel incorporation. However, graft tensioning cannot be modified to accommodate errors in tunnel length evaluation. Adjustable loop suspensory (ALS) devices (i.e., Smith & Nephew Ultrabutton) address these concerns and also offer the ability to sequentially tighten each graft, as needed. However, ALS devices may lead to increased graft displacement compared to CLS devices. Therefore, this study aims to report outcomes in a large clinical cohort of patients using both IS and CLS fixation. A retrospective review of radiographic, clinical, and patient-reported outcomes following ligament reconstruction from a Level 1 trauma centre was completed. Eligible patients were identified via electronic medical records using ICD-10 codes. Inclusion criteria were patients 18 years or older undergoing ACL, PCL, MCL, and/or LCL reconstruction between January 2018 and 2020 using IS and/or CLS fixation, with a minimum of six-month post-operative follow-up. Exclusion criteria were follow-up less than six months, incomplete radiographic imaging, and age less than 18 years. Knee dislocations (KD) were classified using the Schenck Classification. The primary outcome measure was implant removal rate. Secondary outcomes were revision surgery rate, deep infection rate, radiographic fixation failure rate, radiographic malposition, Lysholm and Tegner scores, clinical graft failure, and radiographic graft failure. Radiographic malposition was defined as implants over 5 mm off bone or intraosseous deployment of the suspensory fixation device. Clinical graft failure was defined as a grade II or greater Lachman, posterior drawer, varus opening at 20° of knee flexion, and/or valgus opening at 20° of knee flexion. Radiographic failure was defined when over 5 mm, 3.2 mm, and/or 2.7 mm of side-to-side difference occurred using PCL gravity stress views, valgus stress views, and/or varus stress views, respectively. Descriptive statistics were used. Sixty-three consecutive patients (mean age = 41 years, range = 19-58) were included. A total of 266 CLS fixation with Ultrabuttons and 135 IS were used. Mean follow-up duration was 383 days. Most injuries were KD type II and III. Graft revision surgery rate was 1.5%. Intraosseous deployment occurred in 6.2% and 17% had implants secured in soft tissue, rather than on bone. However, the implant removal rate was only 6.2%. Radiographic PCL gravity stress views demonstrated an average of 1.2 mm of side-to-side difference with 6.2% meeting criteria for radiographic failure. A single patient met radiographic failure criteria for collateral grafts. Mean Lysholm and Tegner scores were 87.3 and 4.4, respectively, with follow-up beyond one year. Both IS and CLS fixation demonstrate an extremely low revision surgery rate, a high rate of implant retention, excellent radiographic stability, and satisfactory patient-reported outcome scores. Incorrect implant deployment was seen in a total of 17% of patients, yet none required implant removal. A single patient required graft revision due to implant failure

The purpose of this study is to evaluate risk factors for distal construct failure (DCF) in posterior spinal instrumented fusion (PSIF) in adolescent idiopathic scoliosis (AIS). We observed an increased rate of DCF when the pedicle screw in the lowest instrumented vertebra (LIV) was not parallel to the superior endplate of the LIV, however this has not been well studied in the literature. We hypothesise a more inferiorly angled LIV screw predisposes to failure and aim to find the critical angle that predisposes to failure. A retrospective cohort study was performed on all patients who underwent PSIF for AIS at the Starship Hospital spine unit from 2010 to 2020. On a lateral radiograph, the angle between the superior endplate of the LIV was measured against its pedicle screw trajectory. Data on demographics, Cobb angle, Lenke classification, instrumentation density, rod protrusion from the most inferior screw, implants and reasons for revision were collected. Of 256 patients, 10.9% (28) required at least one revision. The rate of DCF was 4.6% of all cases (12 of 260) and 25.7% of revisions were due to DCF. The mean trajectory angle of DCF patients compared to all others was 13.3° (95%CI 9.2° to 17.4°) vs 7.6° (7° to 8.2°), p=0.0002. The critical angle established is 11°, p=0.0076. Lenke 5 and C curves, lower preoperative Cobb angle, titanium only rod constructs and one surgeon had higher failure rates than their counterparts. 9.6% of rods protruding less than 3mm from its distal screw disengaged. We conclude excessive inferior trajectory of the LIV screw increases the rate of DCF and a screw trajectory greater than 11° predisposes to failure. This is one factor that can be controlled by the surgeon intraoperatively and by avoiding malposition of the LIV screw, a quarter of revisions can potentially be eliminated

Introduction. Total knee replacement (TKR) is an established and effective surgical procedure in case of advanced osteoarthritis. However, the rate of satisfied patients amounts only to about 75 %. One common cause for unsatisfied patients is the anterior knee pain, which is partially caused by an increase in patellofemoral contact force and abnormal patellar kinematics. Since the malpositioning of the tibial and the femoral component affects the interplay in the patellofemoral joint and therefore contributes to anterior knee pain, we conducted a computational study on a cruciate-retaining (CR) TKR and analysed the effect of isolated femoral and tibial component malalignments on patellofemoral dynamics during a squat motion. Methods. To analyse different implant configurations, a musculoskeletal multibody model was implemented in the software Simpack V9.7 (Simpack AG, Gilching, Germany) from the SimTK data set (Fregly et al.). The musculoskeletal model comprised relevant ligaments with nonlinear force-strain relation according to Wismans and Hill-type muscles spanning the lower extremity. The experimental data were obtained from one male subject, who received an instrumented CR TKR. Muscle forces were calculated using a variant of the computed muscle control algorithm. To enable roll-glide kinematics, both tibio- and patellofemoral joint compartments were modelled with six degrees of freedom by implementing a polygon-contact-model representing the detailed implant surfaces. Tibiofemoral contact forces were predicted and validated using data from experimental squat trials (SimTK). The validated simulation model has been used as reference configuration corresponding to the optimal surgical technique. In the following, implant configurations, i.e. numerous combinations of relative femoral and tibial component alignment were analysed: malposition of the femoral/tibial component in mediolateral (±3 mm) and anterior-posterior (±3 mm) direction. Results. Mediolateral translation/malposition of the tibial component did not show high influence on the maximal patellofemoral contact force. Regarding the mediolateral translation of the femoral component, similar tendencies were observed. However, lateralisation of the femoral component (3 mm) clearly increased the lateral patella shift and medialisation of the tibial component (3 mm) led to a slightly increased lateral patella shift. Compared to the reference model, pronounced posterior translation of the tibial and femoral component resulted in a lower patellofemoral contact force, further increasing with higher anterior translation of the components. The translation of the tibial component showed smaller influence on the patellofemoral contact force than the translation of the femoral component. Discussion. In our present study, the mediolateral malposition of the femoral and tibial component showed no major impact on patellofemoral contact force and contribution to anterior knee pain in patients with CR TKR. However, the influence of implant component positioning in anterior-posterior direction on patellofemoral contact force is evident, especially for the femoral component. Our generated musculoskeletal model can contribute to computer-assisted preclinical testing of TKR and may support clinical decision-making in preoperative planning

Recurrent dislocation following total hip arthroplasty (THA) is a complex, multifactorial problem that has been shown to be the most common indication for revision THA. At our center, we have tried to approach the unstable hip by identifying the primary cause of instability and correcting that at the time of revision surgery. Type 1:. Malposition of the acetabular component treated with revision of the acetabular component and upsizing the femoral head. Type 2:. Malposition of the femoral component treated with revision of the femur and upsizing the femoral head. Type 3:. Abductor deficiency treated with a constrained liner or dual mobility bearing. Type 4:. Soft tissue or bony impingement treated with removal of impingement sources and upsizing the femoral head. Type 5:. Late wear of the bearing treated with bearing surface exchange and upsizing the femoral head. Type 6:. Unclear etiology treated with a constrained liner or dual mobility articulation. These may be patients with abnormal spino-pelvic motion. The most common etiologies of instability in our experience include cup malposition (Type 1) and abductor deficiency (Type 3). We reviewed 75 hips revised for instability and at a mean 35.3 months 11 re-dislocations occurred (14.6%). Acetabular revisions were protective against re-dislocation (p<0.02). The number of previous operations (p=0.04) and previously failed constrained liners (p<0.02) were risk factors for failure. The highest risk of failure was in patients with abductor insufficiency with revisions for other etiologies having a success rate of 90%. Although instability can be multifactorial, by identifying the primary cause of instability, a rational approach to treatment can be formulated. In general the poorest results were seen in patients with abductor deficiency. Given the high rate of failure of constrained liners (9 of the 11 failures were constrained), we currently are exploring alternatives such as dual mobility articulations. Our early experience with dual mobility suggests improved results when compared to constrained liners

Recurrent dislocation following total hip arthroplasty (THA) is a complex, multifactorial problem that has been shown to be the most common indication for revision THA. At our center, we have tried to approach the unstable hip by identifying the primary cause of instability and correcting that at the time of revision surgery. Type 1: Malposition of the acetabular component treated with revision of the acetabular component and upsizing the femoral head. Type 2: Malposition of the femoral component treated with revision of the femur and upsizing the femoral head. Type 3: Abductor deficiency treated with a constrained liner or dual mobility bearing. Type 4: Soft tissue or bony impingement treated with removal of impingement sources and upsizing the femoral head. Type 5: Late wear of the bearing treated with bearing surface exchange and upsizing the femoral head. Type 6: Unclear etiology treated with a constrained liner or dual mobility articulation. The most common etiologies of instability in our experience include cup malposition (Type 1) and abductor deficiency (Type 3). We reviewed 75 hips revised for instability and at a mean 35.3 months, 11 re-dislocations occurred (14.6%). Acetabular revisions were protective against re-dislocation (p<0.02). The number of previous operations (p=0.04) and previously failed constrained liners (p<0.02) were risk factors for failure. The highest risk of failure was in patients with abductor insufficiency with revisions for other etiologies having a success rate of 90%. Although instability can be multifactorial, by identifying the primary cause of instability, a rational approach to treatment can be formulated. In general, the poorest results were seen in patients with abductor deficiency. Given the high rate of failure of constrained liners (9 of the 11 failures were constrained), we currently are exploring alternatives such as dual mobility articulations. Our early experience with dual mobility suggests improved results when compared to constrained liners

Recurrent dislocation following total hip arthroplasty (THA) is a complex, multifactorial problem that has been shown to be the most common indication for revision THA. At our center, we have tried to approach the unstable hip by identifying the primary cause of instability and correcting that at the time of revision surgery. Type 1: Malposition of the acetabular component treated with revision of the acetabular component and upsizing the femoral head. Type 2: Malposition of the femoral component treated with revision of the femur and upsizing the femoral head. Type 3: Abductor deficiency treated with a constrained liner or dual mobility bearing. Type 4: Soft tissue or bony impingement treated with removal of impingement sources and upsizing the femoral head. Type 5: Late wear of the bearing treated with bearing surface exchange and upsizing the femoral head. Type 6: Unclear etiology treated with a constrained liner or dual mobility articulation. The most common etiologies of instability in our experience include cup malposition (Type 1) and abductor deficiency (Type 3). We reviewed 75 hips revised for instability and at a mean 35.3 months 11 re-dislocations occurred (14.6%). Acetabular revisions were protective against re-dislocation (p<0.015). The number of previous operations (p=0.0379) and previously failed constrained liners (p<0.02) were risk factors for failure. The highest risk of failure was in patients with abductor insufficiency with revisions for other etiologies having a success rate of 90%. Although instability can be multifactorial, by identifying the primary cause of instability, a rational approach to treatment can be formulated. In general the poorest results were seen in patients with abductor deficiency. Given the high rate of failure of constrained liners (9 of the 11 failures were constrained), we currently are exploring alternatives such as dual mobility articulations

Management of recurrent instability of the hip requires careful assessment to determine any identifiable causative factors. While plain radiographs can give a general impression, CT is the best methodology for objective measurement. Variables that can be measured include: prosthetic femoral anteversion, comparison to contralateral native femoral anteversion, total offset from the medial wall of the pelvis to the lateral side of the greater trochanter, comparison to total offset on the contralateral side, acetabular inclination, & acetabular anteversion. Wera et al describe potential causes of instability. These are typed into I. Acetabular Component Malposition; II. Femoral Component Malposition; III. Abductor Deficiency; IV. Impingement; V. Late Wear; and VI. Unknown. Acetabular component malposition is the most common cause of instability and so measurement of cup orientation is essential. It is well known that excessive or inadequate anteversion can lead to anterior and posterior dislocation respectively but horizontal components are also associated with posterior dislocation due to deficient posterior/inferior acetabular surface. Similarly, excessive or inadequate femoral anteversion can be easily identified on CT as can insufficient total offset of the reconstructed joint compared to the contralateral side. This can be caused by medialization of the acetabular component. Abductor deficiency can be a soft-tissue cause of instability, but it certainly isn't the only one. Knowledge of the prior surgical exposure can be instructive. Anterior exposures can be prone to deficient anterior capsule just as posterior exposures can be prone to deficient posterior capsule and short rotators, while anterolateral and lateral exposures can be associated with gluteus minimus and gluteus medius compromise. Impingement, whether involving implants, bone, or soft tissue are primarily secondary to the above factors, if osteophytes were properly trimmed at the index procedure. Correction of the incorrect variables is the primary goal of revision for instability and greatly preferable to using salvage options such as dual-mobility or constrained articulations which invoke additional concerns. Ultimately though, such salvage options are necessary if the cause of the instability cannot be determined or can be determined but not corrected. Bracing, while highly inconvenient and sometimes impractical for certain patients, still has a role in specific circumstances. Formal analysis of the unstable prosthetic reconstruction is the key to successful treatment

Spezializing in subfields of Orthopaedics is common in anglo-american countries for more than 20 years. IThe aim of this paper is to demonstrate the necessity of fellowship programms in extremity orientated subfileds of orthopaedics. Analyzing the results of ankle arthrodesis performed by general orthopaedic surgeons campared to ankle arthrodesis performed by spezialized foot and ankle surgeons the difference in results will be demonstrated. Patients and methods. In 40 patients an ankle arthrodesis was performed between 1998 and 2012. Group A was formed by 20 consecutive patients treated by spezial trained Foot and Ankle surgeons and group B was formed by 20 patients treted by general orthopaedic surgeons. The average age in group A at the time of surgery was 59,9y (34 to79y) compared to 63,4y (41 to 80y) in group B. The average follow up was 34 months respectively 32 months after surgery. The study included a spezial questionnaire with the AOFAS score and rating of patients dissatisfaction. The successful healing of the arthrodesis was determied by using standardized radiographs, Furthermore a pedobarography, and a videoanalyzis of the walking was incuded. Results. All procedures in group A were performed using an anterior approach. Neither pseudarthroses, equinus or other malositions were detected in this group. In group B wurdenin 16 patients an anterior and in 4 patients a lateral approach was used. Complications included 3 pseudarthroses, 4 equinus malpositions, 4 varus malpositions, 4 valgus malpositions and 8 penetrations of the subtalar joint. The AOFAS score on average was 78 (46–92) points in group A and 75 (34 – 94) in group B. Conclusion. The analyzis of the data revealed that the results in Group A were comparable to the results published in the literature. Results in group B were inferior to those in group A and to the results published in the literature of Foot and Ankle surgery. Foot and Ankle surgery became more demanding over the last decades. As already shown in anglo-american countries spezializing in certain fields of orthopaedics is a necessity. More complex hindfoot surgery should be performed in special centers with an adequate case load

Introduction. Recurrent dislocation following total hip arthroplasty (THA) is a complex, multifactorial problem that has been shown to be the most common indication for revision THA. The purpose of this study was to classify causes of instability and evaluate outcomes based on an algorithmic approach to treatment. Methods. Two surgeons performed 77 consecutive revisions for instability. Patients had a mean of 2 (range, 0 to 6) prior operative attempts to resolve their instability. Subjects were divided into 6 types based on the etiology of instability: I) malposition of the acetabular component, II) malposition of the femoral component, III) abductor deficiency, IV) impingement, V) late wear, or VI) unclear etiology. Types I /II were treated with revision of the malpositioned component, Type III/VI with a constrained liner, Type IV by removing sources of impingement and Type V with a liner change. Large (>36 mm) femoral heads were used routinely. Results. The causes of instability were Type I: 25 (33%); Type II: 8 (10%); Type III: 28 (37%); Type IV: 7 (9%); Type V: 5 (7%); Type VI: 3 (4%). At a mean of 32.5 months (Range, 24 to 79) 12 patients re-dislocated (15.6%). Among these 12 failures 8 (75%) were in patients with abductor insufficiency (Type III) treated with a constrained liner. Conclusions. The most common causes of instability were cup malposition and abductor insufficiency. Our treatment protocol had an 84.4% success rate. The highest risk of failure was in patients with abductor insufficiency with a revision for other etiologies having a success rate of 92%

There has recently been an increase in the number of hip replacement procedures performed through an anterior approach. Every procedure has a risk profile, and in the case of a new procedure or technique it is important to investigate the incidence of complications. The aim of this study is to identify the complications encountered in the first 100 patients treated with the minimally invasive anterior approach. This is a case series of the first 100 hips treated and were assessed for complications. These were classified according to the severity and outcome [1]. The 100 hip comprised of 98 patients; 46 males and 52 females with an average operation age on 70.1 (±9.38) years. There were 2 bilateral procedures. Specific patient selection criteria were used. All complications occurred within one month of surgery. Complications such as fracture, deep vein thrombosis (DVT), cup malposition, femoral stem malposition, retained screw, excessive acetabular reaming and skin numbness were noted. Complications associated with fracture were characterized as either periprosthetic or trochanteric. Clinical outcome scores of SF36v2, WOMAC, Harris Hip and Tegner activity score were analysed at pre-operative, 6 months, 12 months 24 months and 36 months intervals. A total of 13 early complications occurred. Of these 13 complications the most common complications were trochanteric fracture, 3 instances (3.00%), periprosthetic fracture, 2 (2.00%), DVT, 2 (2.00%), numbness, 2 (2.00%) and loosening. Other complications recorded were cup malposition, 1 (1.00%), femoral stem malpositon, 1 (1.00%), retained screw, 1 (1.00%) and excessive acetabular reaming, 1 (1.00%). All fractures occurred in patients over the age of 60 years. Significant differences (p<0.05) were observed between all clinical outcomes measures pre-operatively and postoperatively (6, 12, 24 and 36 months). The unfamiliarity of the approach, however, increased operating time, and exposure problems, lead to trochanteric fracture

Background:. Varus-valgus constrained (VVC) implants are used in cases of severe valgus deformity, attenuated medial collateral ligament and difficulty in balancing the medial and lateral gaps of the knee. The increased constraint has been postulated to lead to more stress at the bone-implant interface and early loosening. The objective of this study was to compare the wear characteristics of the polyethylene liner in VVC prosthesis with the posterior-stabilized (PS) prosthesis and identify the factors leading to more wear in the VVC tibial inserts. Methods:. This was a retrieval analysis of all VVC liners collected from patients who underwent revision surgery from 1999 to 2011. These patients were matched to another group with posterior-stabilized inserts who underwent revision in the same time period. These two groups of patients were similar in terms of their demographic data and implant dimensions. Inserts were divided into 16 zones and a microscopic analysis of surface damage was carried out. We determined overall damage with a scoring system. Pre-revisions radiographs were reviewed and analyzed for correlation with the wear profile. Results:. There was significantly more damage in the posts of the VVC group (13.0 ± 5.0, compared to 4.7 ± 1.9 in the PS group) (p < 0.001). There was no difference in the backside wear, or wear in the medial and lateral compartments. Within the VVC group, the total damage score and cold flow damage were significantly higher with excessive joint line changes (≥ 5 mm). The excessive joint line elevation was associated with rotational wear pattern of the post (p = 0.004). The total abrasion and pitting scores were also higher in knees without proper restoration of the limb alignment (> 3° varus or valgus). Femoral component malposition correlated with higher total cold flow, pitting, debris damage scores, wear in medial and lateral compartments, and the anterior portion of the insert. The total damage scores for the posts in the VVC group were significantly higher with anterior tibial slope, and tibial component malposition. The most common cold flow deformation was found in the posterior post, followed by the anterior post. The cold flow damage to the post was significantly higher in excessive joint line changes (anterior and posterior post) and in tibial malposition (medial and lateral post). Conclusion:. The increased constraint resulted in more post damage. Joint line elevation, femoral and tibial component malposition, and anterior tibial slope resulted in significantly more wear in the VVC inserts

Introduction:. Recurrent dislocation following total hip arthroplasty (THA) is a complex, multifactorial problem that has been shown to be the most common indication for revision THA. The purpose of this study was to classify causes of instability and evaluate outcomes based on an algorithmic approach to treatment. Methods:. Two surgeons performed 77 consecutive revisions for instability. Patients had a mean of 2 years (range, 0 to 6) prior operative attempts to resolve their instability. Subjects were divided into 6 types based on the etiology of instability: I) malposition of the acetabular component, II) malposition of the femoral component, III) abductor deficiency, IV) impingement, V) late wear, or VI) unclear etiology. Types I /II were treated with revision of the malpositioned component, Type III/VI with a constrained liner, Type IV by removing sources of impingement and Type V with a liner change. Large (>36mm) femoral heads were used routinely. Results:. The causes of instability were Type I: 25 (33%); Type II: 8 (10%); Type III: 28 (37%); Type IV: 7 (9%); Type V: 5 (7%); Type VI: 3 (4%). At a mean of 32.5 months (Range, 24 to 79) 12 patients re-dislocated (15.6%). Among these 12 failures 8 (75%) were in patients with abductor insufficiency (Type III) treated with a constrained liner. Conclusions:. The most common causes of instability were cup malposition and abductor insufficiency. Our treatment protocol had an 84.4% success rate. The highest risk of failure was in patients with abductor insufficiency with a revision for other etiologies having a success rate of 92%

Instability after total hip arthroplasty is the primary cause for revision surgery and is a frequent complication following revision surgery for any reason (Bozic et al, JBJS 2009). Surgical management of the unstable hip has not been uniformly successful with the best results occurring in those hips in which an identifiable cause of instability can be determined (Daly & Morrey, JBJS 1992). It was these sobering findings that led to the development of and increased use of constrained acetabular components. While the results of revision surgery for instability using constrained components have been encouraging (Shapiro, Padgett, Sculco J Arthroplasty 2003) with a re-dislocation rate of less than 3%, reoperation for other reasons have noted to increase with time. The commonly used tripolar configuration has been susceptible to bearing damage at both the inner and outer bearing surface by the nature of the constrained mechanism (Shah, Padgett, Wright, J Arthroplasty 2009). In addition, we have noted instances of fixation failure directly related to the constrained acetabular device either from loss of implant fixation to the pelvis with or without cement (Yun, Padgett, Dorr, J Arthroplasty 2005). The observation of these failure modes ranging from either fixation failures to overt biomaterial failure have led us to be extremely cautious in the “routine” use of constrained liners in revision THR. Stratification of the recurrent dislocator has been nicely described by Wera et al (J Arthroplasty, 2012). The etiology of dislocation includes: acetabular malposition, femoral malposition, abductor deficiency, impingement, late bearing wear and unknown causes. Implant instability due to malposition, impingement, and poly wear should be revised as appropriate to correct the underlying problem in addition to the use of either larger diameter heads. The emerging use of dual mobility articulations remains to be determined. However, the indiscriminate use of constrained liners should be avoided as the risk of problems outweighs their benefits

Introduction. Recurrent dislocation following total hip arthroplasty (THA) is a complex, multifactorial problem that has been shown to be the most common indication for revision THA. The purpose of this study was to classify causes of instability and evaluate outcomes based on an algorithmic approach to treatment. Methods. Two surgeons performed 75 consecutive revisions for instability. Patients had a mean of 2 (range, 0 to 6) prior operative attempts to resolve their instability. Subjects were divided into 6 types based on etiology of instability: I) malposition of the acetabular component, II) malposition of the femoral component, III) abductor deficiency, IV) impingement, V) late wear, or VI) unclear etiology. Types I/II were treated with revision of the malpositioned component, Type III/VI with constrained liner, Type IV by removing sources of impingement and Type V with liner change. Large (>36mm) femoral heads were used routinely. Results. The causes of instability were Type I: 25 (33%); Type II: 8 (10%); Type III: 28 (37%); Type IV: 7 (9%); Type V: 5 (7%); Type VI: 3 (4%). At a mean of 32.5 months (Range, 24 to 79) 12 patients re-dislocated (15.6%). Among these 12 failures 8 (75%) were in patients with abductor insufficiency (Type III) treated with a constrained liner. Conclusions. The most common causes of instability were cup malposition and abductor insufficiency. Our treatment protocol had an 84.4% success rate. The highest risk of failure was in patients with abductor insufficiency with revision for other etiologies having a success rate of 92%

Introduction. Recurrent dislocation following total hip arthroplasty (THA) is a complex, multifactorial problem that has been shown to be the most common indication for revision THA. The purpose of this study was to classify causes of instability and evaluate outcomes based on an algorithmic approach to treatment. Methods. Two surgeons performed 77 consecutive revisions for instability. Patients had a mean of 2 (range, 0 to 6) prior operative attempts to resolve their instability. Subjects were divided into 6 types based on the etiology of instability: I) malposition of the acetabular component, II) malposition of the femoral component, III) abductor deficiency, IV) impingement, V) late wear, or VI) unclear etiology. Types I/II were treated with revision of the malpositioned component, Type III/VI with a constrained liner, Type IV by removing sources of impingement and Type V with a liner change. Large (>36mm) femoral heads were used routinely. Results. The causes of instability were Type I: 25 (33%); Type II: 8 (10%); Type III: 28 (37%); Type IV: 7 (9%); Type V: 5 (7%); Type VI: 3 (4%). At a mean of 32.5 months (Range, 24 to 79) 12 patients re-dislocated (15.6%). Among these 12 failures, 8 (75%) were in patients with abductor insufficiency (Type III) treated with a constrained liner. Conclusions. The most common causes of instability were cup malposition and abductor insufficiency. Our treatment protocol had an 84.4% success rate. The highest risk of failure was in patients with abductor insufficiency with a revision for other etiologies having a success rate of 92%

Intra-operative complications vary from extremely benign such as glenoid vault penetration to life and limb threatening for example brachial artery injury. Most intra-operative complications can be avoided with careful pre-operative planning, anticipation, and execution. However, even the best planning and execution including fluoroscopic guided reaming cannot prevent all complications. The following intra-operative complications will be discussed in detail in regards to both prevention and management: Glenoid vault penetration, Glenoid component malposition - reverse and primary, Glenoid fracture - reverse and primary, Humeral component malposition - reverse and primary, and Humeral fracture - reverse and primary

Metal-on-metal (MOM) hip arthroplasty has been associated with a variety of new failure modes that may be unfamiliar to surgeons who traditionally perform metal-on-polyethylene THR. These failure modes include adverse local tissue reaction to metal debris, hypersensitivity to metal debris, accelerated wear/metallosis, pseudotumours, and corrosion. A significant number of patients with metal-on-metal hip arthroplasty may present to surgeons for routine followup, concern over their implant, or frank clinical problems. A common issue with MOM hip arthroplasty that can lead to accelerated wear and failure is implant malposition. Malposition of a hard-on-hard bearing can lead to edge loading and accelerated wear at the articular surfaces, which will lead to elevation in blood metal ion levels and metallosis. Distinct from this failure mode is the possibility of metal hypersensitivity, which is believed to be an immunologically mediated reaction to normal amounts of metal debris. Because a modular MOM THR has multiple junctions and tapers that come into contact with one another, there also is the possibility of non-articular metal debris production and corrosion. This type of corrosion reaction can lead to soft tissue destruction not commonly seen with hip resurfacing. Therefore, it is important for orthopaedic surgeons to be aware of the intricacies of following a metal-on-metal hip arthroplasty and to be able to interpret test results such as metal ion levels and cross-sectional imaging. Furthermore, there is a difference in the incidence of problems depending upon the type of implant: hip resurfacing, small-diameter head metal-on-metal total hip replacement, and large diameter head MOM THR. This presentation will discuss the importance of routine monitoring and followup for patients with MOM THR, as well as the utility of measuring blood metal ion levels. The published risk stratification algorithm from the Hip Society will be reviewed

There has recently been an increase in the number of hip replacement procedures performed through an anterior approach. Every procedure has a risk profile, and in the case of a new procedure or technique it is important to investigate the incidence of complications. The aim of this study is to identify the complications encountered in the first 100 patients treated with the minimally invasive anterior approach. This is a case series of the first 100 hips treated and were assessed for complications. These were classified according to the severity and outcome [1]. The 100 hip comprised of 98 patients; 46 males and 52 females with an average operation age on 70.1 (±9.38) years. There were 2 bilateral procedures. Specific patient selection criteria were used. All complications occurred within one month of surgery. Complications such as fracture, deep vein thrombosis (DVT), cup malposition, femoral stem malposition, retained screw, excessive acetabular reaming and skin numbness were noted. Complications associated with fracture were characterised as either periprosthetic or trochanteric. Clinical outcome scores of SF36v2, WOMAC, Harris Hip and Tegner activity score were analysed at pre-operative, 6 months, 12 months 24 months and 36 months intervals. A total of 13 early complications occurred. Of these 13 complications the most common complications were trochanteric fracture, 3 instances (3.00%), periprosthetic fracture, 2 (2.00%), DVT, 2 (2.00%), numbness, 2 (2.00%) and loosening. Other complications recorded were cup malposition, 1 (1.00%), femoral stem malpositon, 1 (1.00%), retained screw, 1 (1.00%) and excessive acetabular reaming, 1 (1.00%). All fractures occurred in patients over the age of 60 years. There were no dislocations. Significant differences (p<0.05) were observed between all clinical outcomes measures pre-operatively and postoperatively (6, 12, 24 and 36 months). The unfamiliarity of the approach, however, increased operating time, and exposure problems, lead to trochanteric fracture

Introduction. Cup malposition in hip arthroplasty and hip resurfacing is associated with instability, accelerated wear, and the need for revision. The current study similarly assesses the variation in cup position using conventional techniques as measured by CT. Methods. We have performed CT-based navigation of hip arthroplasty and revision arthroplasty on a routine basis since 2003 and also use CT imaging to quantify periprosthetic osteolysis. In our image database, we have identified 91 hips in 87 patients (51 female, 36 male) who had a previously conventionally-placed cup on CT imaging. For each hip, cup orientation was determined in operative anteversion and operative inclination (according to the definitions of Murray) using an application specific software application (HipSextant Research Application 1.0.7, Surgical Planning Associates Inc., Boston, Massachusetts). This application allows for determination of the Anterior Pelvic Plane coordinates from a 3D surface model. A multiplanar reconstruction module allows for creation of a plane parallel with the opening plane of the acetabulum and subsequent calculation of plane orientation in the AP Plane coordinate space. Results. The conventionally placed cups ranged from −7.2° to 57.5° in operative anteversion (mean = 30.2°, SD = 11.6°) and 18.4° to 68.1° in operative inclination (mean = 37.6, SD = 8.2°). If a safe zone goal of 27 degrees of operative anteversion (± 10°) and 42 degrees of operative inclination (± 10°) is assumed, 29.7% of hips are out of the safe zone of operative anteversion, and 25.3% of hips are out of the safe zone of operative inclination. 45.1% of all hips are out of the safe zone in either operative anteversion, operative inclination, or both. If a goal of 20° of operative anteversion (± 10°) and 45° of operative inclination (± 10°) is assumed, 55.0% of hips are out of the safe zone in operative anteversion, 44.0% of hips are out of the safe zone in operative inclination, and 70.3% of hips are out of one or both safe zones. Discussion. Most conventionally placed acetabular components are malpositioned and the current study confirms prior reports of the incidence of cup malposition as measure both by CT and plain radiographs. It is curious that most experienced surgeons who perform total hip arthroplasty using conventional methods of cup alignment believe that their accuracy quite good. Yet, multiple objective studies of cup alignment demonstrate that accuracy is quite poor. Since cup malposition is so closely associated with instability, impingement, wear, bearing fracture, osteolysis and loosening, questions remain as to how conventional methods of cup alignment remain an acceptable standard of care in our field

Recently, new metallurgical techniques allowed the creation of 3D metal matrices for cementless acetabular components. Among several different products now available on the market, the Biofoam Dynasty cup (MicroPort Orthopedics® Inc., Arlington, TN, USA) uses an ultraporous Titanium technology but has never been assessed in literature. Coping with this lack of information, our study aims to assess its radiological osteointegration at two years in a primary total hip arthroplasty and compares it to a successful contemporary cementless acetabular cup. This monocentric retrospective study includes 96 Dynasty Biofoam acetabular components implanted between March 2010 and August 2014 with a minimum 2 years radiographic follow-up. Previous acetabular surgery, any septic issue or re-operation for component malposition were exclusion criteria. They were compared to 96 THA using the Trident PSL matched for age, gender, BMI and follow-up. Presence of radiolucencies and sclerotic lines were described on AP pelvis views using the classification of DeLee and Charnley. There was no statistical difference between the two groups concerning demographics and mean follow-up (p> 0.05). Shell's anteversion was similar but inclination was greater in the biofoam group (p=0.006). 27,17% of the Biofoam shells presented radiolucencies in 2 zones or more and 0% of the Trident shells. 11,96% of Biofoam cups showed radiolucencies in the 3 zones of DeLee comparing to 0% of the Trident cups. There was no statistical difference between the Biofoam group (n=54/96) and the Trident PSL group (n=57/96) in pre-operative functional scores for both WOMAC subscales and SF-12. When evaluating last follow-up PROM's, no significant differences were found comparing the entirety of both groups, 56 Biofoam and 51 Trident PSL. No difference was found either when comparing Biofoam patients with ³ 2 zones of radiolucencies (n=15) to the whole Trident group (n=51). This study raises concerns about radiologic evidence of osteointegration of the Biofoam acetabular cup. Nevertheless, these radiological findings do not find any clinical correlation considering clinical scores. Thus, it may question the real meaning of these high-rated radiolucencies, which at first sight reflect a poorer osteointegration. The first possible limitation with this study is an overinterpretation of the radiographs. Nevertheless, both observers were blinded regarding the patients groups and clinical outcomes and there was a strong inter-observer reliability. Although both cohorts were matched on their demographics and were similar on the cup anteversion, we noticed a slightly lower abduction angle in the Biofoam population. It could reduce the bone-implant coverage area and hence hinders the bony integration, but this difference was small and both groups remained in the Lewinneck security zone. Furthermore, even if patients were matched on age, gender, BMI and follow-up, other variables can influence early osteointegration (smoke status, osteoporosis) and have not been controlled even though we have no reasons to think their distribution could differ in the 2 groups. The real clinical meaning of these findings remains unknown but serious concerns are raised about the radiographic osteointegration of the Dynasty Biofoam acetabular components. Concerns are all the more lawful that this implants aim to enhance osteointegration