BACKGROUND. There is no report of additional type of bulk bone grafting (Ad-BG) method with impaction morselized bone graft for reconstruction of shallow dysplastic hip in total hip arthroplasty. The purpose of this study was to define the shallow acetabulum and to evaluate the clinical and radiographic results of primary total hip arthroplasty (THA) with Ad-BG method. MATERIALS and METHODS. With modification of Crowe's classification, shallow dysplasia was defined and classified (Fig. 1). Between October 1999 and August 2008, 120 hips of 302 THAs for dysplastic hip were defined as shallow and Ad-BG was done in 96 hips (80% of shallow hips). For 24 hips with shallow dysplasia, THA were performed by using conventional type of interpositional bulk bone graft (Ip-BG) (8 hips) or without bone graft by using rigid lateral osteophyte. All patients were followed clinically using the Japanese Orthopaedic Association (JOA) score and also Merle d'Aubigne and Postel (M&P) scores in a prospective fashion, and radiographs were analyzed retrospectively. The criteria used for determining loosening were migration or total radiolucent zone between the prosthesis (or bone cement) and host bone. The mean follow-up periods were 8.0 ± 2.3 (5.0–13.5) years. Operative technique. Resected femoral head was sliced with thickness of 1–2 cm, and then a suitable size of the bulk bone block was placed on the lateral cortex of the ilium and fixed by polylactate absorbable screws. Autogenous impaction morselized bone grafting with or without hydroxyapatite granules was performed in conjunction with a cemented socket (Fig. 2). The same surgeon assisted by his colleagues operated all of the cases. RESULTS. No acetabular components were revised except for a case with shallow and Crowe type IV acetabulum. The mean JOA and M&P score for the hips improved from preoperative 39 and 6 points to postoperative 93 and 17 points respectively. Radiographically, the Ad-BGs in most of the cases were remodeled and recognized reorientation within 2 years postoperatively. CONCLUSIONS. The authors report good results of acetabular reconstruction with the use of Ad-BG technique in conjunction with impaction morselized bone graft for shallow dysplastic hip in primary THA. Osteointegration and good clinical outcome were achieved in most of cases. However longer term outcome should be the subject of further investigation

Introduction. Inadequate stability of the baseplate is a leading cause of revision within reverse total shoulder arthroplasty (rTSA). Micromotion between baseplate and bone is commonly used as a pre-clinical indicator for clinical stability (ASTM F2028-14). Finite element analysis (FEA) has been shown to accurately predict baseplate-bone micromotion, but results may be critically dependent on several modeling assumptions. Here, FEA was used to assess the impact of key modeling assumptions related to screw-bone interactions on various rTSA configurations. Methods. FEA with Ansys ver. 16 was used to simulate a fixation experiment. Baseplates of two different sizes (25mm and 28mm diameter), each with a central screw and four peripheral screws, were virtually implanted in a synthetic bone block. Each baseplate was analyzed using 1.5mm and 3.5mm superior-inferior (SI) offsets of the glenosphere center, as well as using four (‘4S’) and two (‘2S’) peripheral screws. A clinically relevant loading of 756N was applied in compression as well as in inferior-to-superior shear direction through the glenosphere (Figure 1A, 1B). Screw-bone block interactions were modeled in three different ways: (1) Threads were defeatured from the peripheral screws, which were bonded to the bone block (b-nt); (2) Threads were modeled, while still assuming bonded contact (b-t); (3) Threads were modeled, with frictional contact between threads-bone block (f-t). Micromotion results (Figure 1C) from all 24 simulations (3 screw-bone interactions × 2 baseplate diameters × 2 SI offsets × 2 screw configurations) were compared. Results. Across all 24 configurations, the f-t screw-bone interaction resulted in increased micromotion relative to the corresponding bonded simulations. Differences between the two bonded simulations varied among configurations (Figure 2). Screw configuration: For all baseplate diameters, SI offsets, and screw-bone interactions, the 4S configuration had less micromotion (7–20%) than the corresponding 2S configuration (Figure 2). SI Offset: For all baseplate diameters, screw configurations, and screw-bone interactions, the 1.5mm SI offset configuration predicted higher micromotion than the corresponding 3.5mm SI offset configuration (increase of 5–18%), except for the 25mm baseplate in b-nt condition (12–19% decrease) (Figure 3A). Baseplate diameter: For all screw configurations and SI offsets, the f-t modeling assumption resulted in decreased micromotion (5–12%) for the 28mm baseplate as compared to the 25mm baseplate. This trend was reversed for select screw configurations and SI offsets for the other two (b-nt, b-t) modeling assumptions (Figure 3B). Discussion. This study highlights the importance of FEA model fidelity (the level of rigor with which the screw-bone interface is modeled) on evaluating differential performance between rTSA baseplate configurations within a single design family. Three different levels of rigor were considered, based on whether or not the screw threads were explicitly modeled, and on the level of friction allowed between the screw and the bone block. Results highlight that answers to basic questions on relative baseplate performance (e.g. is a 25mm or 28mm baseplate more stable?) are sensitive to these assumptions, and require adequate model validation. Increased care should be taken when conducting evaluations across multiple device families, when additional variables (e.g. screw pitch/torque) are present that could confound analyses

This paper reports a series of comparative tests in-vitro that examined how lateral meniscectomy and meniscal allografting affected tibio-femoral joint contact pressures. 8 Cadaver knees (age range 81 – 98 years) were loaded in axial compression in an Instron materials testing machine up to 700N for 10 seconds and pressure maps obtained from the lateral compartment using Fuji Prescale film inserted below the meniscus. This was repeated after meniscectomy, then after meniscal allografting with fixation by a bone plug for the insertional ligaments, plus peripheral sutures. Finally, the pressure when the allograft was secured by peripheral sutures alone was measured. Meniscectomy caused a significant increase in peak contact pressures (p=0.0002). Both of the reconstructive methods reduced the peak contact pressures significantly below that of the meniscectomised knee (p=0.0029 with bone block; p=0.0199 with sutures alone). A significant difference was not found between the peak contact pressures after the reconstructions and that of the intact knee (p=0.1721 with bone block; p=0.0910 with sutures alone). The peak pressures increased slightly when the allografts were converted from bone block to suture-only fixation (p=0.0349). The principal finding was that both of the meniscal allograft insertion techniques reduced the peak contact pressure significantly below that of the meniscectomised knee, so that it did not then differ significantly from the peak contact pressure in the intact knee. When the two fixation methods were compared, the loss of the bone plug attachment caused a small increase in peak pressure. This study suggests that meniscal allografting should have a chondroprotective effect and that there is a small advantage from adding bony fixation to suture fixation

To evaluate the efficacy of using a novel button-suture construct in place of traditional screws to provide bone block fixation for the Latarjet procedure. Four paired cadaveric shoulders (n=8) were denuded, with the exception of the conjoint tendon on the coracoid, and were potted. A 15% anterior glenoid bone defect was simulated. Right and left specimens were randomised into two groups: double-screw versus quadruple-button Latarjet reconstruction techniques. A uniaxial mechanical actuator loaded the Latarjet reconstructed glenoid articular surface via a 47mm diameter metallic hemisphere. Cyclic loading between 50–200N was applied to the glenoid at a rate of 1Hz for 1000 cycles. Testing was repeated three times for conjoint tendon loads of 0N, 10N and 20N. The relative positions of three points on the inferior, central and superior edges of the coracoid bone fragment were optically tracked with respect to a glenoid coordinate system throughout testing. Screw and button constructs were compared on the basis of maximum relative displacement at these points (RINF, RCENT, RSUP). Statistical significance was assessed using a paired-samples t-test in SPSS. When conjoint tendon loading was not present the double screw and quadruple button constructs were not significantly (P>0.779) different (0N: RINF: 0.11 (0.05)mm vs. 0.12 (0.03)mm, RCENT: 0.12 (0.04)mm vs. 0.12 (0.03)mm, RSUP: 0.13 (0.04)mm vs. 0.12 (0.03)mm). Additionally, the double screw construct was not found to differ (P>0.062) from the quadruple button in terms of resultant coracoid displacement for all central and superior points, regardless of conjoint loading (10N: RCENT: 0.11 (0.03)mm vs. 0.19 (0.05)mm, RSUP: 0.11 (0.01)mm vs. 0.18 (0.04)mm; 20N: RCENT: 0.13 (0.01)mm vs. 0.30 (0.13)mm, RSUP: 0.13 (0.03)mm vs. 0.26 (0.14)mm). It was only for the inferior point with conjoint loading of 10N and 20N that the double screw construct began to produce significantly lower displacements than the quadruple button (10N: RINF: 0.11 (0.03)mm vs. 0.23 (0.05)mm, P=0.047; 20N: RINF: 0.12 (0.02)mm vs. 0.39 (0.15)mm, P=0.026). The results of the screw and button constructs when conjoint tendon loading was absent suggest that the button may be a suitable substitute to the screw when the coracoid is used as a bone block. Due to the small resultant displacements (max: screw = 0.19mm, button = 0.52mm), it is suggested that buttons may also act as a substitute to screws for Latarjet procedures, provided conjoint tendon overloading is minimised during the post-operative graft healing period. These in-vitro results support the in-vivo results of Boileau et al (2015) that demonstrated the suture-button technique to be an excellent alternative to screw fixation Latarjet, with graft healing in 91% of their subjects

Introduction. Loosening of the baseplate is one of the most common causes of failure in Reverse Shoulder Arthroplasty. To allow osteo-integration to occur and thus provide long-term stability, initial screws fixation plays a pivotal role. In particular, tightening torque and force of nonlocking screws are two parameters that are considered to have a clear impact on implant stability, yet the relation is not fully understood. For this reason, this study aims to define an experimental set-up, to measure force and torque in artificial bone samples of different quality, in order to estimate ranges of optimal surgical values and give guidelines to maximize screw fixation and therefore initial implant stability. Methods. A custom-made torque sensor (Figure 1a) was built and calibrated using a lever deadweight system. To measure the compression force generated by the screw head, three thin FlexiForce sensors (Tekscan, South Boston, US) were enclosed between two 3D printed plates with a central hole to allow screw insertion (Figure 1b). The tightening force, represented by the sum of the three sensors, was calibrated using a uniaxial testing machine (Zwick/Roell, Ulm, Germany). Multiple screw lengths (26mm, 32mm and 47mm) were selected in the protocol. Synthetic bone blocks (Sawbones; Malmö, Sweden) of 20 and 30 PCF were used to account for bone quality variation. To evaluate the effect of a cortical bone layer, for each density three blocks were considered with 0 mm (no layer), 1.5 mm and 3 mm of laminate foam of 50 PCF. The holes for the screws were pre-drilled in the same way as in the operation room. For each combination of screw dimensions and bone quality, ten measurements were performed by acquiring the signal of the insertion torque and tightening force until bone breaking. Results. The typical output signal shows a maximum in the torque and force measurements, corresponding to bone breaking. After failure, a drop in the torque is visible, while a residual force remains present. For the base case (20 PCF), both torque and force show increasing mean values with longer screws, passing from 0.39 Nm (26mm) to 1.12 Nm (47mm) and from 180 N (26mm) to 419 N (47mm) respectively. Similar patterns were observed when the cortical layer was present or the bone quality was increased. Discussion. The findings of this study demonstrate that tightening force and torque are strongly impacted by bone quality and screw length. As main outcome, the maximum torque values could be used in clinical practice as a safety threshold for the surgeon. Compression force could also be used as input parameter in stability predictions of numerical models. Since only bone substitute was used, future research should include the extension to cadaveric bones. For any figures or tables, please contact authors directly

Introduction. Acetabular component loosening has been one of the factors of revision of total hip arthroplasty (THA). Inadequate mechanical fixation or load transfer may contribute to this loosening process. Several reports showed the load transfer in the acetabulum by metal components. However, there is no report about the influence of the joint surface on the load transfer. We developed a novel acetabular cross-linked polyethylene (CLPE) liner with graft biocompatible phospholipid polymer(MPC) on the surface. The MPC polymer surface had high lubricity and low friction. We hypothesized the acetabular component with MPC polymer surface (MPC-CLPE) may reduce load transfer in the acetabulum compared to that of the by CLPE acetabular component without MPC. Methods. We fixed the three cement cup with MPC-CLPE (Group M; sample No.1–3) and three cement cup with CLPE (Group C; sample No.4–6) placed in the synthetic bone block with bone cement with a 0.10mm thick arc-shaped piezoresistive force sensor, which can measure the dynamic load transfer(Tekscan K-scan 4400; Boston). (Fig 1) A hip simulator (MTS Systems Corp., Eden Prairie, MN) was used for the load transfer test performed according to the ISO Standard 14242-1. Both groups had same inner and outer diameter s of 28 and 50mm, respectively. A Co–Cr alloy femoral head with a diameter of 28 mm (K-MAXs HH-02; KYOCERA Medical Corp.) was used as the femoral component. A biaxial rocking motion was applied to the head/cup interface via an offset bearing assembly with an inclined angle of +20. Both the loading and motion were synchronized at 1 Hz. According to the double-peaked Paul-type physiologic hip load, the applied peak loads were 1793 and 2744 N described in a previous study. The simulator was run 3 cycles. We recorded both the peak of the contact force and the accumulation of the six times load in total. Secondly, we calculated the mean change of the load transfer. We used the Student t-test. P value < 0.05 was used to determine statistical significance. We used EZR for statistical analysis. Results. The mean of total accumulation of the load transfer in the group M is significantly lower than that of in the group C. (7037±508 N vs 11019±1290 N, P<0.0001). The peak of load in the group M was also significantly lower than that in the group C. (1024±166 N vs 1557±395 N) (Fig 2)The mean of the change of the load transfer in the group M is significantly lower than that of in the group C. (2913±112 N vs 4182±306 N) (Fig 3). Conclusion. The acetabular component with MPC surface could reduce and prevent the radical load transfer change toward to the acetabulum compared to CLPE acetabular component without MPC. For any figures or tables, please contact the authors directly

Hypothesis. Recurrent shoulder dislocation is associated with bony defect of the glenoid rim, commonly seen along with bankart tear - a soft tissue injury of glenoid labrum. This cadaveric study compares the bone block effect of coracoid transfer using using two common techniques, Classical Latarjet technique and the Congruent-Arc Latarjet. We hypothesized that the force needed to dislocate the shoulder would be greater in Congruent Arc technique than the Classical Latarjet, because of increased contact surface area as a result of greater linear dimensions. Material and methods. We dissected 14 cadaveric shoulders. A bony Bankart lesion was created in form of an inverted pear glenoid. The humeral head was attached to a pulley system that was sequentially loaded until the shoulder dislocated anteriorly. The force needed to dislocate was noted. This was repeated after coracoid transfer with two common techniques, Classical Latarjet technique and the Congruent-Arc Latarjet. Results. The mean force required to dislocate shoulder post-Classical Latarjet technique was 325.71N, compared to 123.57 N in uncorrected shoulder. Similarly, the mean force required to dislocate shoulder post Congruent-Arc Latarjet technique was 327.14 N compared to 123.57 N in uncorrected shoulder. The two-tailed P value in either case was less than 0.0001, thus statistically significant. Unpaired t-test was done to compare the force required to dislocate the shoulder post procedure. Mean force required to dislocate shoulder post-Classical Latarjet, was 325.7N compared to 327N in post-Congruent Arc. The two-tailed P value equals 0.9020 and the 95% confidence interval was from −25.05 to 22.19, thus the difference was not statistically significant. Conclusion. The results confirm that both (Classical and Congruent-Arc Latarjet) techniques are good for addressing the shoulder instability, however bone block effect provided by one is not superior to other

INTRODUCTION. Finite element analysis (FEA) is widely used to study micromotion between the glenoid baseplate and bone, as a pre-clinical indicator for clinical stability in reverse total shoulder arthroplasty (rTSA). Various key parameters such as the number, length, and angle of screws have been shown to influence micromotion [1]. This study explores the influence of screw preloads, an insufficiently studied parameter. Specifically, two rTSA configurations with 18mm and 48mm peripheral screws (PS) were analyzed without screw preloads, followed by analysis of the 48mm PS configuration with an experimentally measured screw preload. METHODS. FEA models were created to simulate a fixation experiment inspired by ASTM F2028-14. The rTSA configurations used here have a superior and an inferior PS. The assemblies were virtually implanted into a synthetic bone block as per surgical technique. Sliding contacts were defined to model the interface between screw threads-bone, and between baseplate-bone. To determine the screw preload experimentally, the 48mm screw (n=5) was inserted through a hole in a metal plate, which rested on top of a Futek washer load cell, placed on top of the foam block with a predrilled pilot hole (Figure 1). The screw was inserted using a torque driver until the average human factors torque for the screw driver handle was reached. The resulting axial compressive load due to screw insertion was measured by the washer load cell. Two step analyses were performed using Ansys version 17.2 for 18mm and 48mm PS, where 756N axial and shear loads were applied sequentially. The model with the 48mm PS was then analyzed in a four step analysis; preload inferior and superior screws, followed by applying the axial and shear loads (Figure 2). Peak overall micromotion including tangential and normal components at the baseplate-bone interface was compared for all three models. RESULTS. From the experimental study, the mean screw preload for the 48mm screw was determined to be 141±8 lbs. Peak micromotion was predicted at the inferior edge of the baseplate (Figure 3A). In the two models without screw preloads, the model with the 48mm PS predicted 42% lower micromotion than the model with the 18mm PS. The 48mm PS model predicted 63% further reduction in micromotion by including the preload for the two PS. Figure 3B presents the micromotion comparison between these three models. DISCUSSION. This study demonstrates the significant influence that screw preload can have on evaluating either absolute values or differential performance of rTSA micromotion within the same design family. It further demonstrated that the inclusion of preload in simulation can have as much (or greater) impact on micromotion as other key parameters such as shorter versus longer screws. These findings indicates that it is important to include appropriate values of screw preloads in simulations when comparing designs with different number of peripheral screws or studying the effects of including a central screw on rTSA micromotion

The shoulder is the least constrained of all joints of the body and is more susceptible to injury including dislocation. The rate of recurrent instability following primary stabilization procedure at 10 years of follow-up ranged from 3.4 to 35 %. We describe the outcomes of 74 patients who underwent knotless arthroscopic anterior stabilisation using 1.5 mm Labral Tape with 2.9mm Pushlock anchors for primary anterior instability. We performed a retrospective analysis of patients who underwent surgery for post-traumatic recurrent anterior instability for 2 years by a single surgeon. Patients with glenoid bone loss, >25% Hill Sachs lesion, posterior dislocation, paediatric age group and multidirectional instability were excluded from this study. Over 90% of our case mix underwent the procedure under regional block anaesthesia and was discharged on the same day. The surgical technique and post-operative physiotherapy was as per standard protocol. Outcomes were measured at 6 months and 12 months. Of the 74 patients in our study, we lost 5 patients to follow up. Outcomes were measured using the Oxford Shoulder Score apart from clinical assessment including the range of motion. We noted good to excellent outcomes in 66 cases using the Oxford Instability Scores. All patients achieved almost full range of motion at the end of one year. Our cumulative Oxford Instability Score (OIS) preoperatively was 24.72 and postoperatively was 43.09. The Pearson correlation was .28. The t Critical two-tail was 2.07 observing the difference between the means of the OIS. Complications included recurrent dislocation in 2 patients following re-injury and failure of procedure due to recurrent instability requiring an open bone block procedure in one case. We had no reported failures due to knot slippage or anchor pull-out. We publish the largest case series using this implant with distinct advantages of combining a small bio absorbable implant with flat braided, and high-strength polyethylene tape to diminish the concern for knot migration and abrasive chondral injury with the potential for earlier rehabilitation and a wider footprint of labral compression with comparative outcomes using standard techniques. Our results demonstrate comparable and superior results to conventional suture knot techniques for labral stabilization

Acetabular reconstruction of extensive bone defect is troublesome in revision total hip arthroplasty (rTHA). Kerboull or Kerboull type reinforcement acetabular device with allobone grafting has been applied since 1996. Clinical results of the procedure were evaluated. Patients. One hundred and ninety-two consecutive revision total hip arthroplasties were performed with allograft bone supported by the Kerboull or Kerboull type reinforcement acetabular device from 1996 to 2009. There were 23 men and 169 women. Kerboull plates were applied to 18 patients, and Kerboull type plates to 174. The mean follow up of the whole series was 8 years (4–18years). Surgical Technique. The superior bone defect was reconstructed principally by a large bulky allo block with plate system. Medial bone defect was reconstructed by adequate bone chips and/or sliced bone plates. After temporally fixation of bulky bone block with two 2.0mm K-wires, it was remodeled by reaming to fit the gap between host bone and plate, followed by fixation to the iliac bone by screws. Finally, residual space of the defect between host bone and the fixed plated was filled up with morselized cancellous bones, bone chips, and/or wedged bony fragments with impaction. This method was sufficiently applicable to AAOS Typeâ�, II, and III bone defects. In case of AAOS Typeâ�£, the procedure was also available after repairing discontinuation between distal and proximal bones by reconstrusion plate or allografting with tibial bone plates or sliced femoral head. Results. Nine patients (4.7%) required revision surgery (infection 5, breakage 3, and malalignment 1). The plate breakage was observed in 8 joints (4.2%). Three patients had no symptoms after the breakage. Three required revision, but the other cases were carefully observed without additional surgical intervention. Ten-year survival rate by Kaplan-Meier method was 96.6% when the endpoint was set revision by asceptic loosning. Conclusions. This study indicated that acetabular allograft reconstructions reinforced by Kerboull or Kerboull type acetabular device were able to recover bone stock with anatomic reconstruction of femoral head center, thus providing satisfactory clinical results in middle term period

Introduction. In addition to traditional posterior-stabilized (PS) designs with cam-post articulations, there are two new design concepts used in total knee replacement (TKR) to “substitute” for cruciate ligament function and restore anterior-posterior stability. These include i) guided-motion PS designs with a modified cam-post that is less restrictive to axial rotation; and ii) non-PS designs that incorporate progressive articular congruency to substitute the function of the resected anterior cruciate ligament (ACL-substituting). Early post-marketing surveillance of such new TKR designs is valuable because instability, loosening, and high complication rates within the initial 5 year follow-up interval have proven problematic for some design. This study reports the early clinical performance of sequential patients implanted with a new ACL-substituting TKR design at a German Center of Excellence for Arthroplasty (EPZ-Max) hospital. Methods. This is a single-site, multi-surgeon retrospective study with Institutional Review Board approval. The nine surgeons involved all used uniform surgical techniques, including a mid-vastus approach, PCL preservation with a bone block, tibial component alignment with the natural tibial slope, no patellar resurfacing, and cement fixation. All patients meeting the following inclusion criteria were contacted by phone: a) primary TKR from July 2008-June 2009; b) implanted with an ACL-substituting design (3D Knee™, DJO Surgical); c) no prior knee arthroplasty; and d) willing to consent to participate. Recorded outcomes at the 5 year follow-up interval included range of motion, Knee Society knee/function scores (KSS), and radiographic results (alignment, radiolucent lines, osteolysis). Additional surgery was classified as “revision” (metal components removed) or “reoperation” (metal components not removed). Results. Out of 166 sequential patients, a study cohort of 69 patients (84 TKR) consented to participate. Average follow-up was 6.2+0.6 (4.7–7.3) years. Maximum flexion averaged 115°+9° (85°–145°), including 39% at >120°. The TKR had stable function and average KSS scores of 94 (knee) and 94 (function). There were four patients (5 TKR, 6.3%) with function scores of <60 points who had considerable pre-operative extension lags (>10°) that lingered (5°–10°) at follow-up. No TKR had evidence of osteolysis or loosening. Non-progressive radiolucent lines were evident post-operatively in 10 TKR and in one additional TKR at last follow-up. Seven (8.3%) TKR required reoperation or revision. Five TKR in the 0–5 year interval required reoperation to treat acute infection, progressive patellar arthritis, and traumatic patellar fracture, and revision to treat pain of unknown etiology (2 TKR revised at another hospital). Two TKR in the 5–6 year interval required revision arthroplasty to treat pain associated with a loose tibial insert screw and unknown symptoms (1 TKR revised at another hospital). Conclusion. This new ACL-substituting design incorporates progressive congruency in the lateral compartment. These data, combined with previous studies (Table 1), provides evidence that this ACL-substituting TKR design restores stability while being robust to surgical and patient variations. These results for a fixed-bearing, non-PS TKR design are supported by international registry data from more than 370,000 TKR in six countries, which demonstrate that survivorship of fixed-bearing cruciate-retaining TKR designs is significantly higher than posterior-stabilized TKR designs, both with and without patella resurfacing

The management of shoulder instability has changed a great deal in the last five years due to a better understanding of the biomechanics of the shoulder and the use of arthroscopic surgery. It is essential to understand the anatomy of the labrum and bony structures of the shoulder joint, as well as the contribution of these structures as well as the Rotator Cuff to stability in the different positions of the arm. The history and examination still remains the most important diagnostic tool and a thorough history and examination cannot be over-emphasised. MR Arthrography is the investigation of choice in confirming the diagnosis of instability while a CT scan may be required if there is significant bony damage. The most controversial topic is that of the first time dislocator. If there is a significant labral tear then the options of an arthroscopic labral repair or external rotation brace need to be considered. In the absence of a labral tear then physiotherapy is the treatment of choice. For recurrent dislocators, the results of arthroscopic labral repairs with capsular plication techniques are approaching those of the gold standard open stabilisation. If, however, there is significant bony damage to the glenoid or humeral head then a bone block procedure may be the treatment of choice. Rotator Cuff tears need to be excluded in older patients with instability and often in such cases an arthroscopic procedure to deal with the Rotator Cuff and Labrum can be done simultaneously

Introduction. Aseptic glenoid loosening is a common failure mode of reverse shoulder arthroplasty (rTSA). Achieving initial glenoid fixation can be a challenge for the orthopedic surgeon since rTSA is commonly used in elderly osteoporotic patients and is increasingly used in scapula with significant boney defects. Multiple rTSA baseplate designs are available in the marketplace, these prostheses offer between 2 and 6 screw options, with each screw hole accepting a locking and/or compression screw of varying lengths (between 15 to 50mm). Despite these multiple implant offerings, little guidance exists regarding the minimal screw length and/or minimum screw number necessary to achieve fixation. To this end, this study analyzes the effect of multiple screw lengths and multiple screw numbers on rTSA initial glenoid fixation when tested in a low density (15pcf) polyurethane bone substitute model. Methods. This rTSA glenoid loosening test was conducted according to ASTM F 2028–17; we quantified glenoid fixation of a 38mm reverse shoulder (Equinoxe, Exactech, Inc) in a 15 pcf low density polyurethane block (Pacific Research, Inc) before and after cyclic testing of 750N for 10k cycles. To evaluate the effect of both screw fixation and screw number, glenoid baseplates were constructed using 2 and 4, 4.5×18mm diameter poly-axial locking compression screws (both n = 5) and 2 and 4, 4.5×46mm diameter poly-axial locking compression screws (both n = 5). A two-tailed unpaired student's t-test (p < 0.05) compared prosthesis displacements to evaluate each screw length (18 vs 46mm) and each screw number (2 vs 4). Results. All glenoid baseplates remained well-fixed after cyclic loading in the low density bone substitute block, regardless of screw length or screw number. As described in Table 1, the average pre- and post-cyclic displacement for baseplates with 18mm long screws was significantly greater than that of baseplates with 46mm long screws in both the A/P and S/I directions, with exception of displacements for 4 screws S/I-pre cyclic and 2 screws A/P-post cyclic loading. As described in Table 2, the average pre- and post-cyclic displacement for all baseplates with 2 screws was significantly greater than that of all baseplates with 4 screws, regardless of screw length in the A/P and S/I directions. Discussion and Conclusions. These results of this study demonstrate that rTSA glenoid baseplate fixation is impacted by both the number of screws and by the length of screws, with longer screws and more screws associated with significantly better initial fixation. However, it should be noted that none of the tested devices catastrophically failed in this non-defect/low-density model, demonstrating that adequate fixation can be achieved with as little as 2×18mm screws for some baseplate types. Care should be made when extrapolating these results to that of other designs. This study is limited by its use of only one implant design and by its use of a polyurethane substrate without any defect; future work should evaluate the effect of screw length and screw number in with multiple different prostheses in different densities of bone with and without defects

Injuries to the infra-patella branch of the saphenous nerve on harvesting Bone-Patella Tendon-Bone (BPB) autograft commonly cause anterior knee pain. The purpose of this study is to investigate the possibility of harvesting a good BPB graft without injury to the nerve by using double mini-incision. Twelve adult cadaveric knees, with two vertical incisions of 25mm, one over the inferior pole of the patella, and the other over the tibial tuberosity were prepared. The tibial bone block was harvested, with preservation of the para-tendon, making a subcutaneous tunnel proximally and stripped to dissect the middle 1/3 of the patella tendon. The graft was then detached after harvesting the patella bone block, and examined for size and quality. The knees were finally dissected to check the relationship of the incisions with the infra-patella branch, and see if it was injured. All BPB grafts were found to have good tendon qualities of average 9.5mm in width. The tibial bone plug is of average 25mm in length and 10mm in width, while the patella bone plug is of average 22mm in length & 9mm in width. All 12 knees have 2 infra-patella branches, with the proximal branch running at averaged distance of 23mm distal to the proximal incision, while the distal branch lying at averaged distance of 11mm proximal to the distal incision. 2 out of the 12 distal branches were injured by the distal incision. Double-mini incision allows harvesting of a consistently good quality BPB graft with preservation of the infra-patella branch of the saphenous nerve

A unique, laterally stabilized design concept (3D Knee-DJO Surgical, Inc) for total knee arthroplasty (TKA) without traditional post and cam construct was developed to allow surgeons to resurface the arthritic knee while choosing to maintain or sacrifice the posterior cruciate ligament (PCL). Reported complications with current ‘post and cam’ designs of PCL-substituting TKRs include higher polyethylene wear associated with cam-post impingement, increased bone interface shear stresses, and more distal femoral bone resection making revisions more complex and problematic. The effectiveness of this laterally stabilized TKA design has been extensively studied biomechanically using both in-vitro and in-vivo methods. It was hypothesized that for this total knee arthroplasty design; the mid-term clinical, radiographic and functional results would be the same for patients having two different surgical techniques in which the posterior cruciate ligament was either completely retained or completely resected. This study reports on eight year clinical results as well as in-vivo fluoroscopic results and retrieval data. Reported are 159 patients with 116 knees done by a surgeon who preserved the PCL with a bone block technique and 43 knees by a second surgeon who completely resected the PCL. Clinical results did not statistically differ between the two groups and found Knee Society Scores of 96 for Pain and 91 for Function. Average ROM was measured at 124 degrees. Comparative fluoroscopic imaging analysis of in-vivo dynamic flexion activities of thirty-three (20 PCL-preserved and 13 PCL resected) knees was performed demonstrating stable performance and only small (non-significant) mechanical differences. Analysis of two unrelated groups of tibial polyethylene inserts, the first retrieved from patients after 1–4 years in-vivo function (n = 14) and the second after in-vitro knee wear simulation (n = 4) showed low wear rates with no delamination. There was only one failure for mechanical loosening in the cruciate resected group and radiolucent lines of greater than 2 mm were only seen in 4% with none being progressive. Kaplan-Meier Survivorship, using mechanical loosening as the end point, was 99.2% at an average of 8.8 years. In summary, this laterally stabilized TKR design offers a very good alternative to standard ‘post and cam’ PCL sacrificing TKRs while still giving surgeons the ability to maintain the PCL if desired

Background. Tibiotalocalcaneal arthrodesis is an important salvage method for patients with complex hindfoot problems including combined arthritis of the ankle and subtalar joints, complex hindfoot deformities and failed total ankle arthroplasty. The aim of this study was to report the elective results of combined subtalar and ankle arthrodesis using one design of dynamic retrograde intramedullary compression nail-the T2 Ankle Arthrodesis Nail(Stryker). Methods. Retrospective review identified 53 consecutive patients who had 55 tibiotalocalcaneal arthrodesis procedures by two surgeons(ITS and NJT) using T2 Ankle nail fixation. 3 patients died of unrelated causes before follow up was complete which left 50 patients(52 nails); the largest consecutive series in the use of this device. Mean follow up was 23.5(3–72) months with the average age of patients being 61(range 22–89) years. An 84% response was achieved to a function and patient satisfaction questionnaire. Main indications for treatment were combined ankle and subtalar arthritis(63%-33/52) or complex hindfoot deformities(23%-12/52). Outcome was assessed by a combination of Clinical notes review, clinical examination, and telephone questionnaire. Results. 46 patients(83.6%) achieved union at a mean time of 3.7 months.8 patients required an allograft(femoral head) bone block procedure. 4 patients(10%) subjectively thought that the procedure was of no benefit or had a poor result whilst 35(83%) had a good or excellent result. The mean visual analog scale(VAS) score for preoperative functional pain was 7.1 compared to the mean post operative(VAS) score of 1.9(p< 0.001). Complications consisted of 2 amputations, 2 deep infections and 5 removals of broken or painful screws. The use of preoperative functional aids and orthotics dropped from 32% to 18% and 22% to 18% respectively. Conclusion. This device and technique is a safe and effective treatment of hindfoot arthrosis and deformity giving reliable compression and subsequent fusion with excellent results in terms of patient satisfaction and pain relief

Tibiotalocalcaneal arthrodesis is an important salvage method for patients with complex hindfoot problems including combined arthritis of the ankle and subtalar joints, complex hindfoot deformities and failed total ankle arthroplasty. The aim of this study was to report the elective results of combined subtalar and ankle arthrodesis using one design of dynamic retrograde intramedullary compression nail-the T2 Ankle Arthrodesis Nail(Stryker). Retrospective review identified 53 consecutive patients who had 55 tibiotalocalcaneal arthrodesis procedures by two surgeons(ITS and NJT) using T2 Ankle nail fixation. 3 patients died of unrelated causes before follow up was complete which left 50 patients(52 nails); the largest consecutive series in the use of this device. Mean follow up was 23.5(3-72) months with the average age of patients being 61(range 22-89) years. An 84% response was achieved to a function and patient satisfaction questionnaire. Main indications for treatment were combined ankle and subtalar arthritis(63%-33/52) or complex hindfoot deformities(23%-12/52). Outcome was assessed by a combination of Clinical notes review, clinical examination, and telephone questionnaire. 46 patients(83.6%) achieved union at a mean time of 3.7 months. 8 patients required an allograft(femoral head) bone block procedure. 4 patients(10%) subjectively thought that the procedure was of no benefit or had a poor result whilst 35(83%) had a good or excellent result. The mean visual analog scale(VAS) score for preoperative functional pain was 7.1 compared to the mean post operative (VAS) score of 1.9(p<0.001). Complications consisted of 2 amputations, 2 deep infections and 5 removals of broken or painful screws. The use of preoperative functional aids and orthotics dropped from 32% to 18% and 22% to 18% respectively. This device and technique is a safe and effective treatment of hindfoot arthrosis and deformity giving reliable compression and subsequent fusion with excellent results in terms of patient satisfaction and pain relief

Introduction:. In posterior cruciate ligament-retaining total knee arthroplasty (CR-TKA), a small bone block (bony island) is often preserved to protect the attachment of the posterior cruciate ligament (PCL), which might be troublesome. In contrast, we prefer to resect the tibial plateau completely to facilitate the surgical procedure. However, there is concern over the increase of the flexion gap due to partial detachment of the PCL. The purpose of the present study is to evaluate the influence of bony island resection on the flexion gap. Methods:. The subjects were 20 consecutive patients who underwent posterior cruciate ligament-retaining total knee arthroplasty for varus osteoarthritis. There were 18 women, two men, with a mean age of 71.8 years (range, 62–82 years). All operations were performed using posterior cruciate ligament-retaining prosthesis (MERA Quest Knee System, Senko Medical Instrument Manufacturing, Tokyo) by the same senior author with a measured resection technique. The knees were exposed with a medial parapatellar approach. The distal femur was cut and the tibial plateau resection was made with preserving the bony island. The central joint gaps in 90° flexion and full extension were measured using a tensioning device (Offset Repo-Tensor, Zimmer, Warsaw, IN) at 40-lb distracting force. Then, after the resection of the bony island, the central joint gaps were measured by the same method. In addition, the posterior tilt of the tibial resection and the depth of the lateral tibial cut were measured. Results:. The flexion gaps before and after the resection were 18.1 ± 0.4 and 18.4 ± 0.5 mm, respectively, and there was no statistical difference (p = 0.07) [Fig. 1]. Similarly, the extension gap did not increase significantly before and after the resection (20.8 ± 0.6 and 21.0 ± 0.6 mm; p = 0.81) [Fig. 2]. The mean posterior tilt was 6.0°, and the mean depth was 10.4 mm. Discussion:. The PCL is the largest and strongest ligament among the knee ligaments. It mainly works as the first stabilizer against posterior laxity, and it has been reported to perform as the second stabilizer against valgus laxity in mid-flexion. Accordingly, we think that preserving the PCL leads to postoperative joint stability in total knee arthroplasty. However, bony island preservation, which is done in CR-TKA, often results in fractures of basal part of the island. Our procedure is comparatively easy, but it cannot avoid the problem of partial detachment of the PCL. The PCL is comprised of two bundles: the anterolateral bundle (ALB) and the posteromedial bundle (PMB). As for the attachments of the bundles, an anatomical study has reported that the locations of the centers of the ALB and PMB were 1.5 ± 0.8 and 6.0 ± 2.0 mm, respectively from the tibial plane. Therefore, considering our tibial resection, it suggests that the distal part of the ALB attachment and the most part of PMB attachment are preserved, which is supported by the results of our study. Conclusions:. Bony island resection can be easily performed and preserve the PCL function

Introduction. Modern acetabular cups require a convenient bone stock for sufficient cup fixation. Thereby, fixation stability is influenced by the chosen interference fit of the acetabular cup, the cup surface structure, circularity of the reamed acetabulum and by the acetabular bone quality. The ideal implantation situation of the cup is commonly compromised by joint dysplasia and acetabular bone defects. The aim of the present experimental study was to characterise implant fixation of primary acetabular cups in case of definite acetabular cavity defects. Materials and Methods. For the experimental determination bone substitute blocks (100 × 100 × 50 mm) made of polymethacrylimide (PMI) foam with a density of 7 pcf were used. The created acetabular defect situations were derived from the defect classification according to Paprosky. The defect geometries in the PMI foam blocks were realised by a CNC drilling machine. Thereby the defects are described in the dorso-ventral direction by the angle α and in medio-lateral direction by the angle β (given as angle combination α/β) related to the centre of rotation of the reamed cavity. For the lever-out tests the defect types IIb and IIIa (each with different α and β angles) were considered and compared to the intact fixation situation. Therefore, a macrostructured titanium cup (Allofit, Zimmer GmbH, Wintherthur, Switzerland) with an outer diameter of 56 mm were displacement-controlled (v = 20 mm/min) pushed into the 2 mm diametric under reamed PMI-foam cavities. Three cups were inserted until the cup overhang pursuant to surgical technique was reached. Subsequently the cups were displacement-controlled (v = 20 mm/min) levered out via a rod which was screwed into the implant pole by perpendicular displacement (U. axial. ) of the rod in direction of the defect aperture. The lever-out moments were calculated by multiplying the first occurring force maximum (F. max. ) with the effective lever arm length (l. lever. ), whereby moments caused by the deadweight of the rod were considered. Primary stability was defined by the first maximum lever-out moment. Results. The calculated lever-out moments were in a range from 15.5 ± 1.4 Nm to 1.4 ± 0.5 Nm. Defects with a 90° dorso-ventral opening angle showed 57 ± 17% lower lever-out moments. Defects with a 120° dorso-ventral opening angle showed 80 ± 6% lower lever-out moments compared to the cup fixation into intact cavities. Moreover, medio-lateral angles greater than 20° reduced the lever-out moment by 79 ± 12% compared to the intact cavities. Conclusion. The determined lever-out moments underline the reduction of fixation stability of acetabular cup by loss of circumferential rim and absent of superior wall support of the acetabular bone. Thereby, the fixation stability is influenced by the degree of dorso-ventral and medio-lateral defect manifestation. Hence, the fixation stability depends on the cavity surface and in particular the surface of the bone-implant interface in the fixation zone of the acetabular cup Thus, dorso-ventral defect sizes with greater opening angle than 60° and medio-lateral defect sizes greater than 20° are critically for sufficient fixation of primary acetabular cup implants

Introduction. Reverse Total Shoulder Arthroplasty (rTSA) is currently advised against in patient populations with movement disorders, due to potential premature failure of the implants from the use of walking assistive devices. The objective of this study is to measure the amount of displacement induced by the simulated loading of axillary crutches on a rTSA assembly in a laboratory mimicking immediate postoperative conditions. Methods. 8 reverse shoulder baseplate/glenosphere assemblies (Equinoxe, Exactech, Inc) were fixated to 15 lb/ft3 density rigid polyurethane bone substitute blocks. Displacement of the assemblies in the A/P and S/I axes was measured using digital displacement indicators by applying a physiologically relevant 357N shear load parallel to the face of the glenosphere, and a nominal 50N compressive axial load perpendicular to the glenosphere. Westerhoff et al. reported in vivo shoulder loads while ambulating with axillary crutches had a maximum resultant force of 170% times the patient's bodyweight with the arm at 45.25° of abduction1. This was recreated by applying a 1435.4N compressive load (Average bodyweight of 86.1kg*170%) to a humeral liner and reverse shoulder assembly in an Instron testing apparatus at 45.25° of abduction as shown in Figure 1. The glenosphere was rotated about the humeral component through the arc of the axillary crutch swing, from −5° of extension to 30° of flexion as shown in Figure 2 for 183,876 cycles2. The number of cycles was based on number of steps taken in a day from pedometer data reported by Tudor Locke et al. for patients with movement disorders, extrapolated out to a 6 week postoperative recovery period3. A Student's one-tailed, paired t-test was used to identify whether or not significant displacement occurred, where p<0.05 denoted a significant difference. Results. Displacement in the A/P and S/I axes before and after cyclic loading are presented in Table 1. The S/I direction showed no significant difference in displacement (p≤.0801), whereas the A/P direction showed significant increase in displacement (p≤.0340). The average increase in displacement in the A/P and S/I directions was 43.5 and 35.8 microns, respectively. Discussion and Conclusions. This study was designed to represent a worst case scenario, as a patient is unlikely to bear full bodyweight on crutches immediately postoperatively, and is also unlikely to take as many steps as a healthy individual until full recovery occurs. For these reasons, early results indicate statistically significant displacement could occur if a patient bears full bodyweight on axillary crutches immediately postoperatively. This risk could be lowered after the postoperative recovery period in combination with non-full weight bearing devices such as a cane or a walker. To view tables/figures, please contact authors directly