The risk of AVN is high in Unstable Slipped Capital Femoral Epiphysis (SCFE) and the optimal surgical treatment remains controversial. Our AVN rates in severe, unstable SCFE remained unchanged following the introduction of the Modified Dunn Procedure (MDP) and as a result, our practice evolved towards performing an Anterior Open Reduction and Decompression (AOR) in an attempt to potentially reduce the “second hit” phenomenon that may contribute. The aim of this study was to determine the early surgical outcomes in Unstable SCFE following AOR compared to the MDP. All moderate to severe, Loder unstable SCFEs between 2008 and 2022 undergoing either an AOR or MDP were included. AVN was defined as a non-viable post-operative SPECT-CT scan. Eighteen patients who underwent AOR and 100 who underwent MPD were included. There was no significant difference in severity (mean PSA 64 vs 66 degrees, p = 0.641), or delay to surgery (p = 0.973) between each group. There was no significant difference in the AVN rate at 27.8% compared to 24% in the AOR and MDP groups respectively (p = 0.732). The mean operative time in the AOR group was 24 minutes less, however this was not statistically significant (p = 0.084). The post-reduction PSA was 26 degrees (range, 13–39) in the AOR group and 9 degrees (range, -7 to 29) in the MDP group (p<0.001). Intra-operative femoral head monitoring had a lower positive predictive value in the AOR group (71% compared to 90%). Preliminary results suggest the AVN rate is not significantly different following AOR. There is less of an associated learning curve with the AOR, but as anticipated, a less anatomical reduction was achieved in this group. We still feel that there is a role for the MDP in unstable slips with a larger remodelling component

Introduction. Correct alignment is important for a successful result after total knee arthroplasty (TKA). During most activities of daily living, the knee is loaded not only in full extension but also in mid-flexion. However, there are few methods to evaluate mid-flexion varus-valgus alignment, despite its clinical significance. Computer navigation systems are useful for intra-operative monitoring of joint positioning and movements. Knee ligaments contribute to induce kinematics of the joint. It is likely that the presence of posterior cruciate ligament has some effects on kinematics throughout flexion. The purpose of this study was to evaluate changes in the varus–valgus alignment of the femoral–tibial mechanical axis in each flexion angle before and after TKA by using a navigation system, and to evaluate varus–valgus kinematic patterns throughout flexion, and compare preoperative and postoperative changes of kinematic patterns in CR-TKA and PS-TKA procedures. Material and Method. Forty knees that underwent TKA with computer navigation system were evaluated (CR-TKA 20; PS-TKA 20). CR and PS TKRs were implanted in alternating sequence. The investigator applied manual mild passive knee flexion, while moving the leg from full extension to flexion and the varus-valgus angle of femoral-tibial mechanical axis was measured automatically by the navigation system at every 10 ° throughout flexion. We classified kinematic patterns in the varus–valgus direction throughout flexion. Results. The mean change in size of the varus–valgus angle associated with full movement was 8.0º preoperatively and 5.3º postoperatively. There was no difference between CR-TKA and PS-TKA. We then evaluated the distribution of changes in size of the varus–valgus angle. Postoperatively, this was limited to 3º or less in many patients, but was also around 6º in many cases, and in some cases it exceeded 10º. For CR-TKA, it was 7º or less in all except one patient, but conversely the change was around 6º in most cases. For PS-TKA, it was limited to 3º or less in most patients, but did exceed 10º in some cases. (Fig.1). We could classify kinematic patterns throughout flexion movement into five broad types. Type A: Varus movement associated with flexion; Type B: Valgus movement associated with flexion; Type C: Same angle position maintained; Type D: Varus movement in the intermediate flexed position; Type E: Valgus movement in the intermediate flexed position. (Fig.2) Kinematic patterns changed before and after TKA in some patients, but in others they remained similar. Among those who underwent CR-TKA, preoperative and postoperative kinematic patterns were similar in 61% of patients, whereas they were different in 80% of those who underwent PS-TKA. Discussion). Our results showed that with respect to postoperative varus–valgus kinematic patterns, the effect of the preoperative varus–valgus kinematic pattern persisted more strongly after CR-TKA compared with PS-TKA. This may have been because in CR-TKA the conserved PCL affects the restriction of varus–valgus movement throughout flexion movements, whereas in PS-TKA it is the post-cam that restricts knee joint movement while also affecting the induction of varus−valgus kinematics with loss of PCL influence

Functional joint stability and accurate component alignment are crucial for a successful clinical outcome after TKA. However, there are few methods to evaluate joint stability during TKA surgery. Activities of daily living often cause mechanical load to the knee joint not only in full extension but also in mid-flexion. Computer navigation systems are useful for intra-operative monitoring of joint positioning and movements. The purpose of this study was to compare the varus-valgus stability between knees treated with cruciate-retaining (CR) and posterior-stabilized (PS) TKA at different angles in the range of motion (ROM) especially in mid-flexion, using the navigation technique. Thirty two knees that underwent TKA with computer navigation technology (precisionN Knee Navigation Software version 4.0, Stryker, Kalamazoo, MI) were evaluated (CR:16; PS:16). The investigator gently applied physiologically allowable maximal manual varus-valgus stress to the knee without angular acceleration, while moving the leg from full extension to flexion, and the mechanical femoral-tibial angle was measured automatically by the navigation system at every 10 degrees throughout the ROM. This measurement cycle was repeated for 3 to 4 times, and maximal varus-valgus laxity was determined as the sum of varus and valgus stress angles for each of the predetermined knee flexion angles. The results of the navigated measurements were used to evaluate varus-valgus instability throughout the ROM and the differences in varus-valgus laxity between pre-TKA (Prior to bone cutting, after navigation registration and suturing of the joint capsule) and post-TKA(After confirming that the TKA components and inserts were firmly placed in an appropriate position, the surgical incision was completely closed). The differences in varus-valgus laxity between the CR and PS groups were compared using the Student's t-test. The knees examined showed the greatest preoperative laxity at 20 to 40 degrees of flexion, with no statistically significant difference between the CR and PS groups (See Figure 1). However, postoperative assessment revealed that PS knees had more varus-valgus laxity than CR knees at all ROM angles examined, and the differences were statistically significant in the flexion range of 10 to 70 degrees (See Figure.2). The differences between preoperative and postoperative joint laxity were analyzed separately for the CR and PS groups. After CR-TKA, joint laxity decreased across all degrees of knee flexion. The differences between preoperative and postoperative joint laxity were statistically significant for the flexion range of 110 to 120 degrees (See Figure.3). On the other hand, knees treated with PS-TKA showed an increase in joint laxity for the flexion range of 10 to 90 degrees. The differences between the preoperative and postoperative values were statistically significant for the flexion range of 10 to 20 degrees in PS-TKA (See Figure.4). We successfully evaluated varus-valgus laxity in this study using a navigation system. The results showed that PS knees had greater varus-valgus laxity than CR knees throughout the ROM, and the differences were statistically significant for the flexion range of 10 to 70 degrees. Altogether, we conclude that PS knees have more mid-flexion laxity than CR knees

Clinical nerve injury has been reported in 0.6–4.8% of shoulder arthroplasties. Classical teaching is that 70–85% of injuries recover. Despite recovery of motor function, overall shoulder function may be negatively affected and residual pain is common. Complex regional pain syndromes may develop and become permanent. Consequently, methods to limit nerve injury have been investigated. In the early 2000's I became concerned about the incidence of nerve injuries in my arthroplasty practice. I became intrigued with the idea of peripheral nerve monitoring as a method to alert the surgeon intra-operatively about impending nerve insults so that evasive measures could be taken to prevent any clinically significant nerve injuries. The results of our first 30 consecutive patients were published in JSES in 2007. Seventeen patients (56.7%) had 30 episodes of nerve dysfunction (i.e. nerve alerts) during surgery. Twenty-three of thirty alerts (76.7%) returned to normal after repositioning the arm to a neutral position. Post-operative EMG was positive in 4 of 7 (57.1%) patients who did not have a return to normal motor latency intra-operatively and in 1 of 10 (10%) patients whose intra-operative nerve function did return to normal. None had clinical nerve injuries. This early experience indicated that nerve injury was potentially more common than previously thought but intra-operative nerve monitoring seemed to have a relatively high false positive rate. Our group subsequently studied 440 shoulder arthroplasty cases. The protocol used to identify a nerve alert was made more restrictive than the first study as an attempt to decrease the false positive rate. In this larger group, nerve alerts occurred in 185 cases (42.0%), and 37 (8.4%) cases did not have signals return to above the alert threshold at closure. There were no permanent post-operative nerve injuries and 5 transient nerve injuries (1.1%). Cases in which MEP amplitudes remained below alert threshold were significantly more likely to have a post-operative nerve injury (p = 0.03). There were no false negatives, (i.e. a post-operative nerve injury occurred while MEPs were normal at closure), making sensitivity 100%. There were 32 false positives, leading to a specificity of 92.6%, a positive predictive value (PPV) of 13.5%, a negative predictive value (NPV) of 100%, and an accuracy (ACC) of 92.3%. In my opinion, the high false positive rate and the low PPV make the technique difficult to justify for routine clinical use