The discussion of outpatient unicompartmental knee arthroplasty (UKA) requires proof that it can be done safely and effectively, and also begs the question of whether it can be performed in an ambulatory surgery center (ASC) rather than a general hospital (which raises costs and is typically less efficient). Successful outpatient UKA requires carefully crafted algorithms/protocols, home support, preoperative planning and preparation, expectation management, risk stratification (not everyone is a candidate), perioperative pain management and buy-in from patients, support networks and the health care team. Relatively little data is available on the feasibility, safety and potential cost savings associated with this shift in care. We evaluated the costs and short term outcomes and complications of 150 consecutive UKAs performed in an ASC compared to those done in a general hospital both on an inpatient and outpatient basis. Determination of the setting of the outpatient surgery was made based on geographic preference by the patients; otherwise choice of inpatient or outpatient surgery in the hospital was left to the discretion of the surgeon and was primarily based on the patients' comorbidity profile and circumstances of home help. Total direct facility costs were calculated, including institutional supplies and services, anesthesia services, implants, additional PACU medications and services required, and costs associated with operating room use. Only total cost was evaluated, as it is the most consistent cost variable amongst the two institutions evaluated. The mean total direct cost of UKA in a general community hospital with an overnight stay was 1.24 and 1.65 times greater than the cost of UKA performed at the same hospital or an ASC on an outpatient basis, respectively. The mean total direct cost of outpatient UKA in a general hospital was 1.33 times greater than the mean total cost of UKA performed in an ASC. Semi-autonomous robotic technology has been introduced to optimise accuracy of implant positioning and soft tissue balance in UKA, with the expectation of resultant improvement in durability and implant survivorship. Currently, nearly 20% of UKA's in the U.S. are being performed with robotic assistance. It is anticipated that there will be substantial growth in market penetration over the next decade, projecting that nearly 37% of UKA's and 23% of TKA's will be performed with robotics in 10 years (Medical Device and Diagnostic Industry, March 5, 2015). First generation robotic technology improved substantially implant position compared to conventional methods; however, high capital costs, uncertainty regarding the value of advanced technologies, and the need for preoperative CT scans were barriers to broader adoption. Newer image-free robotic technology offers an alternative method for further optimizing implant positioning and soft tissue balance without the need for preoperative CT scans and with price points that make it suitable for use in an ASC. Currently, as a result of cost and other practical issues, <1% of first generation robotic technologies are being used in ASC's. Alternatively, more than 35% of second generation robotic systems are in use in ASC's for UKA, due to favorable pricing. In conclusion, UKA can be safely performed in the outpatient setting in select patients. Additionally, we demonstrated a substantial cost savings when UKA is performed in an outpatient setting and care is shifted from a general community hospital to an ASC. Finally, robotics can be utilised to optimise accuracy of implant placement and soft tissue balance in UKA, and newer image-free robotic technology is cost effective for outpatient UKA

As with any revision knee arthroplasty, the first rule of revision is to ensure that the reason for failure has been identified, as revision for pain alone is associated with poor results. This is particularly important when considering revision of a UKA, as surgeons may have a lower threshold for revision than following TKA given the perception that the revision is “easy” and that the pain is “probably from the unresurfaced compartments”. In a multi-center study, we found that many patients undergoing revision of a failed UKA do not have an appropriate evaluation for infection. Evaluation should include a screening ESR and CRP and if abnormal, an aspiration of the knee joint for synovial fluid WBC count, differential and culture. To revise a UKA to a TKA, we perform the revision as we would a primary TKA, ignoring the implanted femoral component and using it to assist with reference of femoral component rotation and for the distal femoral cut; the component is not removed until it must for the final preparation. After finishing the femoral component cuts, the tibia is completely exposed prior to carefully removing the tibial component and re-cutting the tibia. In our experience of 45 consecutive both component revisions of UKA to TKA at Rush, 44 used primary implants (98%), including cruciate retaining implants in 36 of these 44 knees (82%; the balance were PS implants) and tibial stems were utilised in 6 of 44 knees (14%). In order to better understand the outcomes of revision of failed UKA we studied 49 patients revised from UKA to TKA and 43 revised from HTO to TKA and matched them to 43 aseptic, both component revision TKA and 97 primary TKA. At a mean of 4.8 years, the KSS and Function Scores in the UKA to TKA, HTO to TKA and primary TKA cohorts were similar. Total operative times were significantly higher in the HTO to TKA and revision TKA groups. Length of hospital stay was shorter in the primary TKA cohort. The rate of complications and reoperations were higher in the HTO to TKA and revision TKA groups compared to the UKA to TKA and primary TKA groups. Based on these results, we believe that revising an HTO and UKA to a TKA both had functional outcomes more similar to a primary than a revision TKA, however, the complication rate of revising an HTO was more similar to a revision than a primary TKA

Introduction. Persistent pain after medial unicompartmental knee arthroplasty (UKA) is a prevailing reason for revision to total knee arthroplasty (TKA). Many of these pathologies can be addressed arthroscopically. The purpose of this study is to examine the outcomes of patients who undergo an arthroscopy for any reason after medial UKA. Methods. A query of our practice registry revealed 58 patients who had undergone medial UKA between October 2003 and June 2015 with subsequent arthroscopy. Mean interval from UKA to arthroscopy was 22 months (range, 1–101 months). Indications for arthroscopy were acute anterior cruciate ligament tear (1), arthrofibrosis (7), synovitis (12), recurrent hemarthrosis (2), lateral compartment degeneration including isolated lateral meniscus tears (11), and loose cement fragments (25). Results. Mean follow-up after arthroscopy was 37 months (range, 1–134 months). Twelve patients have been revised from UKA to TKA. Relative risk of revision after arthroscopy for lateral compartment degeneration was 4.27 (6 of 11; 55%; p=0.002) and for retrieval of loose cement fragments was 0.05 (0 of 25; 0%; p=0.03). Relative risk for revision after arthroscopy for anterior cruciate ligament tear, arthrofibrosis, synovitis, or recurrent hemarthrosis did not meet clinical significance secondary to the low number of patients in these categories. Conclusions. The results of this study suggest that arthroscopic retrieval of cement fragments does not compromise UKA longevity. However, arthroscopy for lateral compartment degradation after UKA predicts a high risk of revision to TKA regardless of its relative radiographic insignificance

A majority of patients present with varus alignment and predominantly medial compartment disease. The secret of success in osteoarthritis (OA) treatment is patient selection and patient specific treatment. Different wear patterns have been described and that knowledge should be utilised in modern knee surgery. In case of isolated anteromedial OA, unicompartmental knee arthroplasty (UKA) should be one of the therapeutic options available to the knee surgeon. The discussion not to offer a UKA to patients is based on the fear of the surgeon not being able to identify the right patient and not being able to perform the surgery accurately. The common modes of failure for UKA, which are dislocation or overcorrection leading to disease progression, can be avoided with a fixed bearing implant. Wear can probably be avoided with newer polyethylenes and avoidance of overstuffing in flexion of the knee. Revision for unexplained pain and unknown causes should disappear once surgeons understand persistent pain after surgery much better than they do today. The choice in favor of UKA is a choice of function over survivorship, a choice for reduced comorbidity and lower mortality. Many of the common problems in TKA are not an issue in UKA. Component overhang, decreased posterior offset, changed joint line height, gap mismatch, flexion gap instability, lift off and paradoxical motion hardly exist in UKA if the replacement is performed according to resurfacing principles with respect for the native knee anatomy. New technologies like navigation, PSI and robotics will help with alignment and component positioning. Surgeon education and training should allow over time UKA to be performed by all of us

Introduction. Over the past several decades, numerous surgical procedures have been perfected in the inpatient hospital setting and then evolved into outpatient procedures. This has been shown to be a safe and economical transition for many orthopedic procedures. A prime example is ACL reconstruction. We report here our early experience with our initial consecutive series of outpatient UKA's done in a free standing ASC (ambulatory surgery center). Materials and Methods. From 8/26/2008 to 5/20/12 there were 60 UKA's performed as outpatient procedures at a free standing ASC. Average patient age was 57.7 years (range of 46–69). Medical comorbidities included 22 patients with HTN and 7 with diabetes. All patients had general anesthesia with periarticular injection of the involved knee (25 cc's of Marcaine with epinephrine 1:100,000) and an intraarticular injection after closure of the capsule with 25 cc of Marcaine with epinephrine mixed with 5 cc of morphine sulfate. Patients without allergy to sulfa were given 200mg of Celebrex bid for three days and hydrocodone/acetaminophin 10/325 1–2 tabs q4 hours prn pain. Patients were discharged home when stable, ambulating with aids as needed, with length of stay ranging from 60–180 minutes (average of 85 minutes). Results. No patients required admission to the hospital for any reason. There was one hemarthrosis in a medial UKA which developed on postoperative day 4. There was uneventful resolution of this event with conservative management and an excellent result was achieved. The vast majority of patients were ambulating well and without walking aids at the 2 week postoperative evaluation. The total number of UKAs performed by the author in the ASC since 8/26/2008 is now 282, still without any complications requiring admission to the hospital. Conclusion. Outpatient UKA performed in an ambulatory surgery center was found to be a safe, efficient, and effective method for the management of unicompartmental osteoarthritis of the knee in this relatively healthy cohort of patients. It is now our routine approach for patients undergoing UKA, with inpatient hospitalization being reserved for those patients who are at higher postoperative risk due to multiple medical comorbidities

Converting UKA to TKA can be difficult, and specialised techniques are needed. Issues include bone loss, joint line approximation, sizing, and rotation. Determining the complexity of conversion pre-operatively helps predict the need for augmentation, grafting, stems, or constraint. In a 2009 study from our center, 50 UKA revised to TKA (1997–2007) were reviewed: 9 implants (18%) were modular fixed-bearing, 4 (8%) were metal-backed nonmodular fixed-bearing, 8 (16%) were resurfacing onlay, 10 (20%) were all-polyethylene step-cut, and 19 (38%) were mobile bearing designs; 5 knees (10%) failed due to infection, 5 (10%) due to wear and/or instability, 10 (20%) for pain or progression of arthritis, 8 (16%) for tibial fracture or severe subsidence, and 22 (44%) due to loosening of either one or both components. Insert thickness was no different between implants (P=0.23) or failure modes (P=0.27). Stemmed component use was most frequent with nonmodular components (50%), all-polyethylene step-cut implants (44%), and modular fixed-bearing implants (33%; P=0.40). Stem use was highest in tibial fracture (86%; P=0.002). Augment use was highest among all-polyethylene step-cut implants (all-polyethylene, 56%; metal-backed, 50%; modular fixed-bearing, 33%; P=0.01). Augmentation use was highest in fracture (86%) and infection (67%), with a significant difference noted between failure modes (P=0.003). Failure of nonmodular all-polyethylene step-cut devices was more complex than resurfacing or mobile bearing. Failure mode was predictive of complexity. Reestablishing the joint line, ligamentous balance, and durable fixation are critical to assuring a primary outcome. In a 2013 multicenter study of 3 institutions including ours, a total of 175 revisions of medial UKA in 168 patients (81 males, 87 females; average age of 66 years) performed from 1995 to 2009 with a minimum of 2-year clinical follow-up were reviewed. The average time from UKA to revision TKA was 71.5 months (range 2 months to 262 months). The four most common reasons for failure of the UKA were femoral or tibial loosening (55%), progressive arthritis of the lateral or patellofemoral joints (34%), polyethylene failure (4%) and infection (3%). Mean follow-up after revision was 75 months. Nine of 175 knees (4.5%) were subsequently revised at an average of 48 months (range 6 months to 123 months). The rate of revision was 1.23 revisions per 100 observed component years. The average Knee Society pain and function score increased to 75 and 66, respectively. In the present series, the re-revision rate after revision TKA from UKA was 4.5% at an average of 75 months or 1.2 revisions per 100 observed component years. Compared to published individual institution and national registry data, re-revision of a failed UKA is equivalent to revision rates of primary TKA and substantially better than re-revision rates of revision TKA. These data should be used to counsel patients undergoing revision UKA to TKA

One of the arguments in favor of unicompartmental knee arthroplasty (UKA) is the possibility of an easier revision. Especially if UKA is considered as an early intervention allowing bridging until total knee arthroplasty (TKA) is necessary at later age. If indeed primary TKA results can be obtained at time of revision, UKA becomes a real indication to postpone TKA until a later age. For obtaining primary TKA results, a primary knee should be indicated for the revision. This is possible if the UKA cuts were conservative and within the resection level of a primary TKA. Furthermore bone loss should be contained and either be resected or easily solved with substituting techniques compatible with a primary TKA. Finally, the primary implant utilised should allow a full interchangeability of the tibial and femoral sizes. This allows a lower tibial cut during the revision, often leading to a smaller size but interchangeability avoids downsizing the femur and creating flexion gap instability. If the UKA to TKA revision asks for stems, bone substitutions, joint line changes and more constraint, the primary result will not be obtained. Therefore it is important to select a bone preserving UKA system that allows for conservative bone cuts and avoids deep keel preparations. UKA to TKA with primary components and without gap mismatches or joint line changes leads to excellent outcome

Introduction. Unicompartmental Knee Arthroplasty (UKA) has been offered as a tissue sparing alternative to total knee arthroplasty (TKA) for treatment of early to mid-stage osteoarthritis (OA). While the spared tissue and retention of cruciate ligaments may result in faster recovery, smaller incision, less bone resection, decreased pain and blood loss and more normal kinematics and function, UKA has shown unpredictable results in practice, which may be due to variations in surgical techniques. 1. Recently a robotic-assisted technique has been introduced as a means to provide more consistent and reproducible surgical results. In this study, the early return to function was measured to determine proposed benefits between UKA and TKA. Methods. Patients requiring either UKA or TKA were prospectively enrolled in this IRB approved study. Each patient received pre-operative education regarding their expected physical therapy (PT) regimen, which was uniform for all patients. PT was determined to be concluded when each patient reached an achievable functional endpoint with each of the following 5 criteria: range of motion from 5 to 115 degrees, recovery of flexion and extension strength to 4/5 of pre-operative strength, gait with minimal limp and without an assistive device for 250 feet and ability to ascend and descend a flight of stairs with step over gait and good control. The number of PT visits to reach each functional goal was recorded. Results. 18 patients (19 knees) were enrolled in the study, with 8 females and 10 males. 13 knees received a TKA and 6 received a UKA. Average age was 65.6 ± 6.4 (range: 54–79) and average body mass index (BMI) was 27.62± 4.9 (range: 20.1–36.6). Age and BMI did not differ between the two groups. Average number of PT visits to reach each functional endpoint is listed in table 1 below. While the UKA group required less visits to reach each criteria, a significant difference (P<0.05) was seen in gait with minimal limp, flexion to 115 degrees, and extension of 5 degrees. Table 1. Number of Physical Therapy visits required to reach Functional Endpoint for TKA and UKA patients. Discussion. Early results show less physical therapy is required for UKA patients than TKA patients to reach the same functional goals. As physical therapy accounts for a significant portion of the episode of care for knee arthroplasty, this quicker recovery may result in a decreased economic burden. More patients and longer follow-up are required to determine full clinical and economic benefit of UKA procedure

In unicompartmental knee arthroplasty (UKA), extension gap commonly decreases after inserting the trial components. As most of UKA technique incorporates the fixture of implants using bone cement, it is likely that the gap decreases further when inserting the actual implants. We performed a new additional procedure that enables a precise adjustment of the extension gap. Thirty-two patients who had undergone UKA (ZIMMER Unicompartmental High-Flex Knee System, Zimmer®, Warsaw) using the spacer block technique at our hospital in 2013 were reviewed. Ten cases had difficulties in achieving full extension after the trial implants were inserted, and hence, a new procedure of longitudinal incision between the medial collateral ligament and the posterior capsule was performed. This additional method created a mean increase of 3mm of the extension gap, and facilitated the knee to extend completely. There were no cases that had an increase in the flexion gap. Previously, a tibial osteotomy was added in such cases, but this had a risk of increasing not just the extension gap but also the flexion gap. This method is a valid technique for precise adjustments, and could also be applied to patients with severe flexion contracture to treat by UKA

Purpose. the purpose of this study was to compare the rollback ratio in the bi-cruciate substituting BCS-TKA and the Oxford UKA. Methods. 20 subjects (28 knees) who were performed the BCS-TKA (Journey II: Smith and Nephew) and 24 subjects (29 knees) who were performed the Oxford UKA, were included in this study. Approximately 6 months after surgery, and when the subjects recovered their range of knee motion, following the Laidlow's method (The knee 2010), lateral radiographic imaging of the knee was performed with active full knee flexion. The most posterior tibiofemoral contact point was measured for evaluation of femoral rollback (Rollback ratio). Flexion angle was also measured using the same radiograph and the correlation of rollback and flexion angle was analyzed. As a control, radiographs of the contralateral knees of who were performed Oxford UKA were evaluated (29 knees). Results. The rollback ratios of the BCS-TKA, Oxford UKA, and the control knees were 37.9±4.9%, 35.7±4.2%, and 35.3±4.8% respectively from the posterior edge of the tibia. No significant difference in rollback ratio was observed. The flexion angles of the BCS-TKA, Oxford UKA, and the control knees were 121.8±8.4°, 125.4±7.5°, and 127±10.3°, respectively. No significant difference in knee flexion angle was observed. Significant correlation between rollback ratio and knee flexion angle was observed (p=0.002: Pearson's correlation coefficient =−0.384). Conclusion. In conclusion, BCS-TKA showed no significant difference of rollback ratio when compared with the control knees and the Oxford UKA knees. There is the possibility that the design of BCS-TKA could reproduce the native ACL and PCL function

Objectives. Proximal tibial fracture is one of the most common postoperative complications of unilateral knee arthroplasty (UKA). The objective of the present study is to investigate the risk factors of these fractures, occurred after UKA in our facility. Method. We performed 314 UKAs between May 2006 and December 2013. All cases were done using Oxford UKA. Proximal tibial fractures were observed in 5 cases. 4 cases were female and 1 case was male, and the age at the operation ranged from 73 to 90. All cases were osteoarthritis. 4 cases were diagnosed as stress fracture with minimum displacement, and 1 case was fracture with displacement. We investigated the risk factors of the tibial fracture among those 5 cases. Low bone mineral density(BMD), the presence of medial tibial cortex pinhole, excessive vertical cut, and adjacence of keel and posterior tibia cortex were estimated as risk factors. Results. The loss in BMD was seen in all cases. Medial tibial cortex pinhole was recognized in 2 cases. Excessive vertical cut was recognized in 3 cases. Adjacence of keel and posterior tibia bone cortex was recognized in 3 cases, and the distance between keel and posterior tibia bone cortex was less than 3mm in all of these 3 cases. 4 cases those diagnosed as stress fractures, healed spontaneously with conservative treatment, but the case with displaced fragment needed ORIF. Discussion. Loss in BMD was seen in all cases as predicted, and this is one of the highest risk factors in UKA patient. Preoperative PTH use is recommended when low BMD was seen. Other risk factors are, medial tibial cortex pinhole, excessive vertical cut, and adjacence of keel and posterior tibial cortex. These risk factors are preventable if some cares are taken during the operation. Medial inclination of the tibial plateau should be checked preoperatively to avoid excessive vertical cut. If the distance between keel and posterior tibial cortex is less than 3mm at the preoperative planning, we should consider converting the implant. Furthermore, it is important to pay attention to intraoperative procedures. We should not use heavy hammer and avoid excessive varus force during cementing. For the prevention of tibial fractures after UKA, both strict preoperative planning and prevention of intraoperative errors are important

Total knee arthroplasty (TKA) provides good results even for severe knee osteoarthritis (OA) patients. However, patients often suffer from post-operative pain and have long rehabilitation periods. In recent years, utilization of unicompartmental knee arthroplasty (UKA) has increased in an effort to decrease pain and shorten recovery compared to TKA. Moreover, the long-term results of the UKA have improved. Many surgeons now wonder whether TKA or UKA is better for patients with isolated medial knee OA. In Japan, the government has public insurance system and patients are able to receive the joint replacement surgery inexpensively. This study was conducted to compare the cost the public insurance and the patients co-payment for TKA and UKA. We investigated a series of thirty TKAs and fifteen UKAs performed in Fussa Hospital (Tokyo, Japan) from July 2012 to April 2013. Data from two TKAs' were excluded since the patients had comorbidities (asthma and severe DM) that extended their hospitalizations. Patients were discharged from the hospital if they were able to go up and down the stairs or were able to conduct routine activities of daily living. Total payments the hospital received averaged $19600 (S.D. $1600) for a TKA and $15200 (S.D. $1300) for a UKA. Patients paied averaged of $690 (S.D. $370) for a TKA and $470 (S.D. $170) for a UKA (Figure 1). The surgical fee was $3769 for both TKA and UKA, and was uniform thoughout Japan. The implant price averaged $6200 (S.D. $300) for TKA and $3900 (S.D. $200) for UKA, where prices were also determined by the government. Hospitalization averaged 28 days (S.D. 7 days) for TKA and 21 days (S.D. 6 days) for UKA. For both TKA and UKA, the total cost and the number of days in hospital were highly correlated (R = 0.92 and R = 0.96, respectively). A linear cost model suggests the TKA cost was $210 times days of hospitalization plus $13100 and the UKA cost was $220 times days of hospitalization plus $10000. Patients' payments were not correlated to the days of hospitalization (R = 0.22 and R = 0.45, respectively). TKA and UKA are performed all over the world now and the number of the surgeries increases each year. Althouth each country has a different insurance system, many countries face an increasing and problematic economic burden for both patients and insurance organization (either public or private company). This study showed UKA is less expensive than TKA by $4400, an advantage that might complement the traditional view that UKA is less invasive and often has fewer complications for treating isolating medical compartment OA. For Japanese system, patients pay relatively little out-of pocket despite long hospitalization, and length of stay has a direct and significant effect on total cost for TKA and UKA

Purpose. There is a large gap between UKA and TKA in terms of tissue preservation including bone stock and knee ligament. We have recently introduced bicompartmental UKA (Bi-UKA) to fill the gap and achieve more “physiological” knee than TKA. In this study, we report the short-term results of Bi-UKA. Subjects and Methods. Thirty knees in twenty-nine osteoarthritis patients who underwent Bi-UKA from December 2010 to December 2013 (6 males and 23 females, average age of 75) were clinically and radiologically evaluated with an average observation period of 19 months. The operative indications were (1)confirmed diagnosis of medial and lateral osteoarthritis or osteonecrosis with preserved status of patellofemoral joint; (2)range of knee flexion greater than 110°; (3)flexion contracture less than 20°; (4)clinically stable knee in the frontal and sagittal plane; (5)correctable knee deformity with fine knee congruency. In all cases, fixed type UKA was implanted through a tibia dependent cut using a spacer block. Zimmer Uni and TRIBRID UKA (Kyocera Medical Corporation) were implanted in 18 and 12 cases, respectively. Results. The mean JOA score improved significantly from 57 points preoperatively to 89 points postoperatively. With regard to ROM, the mean extension significantly improved from −6° to −1° (p<0.001), and the mean flexion was almost unchanged from 134° to 139°. Six knees achieved maximum flexion angles of more than 150°. The mean leg alignment was unchanged from 174.5° to 175.2°, although there were five knees in which alignment was corrected by more than 10° after the surgery. All implant alingnments were reasonably acceptable and particularly, the gaps of setting angle between medial and lateral components were quite small in lateral view radiograph. A only major postoperative complication we have experienced was a periprosthetic tibia fracture, which had been successfully treated with screw fixation. Discussion. Bi-UKA is a bone- and ligament-sparing procedure that may provide better knee function and patient satisfaction than does TKA. Complicated surgical procedure, relationship of placement position between medial and lateral prostheses, ligament balancing, and longer-term results remain subjects to be resolved. However, tibia dependent cut technique using spacer block was quite useful to improve the accuracy of implants positioning during Bi-UKA procedure. Our short-term results of Bi-UKA were well acceptable although there were a few complaints or complications. We would like to confirm the usefulness of this procedure and further establish the best indication by increasing the number of patients in the future

There are some reports that the invasive surgery of knee joint replacement repair static and dynamic balance. We investigated the changes in static and dynamic balance and muscle strength in pre- and postoperative of TKA and UKA for the purpose of assessing time dependent improvement. A total of 168 patients (137 TKA; mean age 75.3, 31 UKA; mean age 78.1) were recruited to the study. These patients underwent static and dynamic balance assessment and muscle strength pre operation and 3, 6, 12 months post operation. The parameters of assessment were one leg standing time (open or close eyes), postural sway test (open or close eyes), 3m timed-up-and-go test, maximum stride and Isokinetic muscle strength. We have evaluated both the absolute value and the index which divided the value of the post-operation with the value of pre-operation. Alignment had improved significantly after surgery in TKA and UKA. Isokinetic muscle strength (Fig. 1), one leg standing time with open eyes, 3m timed-up-and-go test (Fig. 2) and maximum stride showed better improvement than pre operation at 3, 6, and 12 months after surgery in TKA and UKA. On the other hand, one leg standing time with close eyes and postural sway test showed no improvement than pre operation at any time after operation (Fig. 3). Butpostural sway test in UKA showed the improvement trend at 3 months after surgery. In contrast, those test in TKA showed no improvement at 3 months after surgery (Fig. 3). Our result showed the improvement of balance function correlated with muscle recovery and improvement of lower limb alignment than equilibrium function after the artificial knee joint replacement surgery. Because one leg standing time with close eyes and one leg postural sway test represent the equilibrium function than other tests. It is interesting that significant difference in the recovery of postural sway in three months after surgery in UKA compared with TKA

Introduction. Clinical outcomes of UKA procedures are sensitive to malalignment of the components, and thus show significant variability in the literature. A new robotic procedure addresses isolated medial compartment osteoarthritis with the classic indications of UKA. Using precision planning through patient specific 3D modeling and reconstruction, a robotic arm gives the surgeon control of resurfacing the knee joint, allowing for consistent precision according to the previously chosen plan. Through the precise preparation of bone surfaces and inter-component alignment, this procedure is designed to significantly increase accuracy and decrease mal-alignment, thus increasing post-operative physical and function outcomes. This paper evaluates four year clinical outcomes of this novel surgical procedure. Methods. The first seventy-three (42 male, 31 female) patients (average age: 71 ±10yrs) to receive a robotically assisted UKA enrolled in an IRB approved outcomes registry. Eleven patients were four years post operative and sixty-two patients were three years post operative at the time of the study. The average follow ups were 45 months and 35 months, respectively (range: 30 to 47 months). The tibial component for all patients was an all-poly inlay design. Results. At one, two, three and four year follow up, all patients showed significant improvements, compared to pre-operative values, in range of motion (p<0.05), Knee Society Knee (p<0.001) and Function (p<0.001) scores, sf-12 PCS scores (p<0.001). Two patients have been revised, for a four year clinical failure rate of 2.34% at an average follow-up of 37 months. Both revisions were due to loosening of the tibial component and occurred at 23.6 and 17.5 months, respectively, after the index procedure. The first was revised to a TKA. The second patient (age 50, BMI 27.2) was revised to a unicompartmental onlay tibial component at 17.5 months after presenting with weight bearing pain in the medial compartment. Upon explantation of the inlay component, the surgeon observed perfect cement-to-bone integration and noted that the failure was due to debonding of the undersurface of the poly to the cement. Optimal alignment of the femur to the tibia remained intact and the patient showed no signs of progressing OA disease. The bone preserving nature of the original inlay tibial component preparation allowed the surgeon to convert the patient to an onlay component with minimal bone resection instead of conversion to a TKA. A cement channel has been added to the inlay design to improve cement fixation effectiveness. In addition, the undersurface of the tibial component has since been removed and replaced with a dovetail channel to improve lift-off resistance of the tibial inlay. This new design has shown to be 10 times stronger in laboratory push out tests. Conclusions. This initial series of robotically guided UKA implantations provided significant improvement in the post-operative function of patients in every functional measurement with only two revisions to date, likely for improper patient selection. The introduction of new procedures and technologies in medicine is routinely fraught with issues associated with learning curves and unanticipated pitfalls. Because the explicit objectives of this novel technology are to optimize surgical procedures to provide more safe and more reliable outcomes, these favorable results provide the potential for significant improvements in orthopedic surgery

Introduction. The introduction of the Stanmore Implants Savile Row mobile-bearing UKA procedure in July 2011 marked a world first – the use of a patient-specific knee implanted with robotic technology – the Sculptor Robotic Guidance Arm (RGA). This union gives a truly personalised solution by designing an implant for each patient based upon preoperative CT data and using Sculptor RGA to prepare the bone accurately so that the implant is correctly positioned as planned. The purpose of this study is to evaluate the accuracy of Sculptor RGA both in-vitro and in-vivo. We report on the accuracy of our first clinical procedures. Methods. In-vitro:. CTs of plastic-bones were used to create plans for Sculptor RGA, establishing a relationship between the implant position and plastic-bone (planned-transform). Sculptor RGA was then used to prepare bones for 16 UKA implants mimicking the clinical set-up. The implants were placed in the prepared bones without cement. A coordinate-measuring-arm was used to register a)the bone, and b)the implant in relation to the bone (achieved-transform). The difference between planned-and-achieved transforms gives the error in implant position. In-vivo:. Preoperative CTs of 8 OA patients, acquired using the low-dose Imperial Knee CT protocol, were used to plan the position and the shape of the patient-specific implants. Intra-operatively, Sculptor RGA was used to register and prepare the bone and the implants were cemented in place. Post-operative CTs were also acquired. Two techniques were used to measure planned-to-achieved positions of the implants: 1). Preoperative-to-postoperative CT image registration followed by extraction of the achieved implant position and comparison with the plan, 2). Surface-to-surface registration of bone-models segmented from the preoperative and postoperative CTs followed by extraction of the achieved implant position and comparison with the plan. Results. For the in-vitro tests, femoral RMS errors averaged 0.8 mm and 1.6° and tibial RMS errors averaged 1.2 mm and 1.6°. For the clinical cases, femoral RMS errors averaged 1.2 mm and 2.6° and tibial RMS errors averaged 1.3 mm and 2.4°. Discussion. The planned-versus-achieved errors are lower for the in-vitro cases compared to the clinical cases. This is partly due to the increased ease of registration in-vitro and also due to the error introduced during cementing in-vivo, which has been reported to give average errors of 2° in UKA. 1. The clinical results also compare favourably with previously published results for robotic UKA: Conditt et al report 1.4 mm and 2.6° for the femur and 1.2 mm and 2.1° for the tibia. 2. . We have previously reported on the accuracy of the predecessor to Sculptor RGA in a study implanting an off-the-shelf UKA prosthesis with the bones clamped and comparing this to the manual technique. 3. In that study the error in the robotic technique averaged femur: 1.0 mm and 2.6°, tibia: 1.1 mm and 2.5° compared to femur: 2.7 mm and 5.5°, tibia: 2.5 mm and 5.3° in the manual group. Conclusion. This study has shown that the combination of Sculptor RGA and a patient-specific knee results in accurate and reproducible implant placement

Background. Unexplained pain is one of the most common complications after Oxford UKAs. We have retrospectively reviewed the patients who underwent Oxford UKAs and investigated those patients with prolonged pain and found that many of these patients had strong tenderness over the Hunter canal and they were well treated with Hunter canal block or administration of Pregabalin. We have checked the details of these prolonged pain and key to the treatment will be discussed. Methods. Between May 2006 and September 2014 we have performed 316 Oxford UKAs. There were 47 males and 269 females with average age of 70.4 years old (46–90). The patients were followed up for at least 6 months (6 months to 8.0 years, mean follow-up period of 3.1 years). The patients were examined both clinically and radiologically. Result. There were 30 knees (9.5%) that showed prolonged pain continuing more than 3 month after the operation(Fig.1). Of these 30 knees, 17 knees had strong tenderness over the Hunter canal, and many patients had numbness and radiating pain toward medial side of the lower extremities. They were diagnosed as having Hunter canal syndrome clinically. Of these 17 knees 5 were treated successfully with Hunter canal block with Lidocaine. Remaining 12 knees were treated with Pregabalin or with Tramadol. All but 1 knee, pain disappeared within 3 months after starting the treatment as we stated. There were 3 cases that were finally diagnosed as having lumbar canal stenosis and L3 root block was effective. For the 10 knees not diagnosed as having Hunter canal syndrome without any tenderness over the Hunter canal, the pain disappeared spontaneously in 2 knees, and the pain disappeared with administration of Pregabalin or Tramadol in 6 knees. Two patients didn't respond to any treatment, they were referred to psychiatrist and diagnosed as having mental problems. There was no abnormal radiolucency, which suggested loosening of the component. As a result, true unexplained pain that continued more than a year was only 1. Discussion. 17 knees out of 30 unexplained pain knees after Oxford UKAs had strong tenderness over the Hunter canal, and the pain disappeared after the saphenous nerve block or adminestration of Pregabalin except for 1 knee. Patients without the diagnosis of Hunter canal syndrome also responded well to either Pregabalin or Tramadol. The pain continuing for more than 3 months after Oxford UKA is usually self-limited and well treated conservatively. With these results, when you see the prolonged pain after Oxford UKA, we strongly recommend just wait and see by conservative treatment with Pregabalin, Tramadol or saphenous nerve block, and do not revise the implant

Time analysis from video footage gives a simple outcome measure of surgical practice against a measured model of use. The added detail that can be produced, over simply recording the usual surgical process data such as tourniquet times, allows us to identify and time the sequence of surgical procedures as stages, to describe issues, and the identification of idiosyncratic behaviours for review and comparison.

Makoplasty (Mako surgical corp. FL, US) partial knee operation times were compared using this technique with those from the Oxford (Biomet, IN, US) partial knee. Three experienced surgeons were observed over 19 Makoplasty procedures ([Consultant 1] 11, [Consultant 2] 5, [Consultant 3] 3) and 2 experienced surgeons over 11 Oxford partial knee procedures ([Consultant 1] 5, [Consultant 2] 6). Times were refined into separate stages that defined the major operative steps of both the Makoplasty and Oxford processes as used by the surgical team at the Glasgow Royal Infirmary, UK. The videos were reviewed for start and stop times for pre-defined actions that would be expected to be observed during each surgical process and from these stage lengths were calculated. For both the Oxford and Mako system 12 comparable stages were identified for comparison and the timing of the various episodes was tested for statistical significance using a Two-Sample, two tail, t-Test. assuming Equal Variances. [Stages: 1. Setup time, 2. Patient on table, 3. Skin incision, 4. Joint Prep, 5. Robot registration (Not in Oxford), 6. Tibial resection, 7. Femoral resection, 8. Trials, 9. Finishing, 10. Cementing and Washout, 11. Closure and dressing, 12. Off table]

The MAKOplasty procedures were on average longer than Oxfords by 27 minutes. This can largely be accounted for in the additional setup stage 4, where in addition to the usual joint preparation taking a couple of minutes approximately 17 minutes were spent in the MAKO cases undertaking image registration and in stage 5 where nearly five minutes were spent in setting up the robot in the MAKO cases.

In conclusion while operative times fell for the Makoplasties across the learning curve they remained elevated once the plateau was reached. It should be remembered that the surgeons had much less experience with the Makoplasty procedure and were undertaking a randomised clinical trial of outcome and hence were not minded to perform the surgery quickly but to the best of their ability and that this may account for some of the elongated surgical time. Indeed other Makoplasty surgeons report an average surgical time of 30–45 minutes per case and 6 cases per day. What is striking is that the additional steps of registration and robot positioning account for a large proportion of the differences and these are mitigated to some extent by quicker trialling of the implant and finishing of the cuts suggesting more confidence in the suitability of the cut surfaces. There is clearly a need to reduce the registration time to produce more cost effective surgeries.

We hypothesised that the excellent alignments achieved in UKA using a navigation system(NA-MIS UKA) would improve mid-term clinical results versus UKA without a navigation system(MIS-UKA). The clinical results and the component alignment accuracies of NA-MIS UKA and MIS UKA were compared after a minimum follow-up of five years. 56 UKAs in the navigation group and 42 UKAs in conventional group were included. The radiological measurements with regard to the mechanical axis, the inclination of the femoral and tibial components, and radiolucent line or loosening were evaluated and compared between two groups. The clinical evaluations were performed using ROM, WOMAC, HSS and pain score. A significant inter-group difference was found in terms of WOMAC or HSS, pain scores. In the sagittal inclination of the femoral and tibial components, radiolucent line, there were no statistical differences between two groups. However, the outlier numbers at mechanical axis, the mean of coronal inclination of the femoral and tibial component in the two groups was significantly different. The navigation system in UKA can provide improved alignment accuracy of the lower extremity, also there were significant differences in functional outcomes after 5 year-follow-up

INTRODUCTION. The literature suggests a survivorship of unicompartmental knee arthroplasties (UKA) for spontaneous osteonecrosisof the knee range from 93% to 96.7% at 10 to 12 years. However, these data arise from series reporting 23 to 33 patients, jeopardizing meaningful conclusions. OBJECTIVES. Our purpose is to examine a long term survivorship of UKA's in a larger group of patients with SPONK, along with their subjective, symptomatic and functional outcome; to determine the percentage of failures and the reasons for the same in an attempt to identify relevant indications, contraindications, and technical parameters in treating SPONK with a modern implant design. METHODS. We retrospectively evaluated 84 patients with late-stage spontaneous osteonecrosis of the knee who had a medial UKA from 1998 to 2005. All patients had preoperative MRI to confirm the diagnosis, exclude metaphyseal involvemente, and confirm the absence of major degenerative changes in the lateral and patellofermoal compartment. Mean age at surgery was 66 years and mean body mass index was 28.9. A Kaplan-Meier survival analysis was conducted using revision for any reason as the end point. The minimum followup of 63 months (mean, 98 months; range, 63–145 months). RESULTS. The 10-year survivorship was 92%. Ten revisons were performed and the most common reasons for revision were subsidence of the tibial component (four) and aseptic loosening of the tibial component (three). No patient underwent revision for osteoarthritis progression in the lateral or patellofemoral compartment. There was a statistically significant difference between postoperative VAS, KSS, WOMAC, Oxford, Range of Motion and Tibial Slope (overcorrected by 3.7 degrees, p< 0.0023) between the survivors and the failures. CONCLUSION. SPONK may be an optimal indication for UKA provided secondary osteonecrosis of the knee is ruled out; pre-operative MRI is performed to document involvement of other compartments, status of the ligaments and depth of lesion; and there is no over-correction in any plane