Peroneal nerve dysfunction after total knee arthroplasty: characterization and treatment

Risk Factors for Peripheral Nerve Injury Following Revision Total Knee Arthroplasty in 132,960 Patients

BACKGROUND

Peripheral nerve injury (PNI) following revision total knee arthroplasty (rTKA) is a potentially devastating injury for patients. This study assessed the frequency of and risk factors for postoperative PNI following rTKA.

METHODS

Patients who underwent rTKA from 2003 to 2015 were identified using the National Inpatient Sample. Demographics, medical histories, surgical details, and complications were compared between patients who sustained a PNI and those who did not to identify risk factors for the development of PNI after rTKA.

RESULTS

Overall, 132,960 patients who underwent rTKA were identified, and 737 (0.56%) sustained a postoperative PNI. After adjusting for confounders, patients with a history of a spine condition (adjusted odds ratio [aOR]: 1.7, 95%-confidence interval 1.2 to 2.4, P = .003) and postoperative anemia (aOR: 1.3, 95%-CI: 1.1 to 1.5, P = .004) had higher risk of PNI following rTKA. Intraoperative periprosthetic fracture (aOR: 1.3, 0.78 to 2.2, P = .308), rheumatoid arthritis (aOR: 1.0, 95%-CI: 0.68 to 1.6, P = .865), and history of knee dislocation (aOR: 1.1, 95%-CI: 0.85 to 1.5, P = .412), were not significantly associated with higher risk for PNI.

CONCLUSIONS

This study found a 0.56% incidence of PNI following rTKA, and patients who had preexisting spine conditions or postoperative anemia were at an increased risk for this complication. Orthopedic surgeons may use the results of this study to appropriately counsel patients on the potential for a PNI following rTKA.

Influence and Clinical Significance of Knee Flexion Angle on the Anatomic Course of the Common Peroneal Nerve in the Posterolateral Corner of the Knee Joint

Background

Detailed knowledge of the anatomic course of the common peroneal nerve (CPN) is crucial for the surgical treatment of the posterolateral corner (PLC) of the knee.

Purpose

To investigate the relationship of the CPN to the PLC of the knee at different flexion angles.

Study Design

Descriptive laboratory study.

Methods

Ten healthy volunteers were recruited to undergo magnetic resonance imaging (MRI) of the knee joint at knee flexion angles of 0°, 30°, 60°, 90°, and 120°. MRI scans at 3 levels (joint line, tibial cut, and fibular tip) were evaluated to determine (1) the distance from the CPN to the PLC and (2) the distances between the CPN and the anterior-posterior and medial-lateral tibial axes. A 3-dimensional model of the knee joint created from MRI scans of a single participant was used to simulate the creation of a fibular tunnel for PLC reconstruction and investigate the relationship between the CPN, fibular tunnel, and guide pin.

Results

The CPN moved posteromedially with increased knee flexion angles. As the flexion angle increased, the distances from the CPN to the anterior-posterior axis and the PLC increased significantly, while the distance to the medial-lateral axis decreased significantly at all 3 measurement levels. The distances between the CPN and anterior-posterior and medial-lateral axes were significantly different among the different knee flexion angles at the different measurement levels. There were no significant differences in the mean distance from the CPN to the posterolateral border of the tibial plateau between 0° and 30° of flexion at the fibular tip level (P = .953). There were statistically significant differences in the distance from the CPN to the PLC of the tibial plateau at the different measurement levels. The 3-dimensional model demonstrated that the position of the CPN relative to the guide pin and the bone tunnel undergoes changes during knee flexion.

Conclusion

Changes in the knee flexion angle produced corresponding changes in the course of the CPN on the posterolateral aspect of the knee joint. The CPN moved posteromedially with increased knee flexion angles.

Clinical Relevance

Increasing the knee flexion angle during PLC reconstruction can effectively avoid direct injury of the CPN.

Prophylactic Common Peroneal Nerve Release for Total Arthroplasty of the Valgus Knee: Surgical Technique and Early Outcomes

Background

Common peroneal nerve (CPN) palsy after primary total knee arthroplasty represents a relatively rare but serious complication. Recently, there has been a growing interest in prophylactic CPN decompression in high-risk patients with significant combined valgus and flexion deformity. This study aimed to examine outcomes at our institution in those undergoing prophylactic CPN decompression at the time of total knee arthroplasty.

Methods

A retrospective evaluation of a single-institution experience with selected patients at high risk for CPN palsy who underwent prophylactic nerve decompression through a separate incision at the time total knee arthroplasty was performed between July 1, 2018 and December 31, 2022. Patient demographics as well as perioperative and intraoperative clinical and radiographic measurements were collected and analyzed.

Results

A total of 14 patients (15 knees) met our inclusion criteria. The mean preoperative femorotibial angle was 18.6° of valgus (range 13°-22°). The mean preoperative flexion contracture was 4.3° (range 0°-25°). The patients with flexion contractures preoperatively had a mean combined valgus/flexion contracture deformity of 28.8° (range 23°-38°) . There was preservation of nerve function in all knees. No knees required subsequent operative intervention within 90 days of surgery.

Conclusions

Early experience with prophylactic CPN release in our high-risk population demonstrates preservation of nerve function in all patients and is reasonable to consider in patients with a large preoperative combined valgus/flexion deformity. Further studies with larger sample sizes would be beneficial in verification of the results with this technique, as well as determining an angular deformity threshold for which CPN release should be considered.

Delayed Onset of Peroneal Nerve Palsy After Total Knee Arthroplasty

Peroneal nerve palsy (PNP) and peroneal nerve dysfunction (PND) are rare complications after total knee arthroplasty (TKA). Although PND tends to manifest as transient lateral leg paresthesias that are associated with knee motion, PNP has characteristic motor deficits, including loss of ankle dorsiflexion and eversion strength. Although PND can manifest days, weeks, or months after surgery, delayed cases of PNP have not been well documented. We describe a 72-year-old woman with a delayed case of sudden-onset PNP 10 weeks after TKA. She had no neurologic deficits preoperatively and was recovering uneventfully at 2 and 6 weeks postoperatively. At 10 weeks, she reported insidious onset of drop foot and sensory changes to the lateral leg and dorsum of the foot. Motor deficits included significant loss of ankle dorsiflexion and eversion strength. After a diagnosis of PNP was confirmed with electrodiagnostic studies and lumbar pathology was ruled out with lumbar magnetic resonance imaging, surgical decompression of the peroneal nerve was performed. By 7 weeks after surgical decompression, she had no sensory deficits and nearly full strength in ankle dorsiflexion and eversion. This case shows that PNP can occur several weeks to months outside of the currently documented timeline. Although PNP is an uncommon risk of TKA, it is important to recognize and treat it when it occurs among patients with significant motor and sensory deficits along the distribution of the peroneal nerve postoperatively. [Orthopedics. 2022;45(6):e342-e344.].

Iatrogenic nerve injury and foot drop: Surgical results in 28 patients

Background:

Most peroneal nerve injuries resulting in foot drop are secondary to trauma or iatrogenic. Foot drop can occur due to potential complications from the hip, lumbosacral spine, and knee surgeries, which are critical to diagnose and manage.

Methods:

We reviewed our foot drop patients’ data to determine the incidence and iatrogenic causes of the injury and managed surgically by neurolysis of the peroneal nerve and transfer of functional fascicles of either the superficial peroneal or the tibial nerve to the deep peroneal nerve.

Results:

We found 28 iatrogenic foot drop patients who have had surgery and postoperative follow-up evaluations with us. Before the onset of foot drop, all except one (27 of 28) patient have had surgeries in other clinics before presenting to our institution. Foot drop in one patient was due to infection and hip wound after he was intubated and stayed in ICU for 4 weeks. Thirteen of the 28 patients have had lumbosacral (L3-4, L4-L5, and L5-S1) fusion or laminectomy, eight have had hip surgery, and five have had knee surgery. One patient had a fasciotomy due to compartment syndrome and another patient had two previous surgeries for posterior tibial entrapment and tarsal tunnel syndrome at other institutions. NCS and EMG reports showed that these patients had injuries to the peroneal or tibial nerve after their prior surgeries. One patient had a femoral nerve injury. Preoperatively, 10 patients had severe foot drop with muscle weakness and a functional grade of 0/5; 16 patients had grades ranging from 1 to 2/5; and two patients had 3/5. Overall, 23 of the 28 patients (83%) had improvement in their ankle dorsiflexion with anti-gravity and regained a healthier gait after the decompression, neurolysis, and nerve transfer at our clinic.

Conclusion:

Twenty-three of the 28 (83%) iatrogenic foot drop patients in this report regained a healthier gait with improved ankle dorsiflexion and anti-gravity after the neurolysis, and nerve transfer of the peroneal or tibial nerve and transfer of functional fascicles of either the superficial peroneal or the tibial nerve to the deep peroneal nerve at our clinic.

The Role of Prophylactic Peroneal Nerve Decompression in Patients with Severe Valgus Deformity at the Time of Primary Total Knee Arthroplasty

Background

Common peroneal nerve (PN) palsy after total knee arthroplasty (TKA) is a serious complication. Although many authors suggest delayed or immediate PN decompression after TKA in these patients, little is known about the role of prophylactic peroneal nerve decompression (PPND) at the time of TKA. The aim is to report the results of PPND in high-risk patients at the time of TKA.

Materials and methods

A multi-institutional retrospective study review of nine patients (10 knees) who underwent PPND at the time of TKA was conducted. Patients who had severe valgus deformities (≥15° of femorotibial angle and not fully correctable by examination under anaesthesia) with or without flexion contractures were included. PPND was performed through a separate 3–4-cm incision at the time of TKA. The demographics, preoperative and postoperative anatomical and mechanical alignments, range of motion, operation time, postoperative neurological function and complications were recorded.

Results

All patients had a completely normal motor and sensory neurological function postoperatively and no complications related to PPND were reported. All patients followed the standard physical therapy protocol after TKA without modifications.

The mean preoperative femorotibial angle was 20° (range 15–33°) and the mean postoperative femorotibial angle was 6.3° (range 5–9°) (p = 0.005). The mean preoperative flexion contracture was 9 (range 0–20) and the mean residual contracture was 1.2° (range 2–5°) (p = 0.006).

Conclusion

PPND at the time of TKA is an option to minimise the risk of PN palsy in high-risk patients. This approach can be considered for patients undergoing TKA in selected high-risk patients with a severe valgus deformity.

How to cite this article

Makhdom A, Hamilton AA, Rozbruch SR. The Role of Prophylactic Peroneal Nerve Decompression in Patients with Severe Valgus Deformity at the Time of Primary Total Knee Arthroplasty. Strategies Trauma Limb Reconstr 2022;17(1):38–43.

Complete Foot Drop With Normal Electrodiagnostic Studies: Sunderland "Zero" Ischemic Conduction Block of the Common Peroneal Nerve

ABSTRACT

Common peroneal neuropathy is a peripheral neuropathy of multifactorial etiology often left undiagnosed until foot drop manifests and electrodiagnostic abnormalities are detected. However, reliance on such striking symptoms and electrodiagnostic findings for diagnosis stands in contrast to other commonly treated neuropathies, such as carpal tunnel and cubital tunnel syndrome. Poor recognition of common peroneal neuropathy without foot drop or the presence of foot drop with normal electrodiagnostic studies thus often results in delayed or no surgical treatment. Our cases document 2 patients presenting with complete foot drop who had immediate resolution after decompression. The first patient presented with normal electrodiagnostic studies representing an isolated Sunderland Zero nerve ischemia. The second patient presented with severe electrodiagnostic studies but also had an immediate improvement in their foot drop representing a Sunderland VI mixed nerve injury with a significant contribution from an ongoing Sunderland Zero ischemic conduction block. In support of recent case series, these patients demonstrate that common peroneal neuropathy can present across a broad diagnostic spectrum of sensory and motor symptoms, including with normal electrodiagnostic studies. Four clinical subtypes of common peroneal neuropathy are presented, and surgical decompression may thus be indicated for these patients that lack the more conventional symptoms of common peroneal neuropathy.

Nerve Injuries in Total Knee Arthroplasty

Nerve injury is one of the potential complications of total knee arthroplasty. The extent of the injury includes motor and sensory dysfunction, either temporary or permanent. Although the consequences of nerve injury may be dramatic, the probability of occurrence during the course of primary knee arthroplasty is low, around 0.12% to 0.4%. Local dressing removal and knee flexion are imperative, and the initial investigations include ultrasound or MRI and nerve conduction studies. The extent of recovery depends on the type and severity of the initial nerve palsy; however, most patients are expected to have at least a partial recovery.

An Update on Peroneal Nerve Entrapment and Neuropathy

Peroneal neuropathy is the most common compressive neuropathy of the lower extremity. It should be included in the differential diagnosis for patients presenting with foot drop, the pain of the lower extremity, or numbness of the lower extremity. Symptoms of peroneal neuropathy may occur due to compression of the common peroneal nerve (CPN), superficial peroneal nerve (SPN), or deep peroneal nerve (DPN), each with different clinical presentations. The CPN is most commonly compressed by the bony prominence of the fibula, the SPN most commonly entrapped as it exits the lateral compartment of the leg, and the DPN as it crosses underneath the extensor retinaculum. Accurate and timely diagnosis of any peroneal neuropathy is important to avoid progression of nerve injury and permanent nerve damage. The diagnosis is often made with physical exam findings of decreased strength, altered sensation, and gait abnormalities. Motor nerve conduction studies, electromyography studies, and diagnostic nerve blocks can also assist in diagnosis and prognosis. First-line treatments include removing anything that may be causing external compression, providing stability to unstable joints, and reducing inflammation. Although many peroneal nerve entrapments will resolve with observation and activity modification, surgical treatment is often required when entrapment is refractory to these conservative management strategies. Recently, additional options including microsurgical decompression and percutaneous peripheral nerve stimulation have been reported; however, large studies reporting outcomes are lacking.

Acute Common Peroneal Nerve Decompression After Total Knee Arthroplasty

Common peroneal nerve palsy (CPNP) after total knee arthroplasty has a reported incidence of 0.3% to 4% and can lead to foot drop, equinovarus deformity, and marked disability if not resolved. Patients typically present in the early postoperative period with weakness or inability to dorsiflex the ankle and decreased sensation of the dorsum of the foot. The authors report their experience, technique, and outcomes of acute peroneal decompression within the first 90 days postoperatively for 5 patients with this unique complication. Preoperatively, all patients had valgus deformity with intact dorsiflexion and sensation of the foot. The diagnosis of CPNP was made on postoperative day 0 or 1 in all cases. After diagnosis, patients were offered acute peroneal decompression and returned to the operating room electively. The surgical technique for dissection, release, and decompression of the nerve is described. At an average follow-up of 12 weeks (range, 6-16 weeks), all patients showed return of motor and sensory function, as tested by ankle dorsiflexion and dorsal foot sensation, with average motor strength of 4.6 of 5.3. Acute decompression of acute CPNP after total knee arthroplasty is a prudent treatment option that provides good functional results and rapid recovery. [Orthopedics. 2021;44(4):e556-e562.].

Incidence, Injury Mechanisms, and Recovery of Iatrogenic Nerve Injuries During Hip and Knee Arthroplasty

Iatrogenic nerve injury is a rare but potentially devastating complication in total joint arthroplasty of the hip and the knee. Multiple previous studies have evaluated the incidence, mechanisms of injury, recovery, and potential treatments for this complication. Injury in total hip arthroplasty generally involves direct injury of sensory nerves from the incision, direct or traction injury of during exposure, or limb lengthening. Injury in total knee arthroplasty generally involves direct injury of sensory nerves from incision, injury due to errant placement of retractors, during balancing, or from traction because of deformity correction. Treatment of iatrogenic nerve injuries has ranged from observation, intraoperative prevention by nerve monitoring, limb shortening postoperatively, medications, and decompression. The orthopaedic surgeon should be versed in these etiologies to advise their patients on the incidence of injury, to prevent occurrence by understanding risky intraoperative maneuvers, and to select appropriate interventions when nerve injuries occur.

MR Neurography of Peripheral Nerve Injury in the Presence of Orthopedic Hardware: Technical Considerations

As the frequency of orthopedic procedures performed each year in the United States continues to increase, evaluation of peripheral nerve injury (PNI) in the presence of pre-existing metallic hardware is in higher demand. Advances in metal artifact reduction techniques have substantially improved the capability to reduce the susceptibility effect at MRI, but few reports have documented the use of MR neurography in the evaluation of peripheral nerves in the presence of orthopedic hardware. This report delineates the challenges of MR neurography around metal given the high spatial resolution often required to adequately depict small peripheral nerves. It offers practical tips, including strategies for prescan assessment and protocol optimization, including use of more conventional two-dimensional proton density and T2-weighted fat-suppressed sequences and specialized three-dimensional techniques, such as reversed free-induction steady-state precession and multispectral imaging, which enable vascular suppression and metal artifact reduction, respectively. Finally, this article emphasizes the importance of real-time monitoring by radiologists to optimize the diagnostic yield of MR neurography in the presence of orthopedic hardware. © RSNA, 2021.

Common Peroneal Nerve Injury and Recovery after Total Knee Arthroplasty: A Systematic Review

Background

Common peroneal nerve palsy (CPNP) after total knee arthroplasty (TKA) may impact extremity pain and function. Incidence and rates of recovery of CPNP after TKA vary in the current literature. The purpose of this systematic review was to evaluate the incidence of incomplete and complete CPNP after TKA and rates of incomplete and complete recovery of nerve function in the absence of further surgical treatment.

Methods

PubMed, Embase, and Cochrane Central were searched for studies published in the years 1970-2019. Studies evaluating incidence and recovery rates of CPNP in the absence of further surgical treatment were screened according to inclusion and exclusion criteria. Outcomes of interest included incidence of complete and incomplete CPNP and rates of incomplete and complete nerve recovery.

Results

Eleven studies were included for qualitative analysis. In total, there were 47,585 TKAs performed, with 203 postoperative CPNPs, for a cumulative incidence of 0.4%. One hundred twenty-nine CPNPs were classified as complete or incomplete palsies. At a mean follow-up of 3.6 years (range, 0-11 years), 24 (39%) complete CPNPs had complete recovery, 34 (56%) had incomplete recovery, and 3 were lost to follow-up. In contrast, 45 (66%) with incomplete CPNPs had complete recovery, 18 (27%) had incomplete recovery, and 5 patients were lost to follow-up.

Conclusions

Incidence of CPNP after TKA was 0.4%. Recovery of nerve function after CPNP in the setting of TKA varies by the degree of initial nerve palsy. These data may be used to inform decisions on further interventions and for the purposes of perioperative patient counseling after TKA.

Incidence and Risk Factors for Peripheral Nerve Injury After 383,000 Total Knee Arthroplasties Using a New York State Database (SPARCS)

BACKGROUND

Peripheral nerve injury (PNI) is a devastating complication following total knee arthroplasty (TKA). The purpose of this study is to identify risk factors for PNI after TKA using a New York Statewide Planning and Research Cooperative System.

METHODS

The Statewide Planning and Research Cooperative System database was queried to identify patients who had undergone TKA from 1996 to 2014. Patient demographics, medical history, surgical details, hospital characteristics, and in-hospital complications were recorded. Cases in which a new unilateral PNI was identified were compiled, as were control cases. The characteristics of cases and controls underwent univariate testing and a multivariate logistic regression using Akaike information criterion model selection to identify risk factors for the development of PNI after TKA.

RESULTS

In total, 383,060 cases were identified and 0.12%, or 445/383,060, experienced a new PNI. Pre-existing spinal conditions (odds ratio [OR] 1.98, confidence interval [CI] 1.08-3.30) and valgus deformity (OR 4.19, CI 2.46-6.66) were strongly correlated with the development of PNI postoperatively individually, but together increased risk substantially (OR 17.28, CI 2.83-55.35). Younger age (<50 years), in-hospital complications, female gender, and bilateral surgery were all associated with postoperative PNI, as well.

CONCLUSION

Valgus deformity and previous spine disorder together greatly increased the risk of PNI after TKA. Younger age, female gender, and in-hospital postoperative complications all increased the risk of PNI, as well. This study quantifies the relative risk each of these factors impart in the development of PNI after TKA and can help healthcare providers and systems identify and counsel patients at higher risk of this serious complication.

GR. Assessing the relationship of the peroneal nerve to the posterolateral corner of the knee and influence of race on its dimensions- A MRI based study in Indian population

BACKGROUND

The relationship of Common peroneal nerve (CPN) to the posterolateral corner of the knee joint is important for surgeons who perform total knee arthroplasty to avoid injury to the nerve during surgery. This relationship varies among different races on account of anthropometry. This study aims to evaluate the anatomical location of this nerve in Indian patients using an MRI based reference system.

METHODS

213 knee magnetic resonance images (MRIs) were evaluated in axial plane 8 mm below the joint line for distance of the CPN from the closest posterolateral capsule. The angle of the CPN from the center of the tibial anteroposterior axis and relation of CPN with respect to the popliteus were evaluated. A comparative analysis of these measurements among Caucasian, Chinese and Indian patients was made to evaluate for any differences.

RESULTS

The mean distance between the CPN and the knee capsule was 15.55 mm (range, 7.8-26.2 mm). The mean angle of the CPN from the center of the AP axis was 50.1° (range, 38-63). CPN was found to be in line with the popliteus from center of the knee in 62% cases. There was no significant difference among the different races among the measured parameters (p > 0.005).

CONCLUSION

This study establishes a "danger zone" and a "safe zone" to avoid CPN injury in total knee arthroplasty in Indian patients and identifies anatomic landmarks to localize the nerve before the soft-tissues release in order to avoid direct injury.

Indications for neuromuscular ultrasound: Expert opinion and review of the literature

Over the last two decades, dozens of applications have emerged for ultrasonography in neuromuscular disorders. We wanted to measure its impact on practice in laboratories where the technique is in frequent use. After identifying experts in neuromuscular ultrasound and electrodiagnosis, we assessed their use of ultrasonography for different indications and their expectations for its future evolution. We then identified the earliest papers to provide convincing evidence of the utility of ultrasound for particular indications and analyzed the relationship of their date of publication with expert usage. We found that experts use ultrasonography often for inflammatory, hereditary, traumatic, compressive and neoplastic neuropathies, and somewhat less often for neuronopathies and myopathies. Usage significantly correlated with the timing of key publications in the field. We review these findings and the extensive evidence supporting the value of neuromuscular ultrasound. Advancement of the field of clinical neurophysiology depends on widespread translation of these findings.

Risk factors for acute nerve injury after total knee arthroplasty

INTRODUCTION

In this we study identified potential risk factors for post-total knee arthroplasty (TKA) nerve injury, a catastrophic complication with a reported incidence of 0.3%-1.3%.

METHODS

Patients who developed post-TKA nerve injury from 1998 to 2013 were identified, and each was matched with 2 controls. A multivariable logistic regression model was built to calculate odds ratios (ORs).

RESULTS

Sixty-five nerve injury cases were identified in 39,990 TKAs (0.16%). Females (OR 3.28, P = 0.003) and patients with history of lumbar pathology (OR 6.12, P = 0.026) were associated with increased risk of nerve injury. Tourniquet pressure < 300 mm Hg and longer duration of anesthesia may also be risk factors.

DISCUSSION

Surgical planning for females and patients with lumbar pathology should be modified to mitigate their higher risk of neurologic complications after TKA. Our finding that lower tourniquet pressure was associated with higher risk of nerve injury was unexpected and requires further investigation. Muscle Nerve 57: 946-950, 2018.

Delayed compression of the common peroneal nerve following rotational lateral gastrocnemius flap: case report

The authors present a case of delayed peroneal neuropathy following a lateral gastrocnemius rotational flap reconstruction. The patient presented 1.5 years after surgery with a new partial foot drop, which progressed over 3 years. At operation, a fascial band on the deep side of the gastrocnemius flap was compressing the common peroneal nerve proximal to the fibular head, correlating with preoperative imaging. Release of this fascial band and selective muscle resection led to immediate improvement in symptoms postoperatively.

Nerve Decompression Surgery After Total Hip Arthroplasty: What Are the Outcomes?

BACKGROUND

The purpose of our study was to compare (1) muscle strength; (2) pain; (3) sensation; (4) various outcome measurement scales between post-total hip arthroplasty (THA) patients who had a sciatic nerve injury and did or did not receive decompression surgery for this condition; and (5) to compare these findings with current literature.

METHODS

Nineteen patients who had nerve injury after THA were reviewed. Patients were stratified into those who had a nerve decompression (n = 12), and those who had not (n = 7). Motor strength was evaluated using the Muscle Strength Testing Scale. Pain was evaluated by using the visual analogue scale. Systematic literature search was performed to compare the findings of this study with others currently published.

RESULTS

The decompression group had a significant improvement in motor strength and the visual analog scale scores as compared with nonoperative group. Patients in decompression group had a significant larger increase in the mean Harris hip score and University of California Los Angeles score. There was no significant difference in the increase of Short Form-36 physical and mental scores between the 2 groups. Literature review for nonoperative management yielded 5 studies (93 patients), with 33% improvement. There were 7 studies (81 patients) on nerve decompression surgery, with 75% improvement.

CONCLUSION

This study demonstrates the benefits of nerve decompression surgery in patients who had sciatic nerve injury after THA, as evidenced by results of standardized outcome measurement scales. It is possible to achieve improvements in terms of strength, pain, and clinical outcomes. Comparative studies with larger cohorts are needed to fully assess the best candidates for this procedure.

The Distance of the Common Peroneal Nerve to the Posterolateral Structures of the Knee

BACKGROUND

The common peroneal nerve (CPN) is an important structure of the lower limb and is at risk of injury during total knee arthroplasty. The aim of this study was to use a tibial reference system to determine the position of the CPN relative to the knee center and popliteus.

METHODS

Two hundred consecutive knee magnetic resonance images at the level of a standard tibial arthroplasty cut were evaluated for (1) distance of the CPN from the posterolateral capsule; (2) angle of the CPN from the center of the tibial anteroposterior axis; and (3) location of CPN with respect to the popliteus.

RESULTS

The mean distance between the CPN and the posterolateral joint capsule was 11.9 mm (range, 4.7-22.13 mm), which correlated positively with the medial-lateral axis of the tibia (Pearson correlation, 0.157; P = .026) and negatively with the angle of the nerve from the midline (Pearson correlation, -0.237, P = .001). The mean angle of the nerve from the midline was 42.2° (range, 25.0°-64.0°). In 116 knees (58%), the CPN was in line with the popliteus from the center of the knee, in 69 knees (34.5%) the CPN was lateral to the popliteus, and in 15 knees (7.5%), the CPN was medial to the popliteus. A danger zone was identified as between 29.95° and 54.57° from the anteroposterior axis.

CONCLUSION

The CPN is at risk during total knee arthroplasty. This study describes a method to help predict the location of the CPN intraoperatively and therefore avoid direct injury.

Surgical outcome of foot drop caused by common peroneal nerve injuries; is the glass half full or half empty?

BACKGROUND

Foot drop is a gait abnormality with various etiologies. The Common Peroneal Nerve (CPN) is one of the most frequently injured peripheral nerves. CPN deficit leads to foot drop. Most CPN injuries recover spontaneously; nonetheless, some require nerve surgery. The present study set out to assess the surgical outcomes of foot drop following CPN injuries.

METHOD

Surgical outcomes were reviewed in 36 subjects with foot drop caused by CPN injuries, undergoing surgical nerve exploration. The CPN injuries were confirmed by physical examination, Magnetic Resonance Imaging (MRI) and electrodiagnostic findings.

RESULTS

Subsequent to surgery, a significant improvement was seen in the motor recovery of the subjects. Interestingly, no significant difference in the recovery was found between neurolysis and nerve repair (direct repair and nerve grafting). There was no significant association between the age and the functional recovery. Gender was not associated with the functional recovery. No significant difference was seen in the recovery between thigh-level and knee-level CPN divisions.

CONCLUSIONS

The findings from the present study suggest that nerve surgery can yield beneficial results in the recovery of foot drop following CPN injuries. In addition, the surgical outcome of neurolysis in the treatment of CPN injuries can be similar to that of the nerve repair (direct repair or nerve grafting). This may show the value of nerve repair, which was comparable to neurolysis in the treatment of CPN injuries.

Peroneal Nerve Palsy: Evaluation and Management

Peroneal nerve palsy is the most common entrapment neuropathy of the lower extremity. Numerous etiologies have been identified; however, compression remains the most common cause. Although injury to the nerve may occur anywhere along its course from the sciatic origin to the terminal branches in the foot and ankle, the most common site of compressive pathology is at the level of the fibular head. The most common presentation is acute complete or partial foot drop. Associated numbness in the foot or leg may be present, as well. Neurodiagnostic studies may be helpful for identifying the site of a lesion and determining the appropriate treatment and prognosis. Management varies based on the etiology or site of compression. Many patients benefit from nonsurgical measures, including activity modification, bracing, physical therapy, and medication. Surgical decompression should be considered for refractory cases and those with compressive masses, acute lacerations, or severe conduction changes. Results of surgical decompression are typically favorable. Tendon and nerve transfers can be used in the setting of failed decompression or for patients with a poor prognosis for nerve recovery.

Treatment of peroneal nerve injuries with simultaneous tendon transfer and nerve exploration

Background

Common peroneal nerve palsy leading to foot drop is difficult to manage and has historically been treated with extended bracing with expectant waiting for return of nerve function. Peroneal nerve exploration has traditionally been avoided except in cases of known traumatic or iatrogenic injury, with tendon transfers being performed in a delayed fashion after exhausting conservative treatment. We present a new strategy for management of foot drop with nerve exploration and concomitant tendon transfer.

Method

We retrospectively reviewed a series of 12 patients with peroneal nerve palsies that were treated with tendon transfer from 2005 to 2011. Of these patients, seven were treated with simultaneous peroneal nerve exploration and repair at the time of tendon transfer.

Results

Patients with both nerve repair and tendon transfer had superior functional results with active dorsiflexion in all patients, compared to dorsiflexion in 40% of patients treated with tendon transfers alone. Additionally, 57% of patients treated with nerve repair and tendon transfer were able to achieve enough function to return to running, compared to 20% in patients with tendon transfer alone. No patient had full return of native motor function resulting in excessive dorsiflexion strength.

Conclusion

The results of our limited case series for this rare condition indicate that simultaneous nerve repair and tendon transfer showed no detrimental results and may provide improved function over tendon transfer alone.

Perioperative lower extremity peripheral nerve traction injuries

Peripheral nerve traction injuries may occur after surgical care and can involve any of the lower extremity large peripheral nerves. In this review, the authors discuss injuries after knee or hip surgical intervention. The diagnosis, including electrodiagnostic studies, is time sensitive and also relies on a detailed history and physical examination. Successful prevention and treatment involve familiarity with risk and predisposing factors as well as prophylactic measures.

Surgical decompression improves symptoms of late peroneal nerve dysfunction after TKA

Acute peroneal nerve palsy is a well-known complication of total knee arthroplasty (TKA) that causes a neurological deficit typically seen within hours or days postoperatively. Peroneal nerve dysfunction presents more subtlely than peroneal nerve palsy, with decreased knee range of motion, lateral knee pain, or both following TKA. The diagnosis of peroneal nerve dysfunction may not be suspected for weeks, months, or even years after TKA. Electromyography and nerve conduction studies can support the diagnosis. Historically, peroneal nerve palsy following TKA has been treated nonoperatively but has had an unsatisfactory rate of complete recovery. Recently, a few reports have demonstrated that patients with either peroneal nerve palsy or dysfunction after TKA have had excellent results with surgical decompression of the peroneal nerve.The authors describe a 63-year-old woman who reported transient episodes of lateral knee and leg pain for years after undergoing TKA. She eventually underwent electromyography and nerve conduction studies that indicated a diagnosis of peroneal nerve dysfunction. Approximately 10 years after the TKA, she underwent surgical decompression of the peroneal nerve and has done well since, with significant pain relief and an increased activity level.This case supports the recent literature describing peroneal nerve dysfunction as an uncommon but surgically treatable cause of lateral knee pain following TKA. Increased awareness of the condition and its facile treatment via surgical decompression may result in improved outcomes years after TKA.